http://www.institut-myologie.org/anglais/ewb_pages/a/actu_news_myologie.phpMyology research highlights.fr-frhttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5728.phpA protein called DUX4, incorrectly expressed in skeletal muscle fibres, is emerging as a major factor in facioscapulohumeral muscular dystrophy (FSHD). In FSHD-affected muscles, full-length DUX4 protein disrupts numerous biochemical processes and appears to inhibit the survival and regeneration of skeletal muscle fibres. Stephen Tapscott, a neurologist and molecular geneticist at the Fred Hutchinson Cancer Research Center in Seattle, was recently interviewed about the DUX4 findings and what they may mean for the FSHD community. He explains why targeting DUX4 and its downstream effects is a promising therapeutic avenue for the treatment of FSHD. In this podcast, Stephen Tapscott describes how a mutation on chromosome 4, in which repeated sequences of DNA are deleted, was identified two decades ago as the root cause of FSHD. Since then, many research groups have tried to identify the mechanism by which this deletion leads to loss of muscle tissue in FSHD. Misregulation of the DUX4 gene and inappropriate expression of the DUX4 protein were proposed early on as possible causes of FSHD, but until recently, the technology wasn't sufficient to demonstrate their involvement. It's now clear that the loss of some of the repeated DNA units on chromosome 4 causes the expression of the DUX4 protein in skeletal muscle tissue, where it's not normally expressed. The presence of DUX4 in skeletal muscle tissue may cause the death of muscle cells via a cell death program known as apoptosis. It also may cause the immune system to attack muscle fibres, and activate proteins that block normal muscle regeneration.Wed, 08 Feb 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5728.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5727.phpThe Muscular Dystrophy Association's latest round of grants allocates more than $12 million to the support of 38 research projects investigating the causes of, and potential treatments for, a number of forms of neuromuscular disease. The new grants, which became effective Feb. 1, support research into more than 15 diseases in MDA's program, including Duchenne muscular dystrophy (DMD), ALS (amyotrophic lateral sclerosis or Lou Gehrig's disease), spinal muscular atrophy (SMA), facioscapulohumeral muscular dystrophy (FSHD), and others. In addition to funding investigations into underlying disease mechanisms, the grants will help guide the development of strategies for diagnosis and treatment. For example, in Pompe disease (acid maltase deficiency), scientists will look for ways to improve the current FDA-approved treatment, enzyme replacement therapy, which sometimes leads to an unwanted immune response. MDA funding also will help refine exciting experimental therapies such as exon skipping in DMD, and gene therapy in DMD and SMA. A number of the new grants are for projects using muscle stem cells, and other strategies to improve muscle regeneration and create new muscle fibres. Six grants are career development grants (DGs) designed to increase the number of scientists committed to working on neuromuscular disease research. Wed, 08 Feb 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5727.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5714.phpDystrophin plays an important role in muscle contraction linking the intracellular cytoskeleton to the extracellular matrix. Mutations of the dystrophin gene leading to a complete loss of the protein cause Duchenne muscular dystrophy (DMD), frequently associated with severe cardiomyopathy. Early clinical trials in DMD using gene transfer to skeletal muscle are underway, but gene transfer to dystrophic cardiac muscle has not been tested in humans yet. The aim of this study was to develop an optimised protocol for cardiac gene therapy in the mouse model of dystrophin-deficiency (mdx) using a cardiac promoter for expression of a microdystrophin (µDys) transgene packaged into an adeno-associated virus (AAV) 9 vector. In this study adult mdx mice were intravenously injected with 1 x 1012 genomic particles of AAV9 vectors containing a cDNA encoding µDys under control of either an ubiquitously active CMV promoter (CMV) or a cardiac specific CMV-enhanced myosin light chain (MLC0.26) promoter. Mice were challenged by voluntary wheel exercise and analysed over 10 months following gene transfer. Both AAV9 vectors led to sustained µDys expression in cardiac muscle, but the MLC promoter conferred about 4-fold higher protein levels. AAV9-CMV-MLC0.26-µDys resulted in a significant protection of cardiac morphology and function as assessed by histopathology, serial echocardiograms and left ventricular catheterization/pressure volume loop measurements. The authors of this study have established an AAV9-mediated gene transfer approach for efficient and specific long-term µDys-expression in the hearts of mdx mice, resulting in a sustained therapeutic effect. Thus, this approach might be a basis for further translation into a treatment strategy for DMD-associated cardiomyopathy.Mon, 30 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5714.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5713.phpIncreased utrophin expression is known to reduce pathology in dystrophin-deficient skeletal muscles. Transgenic over-expression of PGC-1á has been shown to increase levels of utrophin mRNA and improve the histology of mdx muscles. Other reports have shown that PGC-1á signaling can lead to increased oxidative capacity and a fast to slow fiber type shift. Given that it has been shown that slow fibers produce and maintain more utrophin than fast skeletal muscle fibers, the authors hypothesized that over-expression of PGC-1á in post-natal mdx mice would increase utrophin levels via a fiber type shift, resulting in more slow, oxidative fibers that are also more resistant to contraction-induced damage. To test this hypothesis, neonatal mdx mice were injected with recombinant adeno-associated virus (AAV) driving expression of PGC-1á. PGC-1á over-expression resulted in increased utrophin and type I myosin heavy chain expression as well as elevated mitochondrial protein expression. Muscles were shown to be more resistant to contraction-induced damage and more fatigue resistant. Sirt-1 was increased while p38 activation and NRF-1 were reduced in PGC-1á over-expressing muscle when compared to control. Whether the use of a pharmacological PGC-1á pathway activator, resveratrol, could drive the same physiological changes was also evaluated. Resveratrol administration (100 mg/kg/day) resulted in improved fatigue resistance, but did not achieve significant increases in utrophin expression. These data suggest that the PGC-1á pathway is a potential target for therapeutic intervention in dystrophic skeletal muscle.Mon, 30 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5713.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5712.phpγ-Sarcoglycanopathy or limb girdle muscular dystrophy type 2C is an untreatable disease caused by autosomal recessively inherited mutations of the γ-sarcoglycan gene. Nine non-ambulatory patients (two males, seven females, mean age 27 years; range 16-38 years) with del525T homozygous mutation of the γ-sarcoglycan gene and no γ-sarcoglycan immunostaining on muscle biopsy were divided into three equal groups to receive three escalating doses of an adeno-associated virus serotype 1 vector expressing the human γ-sarcoglycan gene under the control of the desmin promoter, by local injection into the extensor carpi radialis muscle. The first group received a single injection of 3 × 10(9) viral genomes in 100 µl, the second group received a single injection of 1.5 × 10(10) viral genomes in 100 µl, and the third group received three simultaneous 100-µl injections at the same site, delivering a total dose of 4.5 × 10(10) viral genomes. No serious adverse effects occurred during 6 months of follow-up. All nine patients became adeno-associated virus serotype 1 seropositive and one developed a cytotoxic response to the adeno-associated virus serotype 1 capsid. Thirty days later, immunohistochemical analysis of injected-muscle biopsy specimens showed γ-sarcoglycan expression in all three patients who received the highest dose (4.7-10.5% positively stained fibres), while real-time polymerase chain reaction detected γ-sarcoglycan messenger RNA. In one patient, γ-sarcoglycan protein was detected by western blot. For two other patients who received the low and intermediate doses, discrete levels of γ-sarcoglycan expression (Mon, 30 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5712.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5711.phpLimb girdle muscular dystrophy 1D/1E (OMIM nomenclature LGMD1D, Human Gene Nomenclature Committee LGMD1E), a skeletal and cardiac myopathy, has previously been linked to chromosome 6q23. Herein the authors used laser capture microdissection to isolate cytoplasmic inclusions from skeletal muscle from a patient with LGMD1D/1E, performed mass spectrometry-based proteomics on these minute inclusions, and identified through bioinformatics desmin as their major constituent. Sequencing in this patient and family members identified the genetic basis of the previously reported 6q23 linked LGMD1D/1E to be due to an intron splice donor site mutation (IVS3+3A>G) of the desmin gene located on chromosome 2q35.Mon, 30 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5711.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5710.phpThis study explored the possibility of copy number mutations in patients with Charcot-Marie-Tooth disease (CMT) whose responsible genes remain undefined, on the basis of the hypothesis that copy number mutations of the genes encoding myelin compact proteins are responsible for myelin disorders in humans. A family with 6 affected members in 3 consecutive generations, presenting with motor and sensory demyelinating polyneuropathy, was investigated. Characteristic clinical features in this pedigree include Adie pupils and substantial intrafamilial variability in the age at onset, electrophysiological findings, and clinical severity. Nucleotide sequence analyses of PMP22, MPZ, or GJB1 and gene dosage study of PMP22 did not reveal causative mutations. Hence, the authors applied a custom-designed array for comparative genomic hybridization (CGH) analysis to conduct a comprehensive screening of copy number mutations involving any of the known causative genes for CMT other than PMP22. The array CGH analyses revealed increased gene dosage involving the whole MPZ, and the flanking genes of SDHC and C1orf192. The gene dosage is estimated to be 5 copies. This mutation showed complete cosegregation with the disease phenotype in this pedigree. The increased gene dosage of MPZ and increased expression level of MPZ mRNA emphasise the important role of the dosage of the MPZ protein in the functional integrity of peripheral nerve myelin in humans, and provide a new insight into the pathogenic mechanisms underlying CMT.Mon, 30 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5710.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5705.phpResearchers have now identified the genes and proteins, which damage muscle cells, as well as the mechanisms that can cause a common form of muscular dystrophy. The discovery made by an international team of researchers led by a scientist at Fred Hutchinson Cancer Research Center could lead to a biomarker-based test for diagnosing facioscapulohumeral muscular dystrophy (FSHD), and the findings have implications for developing future treatments as well as for cancer immunotherapies in general. The work established a viable roadmap for how the expression of the DUX4 gene can cause FSHD. Whether this is the sole cause of FSHD is not known; however, the latest findings are strong evidence of the genetic link. Dr. Tapscott and colleagues sought answers to the questions about what the DUX4 protein does both normally in the body and in the FSHD disease process. In the latest study, they identified that the DUX4 protein regulates many genes that are normally expressed in the male germ line but are abnormally expressed in FSHD muscle. This study is a significant step forward by solidifying that the DUX4 transcription factor causes this disease, while offering a number of viable mechanisms for why the muscle is damaged. Now that scientists know that targets for DUX4 are expressed in skeletal muscle, an antibody- or RNA-based test could be developed to diagnose FSHD by examining muscle tissue from a biopsy. Such biomarker-based tests also could be used to determine how well new treatments are working to suppress FSHD.Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5705.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5704.phpThe coexistence of systemic lupus erythematosus (SLE) and myasthenia gravis (MG) is rarely reported, and most of the published studies are case reports. Hydroxychloroquine, an antimalarial agent, is an essential treatment in patients with SLE but special caution is recommended when used in MG patients. Herein, the authors retrospectively analyzed the clinical features, laboratory findings, and outcome of 17 patients with both diseases with a special focus regarding hydroxychloroquine use and with a review of the literature. All patients were women. The mean age at MG onset and SLE diagnosis was 34.5 [14-64] and 37.8 [18-72] years, respectively. The presenting symptoms of MG were limb weakness (94%), ocular (88%) and bulbar involvement (53%). Autoantibodies against the acetylcholine receptor were positive in 94% of cases. The main manifestations of SLE included arthritis (88%), cytopenias (53%) and skin rash (41%). Treatment of SLE required hydroxychloroquine (94%), steroids (47%) and immunosuppressive drugs (18%). Among eight patients (47%) who developed MG after initiation of hydroxychloroquine, the question of induction of MG by hydroxychloroquine was raised in one patient. On the other hand, an exacerbation of myasthenic symptoms was only seen in one of the eight patients who received hydroxychloroquine after the diagnosis of MG. Including the cases in this study, a total of 70 patients with SLE and MG were reviewed. Compared with a large series of 1,000 unselected SLE patients, those with associated MG were older, had lower incidence of cutaneous, renal, and neurological manifestations, and higher frequency of anticardiolipin antibodies and lupus anticoagulant. In conclusion, the clinical pattern of patients with SLE and MG seems to be characterized by a less severe course of SLE and higher frequency of antiphospholipid antibodies. Hydroxychloroquine treatment appears to be safe in this setting.Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5704.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5703.phpThe precise function of an enzyme critical for normal muscle structure which is also involved in several muscular dystrophies has been identified by researchers at the University of Iowa. The findings could be used to develop rapid, large-scale testing of potential muscular dystrophy therapies. The enzyme, called LARGE, adds a critical sugar chain onto dystroglycan, thus reinforcing cell membranes in many tissues including muscle and brain. Dystroglycan does not function properly without this sugar link, resulting in muscular dystrophies and brain abnormalities. The new study shows that the enzyme activity of LARGE transfers the sugars xylose and glucuronic acid. Using nuclear magnetic resonance analysis (NMR), the team was also able to determine the precise structure of the sugar chain produced by LARGE, which has not previously been observed. The study confirmed that this unique sugar chain is responsible for dystroglycan's ability to link proteins such as laminin in muscle and neurexin in brain. In addition to LARGE, several other enzymes are involved in building the important dystroglycan sugar chain, and mutations in all these enzymes cause congenital muscular dystrophies collectively known as secondary dystroglycanopathies. These disorders include Fukuyama Congenital Muscular Dystrophy, Walker-Warburg Syndrome, Muscle-Eye-Brain disease, Congenital Muscular Dystrophy 1C and 1D, and limb-girdle muscular dystrophy 2I. However, in all cases, the part of the sugar chain that is critical for dystroglycan function is the part that is added by LARGE. By understanding the function of the LARGE enzyme, the researchers have now been able to develop an enzyme assay, which could be used in a large-scale high-throughput screen for drugs that increase (or decrease) LARGE activity. Using the assay to identify compounds that boost LARGE activity might lead to potential treatments for the secondary dystroglycanopathies. The assay could also be used to look at variations in LARGE activity in patients' cells. This may help identify patients who are affected by these LARGE-related muscular dystrophies.Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5703.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5702.phpLittle is known about the vascular function and expression of endothelial and neuronal nitric oxide synthases (eNOS and nNOS) in Duchenne muscular dystrophy (DMD). Bradykinin is involved in the regulation of eNOS expression induced by angiotensin-converting enzyme inhibitors. We characterized the vascular function and eNOS and nNOS expression in a canine model of DMD and evaluated the effects of chronic bradykinin treatment. Vascular function was examined in conscious golden retriever muscular dystrophy (GRMD) dogs with left ventricular dysfunction (measured by echocardiography) and in isolated coronary arteries. eNOS and nNOS proteins in carotid arteries were measured by western blot and cyclic guanosine monophosphate (cGMP) content was analyzed by radioimmunoassay. Compared with controls, GRMD dogs had an impaired vasodilator response to acetylcholine. In isolated coronary artery, acetylcholine-elicited relaxation was nearly absent in placebo-treated GRMD dogs. This was explained by reduced nNOS and eNOS proteins and cGMP content in arterial tissues. Chronic bradykinin infusion (1 ěg/min, 4 weeks) restored in vivo and in vitro vascular response to acetylcholine to the level of control dogs. This effect was NO-mediated through upregulation of eNOS and nNOS expression. In conclusion, this study is the first to demonstrate that DMD is associated with NO-mediated vascular endothelial dysfunction linked to an altered expression of eNOS and nNOS, which can be overcome by bradykinin.Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5702.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5701.phpCharcot-Marie-Tooth neuropathy has been reported to be associated with renal diseases, mostly focal segmental glomerulosclerosis (FSGS). However, the common mechanisms underlying the neuropathy and FSGS remain unknown. Mutations in INF2 were recently identified in patients with autosomal dominant FSGS. INF2 encodes a formin protein that interacts with the Rho-GTPase CDC42 and myelin and lymphocyte protein (MAL) that are implicated in essential steps of myelination and myelin maintenance. The authors of this study therefore hypothesized that INF2 may be responsible for cases of Charcot-Marie-Tooth neuropathy associated with FSGS. They performed direct genotyping of INF2 in 16 index patients with Charcot-Marie-Tooth neuropathy and FSGS who did not have a mutation in PMP22 or MPZ, encoding peripheral myelin protein 22 and myelin protein zero, respectively. Histologic and functional studies were also conducted. Nine new heterozygous mutations in 12 of the 16 index patients (75%) were identified, all located in exons 2 and 3, encoding the diaphanous-inhibitory domain of INF2. Patients presented with an intermediate form of Charcot-Marie-Tooth neuropathy as well as a glomerulopathy with FSGS on kidney biopsy. Immunohistochemical analysis revealed strong INF2 expression in Schwann-cell cytoplasm and podocytes. Moreover, it was demonstrated that INF2 colocalizes and interacts with MAL in Schwann cells. The INF2 mutants perturbed the INF2-MAL-CDC42 pathway, resulting in cytoskeleton disorganization, enhanced INF2 binding to CDC42 and mislocalization of INF2, MAL, and CDC42. INF2 mutations appear to cause many cases of FSGS-associated Charcot-Marie-Tooth neuropathy, showing that INF2 is involved in a disease affecting both the kidney glomerulus and the peripheral nervous system. These findings provide new insights into the pathophysiological mechanisms linking formin proteins to podocyte and Schwann-cell function. (Funded by the Agence Nationale de la Recherche and others.).Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5701.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5700.phpDuchenne muscular dystrophy is caused by mutations in the DMD gene that disrupt the open reading frame and prevent the full translation of its protein product, dystrophin. Restoration of the open reading frame and dystrophin production can be achieved by exon skipping using antisense oligonucleotides targeted to splicing elements. This approach aims to transform the Duchenne muscular dystrophy phenotype to that of the milder disorder, Becker muscular dystrophy, typically caused by in-frame dystrophin deletions that allow the production of an internally deleted but partially functional dystrophin. There is ongoing debate regarding the functional properties of the different internally deleted dystrophins produced by exon skipping for different mutations; more insight would be valuable to improve and better predict the outcome of exon skipping clinical trials. To this end, this study describes the characterisation of the clinical phenotype of 17 patients with Becker muscular dystrophy harbouring in-frame deletions relevant to on-going or planned exon skipping clinical trials for Duchenne muscular dystrophy and correlation to the levels of dystrophin, and dystrophin-associated protein expression. The cohort of 17 patients, selected exclusively on the basis of their genotype, included 4 asymptomatic, 12 mild and 1 severe patient. All patients had dystrophin levels of >40% of control and significantly higher dystrophin (P=0.013), â-dystroglycan (P = 0.025) and neuronal nitric oxide synthase (P = 0.034) expression was observed in asymptomatic individuals versus symptomatic patients with Becker muscular dystrophy. Furthermore, grouping the patients by deletion, patients with Becker muscular dystrophy with deletions with an end-point of exon 51 (the skipping of which could rescue the largest group of Duchenne muscular dystrophy deletions) showed significantly higher dystrophin levels (P = 0.034) than those with deletions ending with exon 53. This is the first quantitative study on both dystrophin and dystrophin-associated protein expression in patients with Becker muscular dystrophy with deletions relevant for on-going exon skipping trials in Duchenne muscular dystrophy. Taken together, these results indicate that all varieties of internally deleted dystrophin assessed in this study have the functional capability to provide a substantial clinical benefit to patients with Duchenne muscular dystrophy.Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5700.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5699.phpSpinal Muscular Atrophy (SMA) is an autosomal recessive disorder characterized by á-motor neuron loss in the spinal cord anterior horn. SMA results from deletion or mutation of the Survival Motor Neuron 1 gene (SMN1) and retention of SMN2. A single nucleotide difference between SMN1 and SMN2 results in exclusion of exon 7 from the majority of SMN2 transcripts, leading to decreased SMN protein levels and development of SMA. A series of splice enhancers and silencers regulate incorporation of SMN2 exon 7; these splice motifs can be blocked with antisense oligomers (ASOs) to alter SMN2 transcript splicing. In this study the authors have evaluated a morpholino oligomer against ISS-N1 (HSMN2Ex7D(-10,-29)), and delivered this morpholino (MO) to postnatal day 0 (P0) SMA pups (Smn -/-, SMN2+/+, SMN7 +/+) by intracerebroventricular (ICV) injection. Survival was increased markedly from 15 days to over 100 days. Delayed CNS MO injection has moderate efficacy, and delayed peripheral injection has mild survival advantage, suggesting that early CNS ASO administration is essential for SMA therapy consideration. ICV treatment increased full-length SMN2 transcript as well as SMN protein in neural tissue, but only minimally in peripheral tissue. Interval analysis shows a decrease in alternative splice modification over time. It is suggested that CNS increases of SMN will have a major impact on SMA, and an early increase of SMN level results in correction of motor phenotypes. Last, the early introduction by intrathecal delivery of morpholino oligomers is a potential treatment for SMA patients.Sun, 15 Jan 2012 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5699.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5695.phpResponsive outcome measures are needed to follow the disease status of Duchenne muscular dystrophy (DMD) patients, as new therapeutic approaches become available for affected boys. Quantitative muscle ultrasound (QMUS) is potentially an attractive follow up tool for DMD because it reflects the severity of the dystrophic process without the need for invasive procedures, by quantifying echo intensity (i.e. mean grey level of muscle images) and muscle thickness. Herein, the authors performed a longitudinal follow-up of lower and upper extremity QMUS in 18 DMD patients and compared this with physical functioning in 11 of these patients. QMUS could be performed in every patient, and no patient was subjected to more than a total of 20min of ultrasound scanning time for this study. As expected, they found a significant increase of echo intensity with age, reflecting increasing dystrophic muscle changes. This increase was related to ambulatory status, functional grading, muscle strength and motor ability. This study establishes QMUS as a practical and child-friendly tool for the longitudinal follow up of DMD patients.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5695.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5694.phpThe aim of this study was to estimate the prevalence and nature of sleep breathing disorders in Myotonic dystrophy type 1 (DM1). The authors wanted to determine whether there is a relationship between sleep breathing disorders and clinical parameters such as pulmonary function, degree of neuromuscular impairment, daytime sleepiness, and fatigue. This will help assess the prevalence of DM1 patients requiring nocturnal ventilatory treatments. A random sample of 40 unrelated patients was studied and it was found that 22/40 patients had obstructive sleep apnoea. Of these 22 patients, five also showed periodic breathing and four showed sleep hypoventilation. Nine patients were put on nocturnal ventilation following clinical and instrumental evaluations. This study reveals that obstructive sleep apnoea is very common in these patients, but cannot be predicted on the basis of clinical-neurological features and diurnal functional respiratory tests. These data emphasize that a periodical evaluation by polysomnography should be mandatory to ascertain, and treat if necessary, the presence of obstructive sleep apnoea, periodic breathing or nocturnal hypoventilation.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5694.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5693.phpMyotonic dystrophy types 1 and 2 are progressive multisystemic disorders with potential brain involvement. Twenty-two myotonic dystrophy type 1 and 22 myotonic dystrophy type 2 clinically and neuropsychologically well-characterized patients and a corresponding healthy control group were compared using structural brain magnetic resonance imaging at 3 T (T(1)/T(2)/diffusion-weighted). Voxel-based morphometry and diffusion tensor imaging with tract-based spatial statistics were applied for voxel-wise analysis of cerebral grey and white matter affection (P(corrected) Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5693.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5692.phpMcArdle disease is a rare metabolic myopathy caused by a complete absence of the enzyme muscle glycogen phosphorylase. Affected people experience symptoms of fatigue and cramping within minutes of exercise and are at risk for acute muscle injury (rhabdomyolysis) and acute renal failure. If the first few minutes of exercise are paced, a 'second wind' will occur enabling exercise to continue. This is due to mobilisation and utilisation of alternative fuel substrates. Aerobic training appears to improve work capacity by increasing cardiovascular fitness. The objectives of this study were to assess the effects of aerobic training in people with McArdle disease. The Cochrane Neuromuscular Disease Group Specialized Register (11 January 2011), CENTRAL (2010, Issue 4), MEDLINE (January 1966 to January 2011) and EMBASE (January 1980 to January 2011) were searched. All randomised and quasi-randomised controlled studies of aerobic exercise training in people of all ages with McArdle disease were selected. Two authors identified possible studies for inclusion and assessed their methodological quality. A meta-analysis would have been undertaken if more than one study of sufficient methodological quality had been identified. There were no randomised or quasi-randomised controlled trials of aerobic training in people with McArdle disease. However, three open studies using small numbers of participants provided some evidence that aerobic training improves fitness without adverse events in people with McArdle disease. Evidence from non-randomised studies using small numbers of patients suggest that it would be safe and worthwhile for larger controlled trials of aerobic training to be undertaken in people with McArdle disease. Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5692.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5691.phpFriedreich's Ataxia (FA) is a debilitating neurological disorder that causes loss of balance and coordination (ataxia), difficulty with speech and swallowing, muscle weakness, skeletal abnormalities and cardiac abnormalities. The underlying cause of FA is a deficiency of the frataxin protein, resulting in diminished energy production in cells — including those of the nervous system and heart. It is thought that increasing frataxin levels or finding ways to replicate the functions normally performed by the missing protein may potentially be therapeutic strategies in FA. A research team led by Dr. Mark Payne has demonstrated that a cell-penetrating molecule called TAT (for transactivator of transcription) transported human frataxin protein to cells where it normalised growth, improved heart structure and function, and increased survival rate and life span in a mouse model of severe FA. The team also showed that the TAT delivery method worked in cultured FA-affected human fibroblasts. In these experiments, targeted delivery of frataxin protein to mitochondria caused a reduction in toxicity resulting from oxidative stress. The TAT molecule is able to penetrate cellular membranes, thereby gaining entry to cells. Once inside, the molecule is also able to pass through intracellular membranes such as those encapsulating the mitochondria. This cell-penetrating ability allows TAT molecules to deliver small molecules, DNA fragments or, in this case, frataxin protein. These data support the continued study of the TAT-Frataxin fusion protein, or TAT-FXN as a protein replacement therapy in FA.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5691.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5690.phpThis study aimed to determine whether patients with myasthenia gravis (MG) have serum antibodies to lipoprotein-related protein 4 (LRP4), a newly identified receptor for agrin that is essential for neuromuscular junction formation, and to establish whether such antibodies contribute to MG pathogenesis. Serum samples from patients with MG with known status of serum antibodies to the acetylcholine receptor (AChR) and muscle-specific kinase (MuSK) and serum samples from control subjects (healthy individuals and individuals with other diseases) were tested for antibodies to LRP4. Serum samples with such antibodies were tested to determine whether they had the ability to inhibit 2 different functions of LRP4 at the neuromuscular junction. Serum samples were collected at the Hellenic Pasteur Institute and Wayne State University. Samples were tested for LRP4 autoantibodies at Georgia Health Sciences University. Other immunoreactivities of the samples were tested at the Hellenic Pasteur Institute, Athens, Greece, or processed through University Laboratories of the Detroit Medical Center, Michigan. The study included 217 patients with MG, 76 patients with other neurologic or psychiatric diseases, and 45 healthy control subjects. Anti-LRP4 antibodies were detected in 11 of 120 patients with MG without detectable anti-AChR or anti-MuSK antibodies (double seronegative) and in 1 of 36 patients without anti-AChR antibodies but with anti-MuSK antibodies, but they were not detected in any of the 61 patients with anti-AChR antibodies. No healthy control subjects and only 2 of the 76 control patients with neurologic disease had anti-LRP4 antibodies. Serum samples from patients with MG with anti-LRP4 antibodies were able to inhibit the LRP4-agrin interaction and/or alter AChR clustering in muscle cells. Anti-LRP4 antibodies were detected in the serum of approximately 9.2% of patients with double-seronegative MG. This frequency is intermediate compared with 2 recent studies showing anti-LRP4 antibodies in 2% and 50% of patients with double-seronegative MG from different geographic locations. Together, these observations indicate that LRP4 is another autoantigen in patients with MG, and anti-LRP4 autoantibodies may be pathogenic through different immunopathogenic processes.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5690.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5689.phpAlthough restoration of dystrophin expression via exon skipping in both cardiac and skeletal muscle has been successfully demonstrated in the mdx mouse, restoration of cardiac dystrophin expression in large animal models of Duchenne muscular dystrophy (DMD) has proven to be a challenge. In large animals, investigators have focused on using intravenous injection of antisense oligonucleotides (AO) to mediate exon skipping. In this study, Dr Bish and colleagues sought to optimize restoration of cardiac dystrophin expression in the golden retriever muscular dystrophy (GRMD) model using percutaneous transendocardial delivery of recombinant AAV6 (rAAV6) to deliver a modified U7 small nuclear RNA (snRNA) carrying antisense sequence to target the exon splicing enhancers of exons 6 and 8 and correct the disrupted reading frame. The reults demonstrate restoration of cardiac dystrophin expression at 13 months confirmed by reverse transcription-PCR (RT-PCR) and immunoblot as well as membrane localization by immunohistochemistry. This was accompanied by improved cardiac function as assessed by cardiac magnetic resonance imaging (MRI). Percutaneous transendocardial delivery of rAAV6 expressing a modified U7 exon skipping construct is a safe, effective method for restoration of dystrophin expression and improvement of cardiac function in the GRMD canine and may be easily translatable to human DMD patients.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5689.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5688.phpCongenital myasthenic syndromes (CMS) are clinically and genetically heterogeneous inherited disorders characterized by impaired neuromuscular transmission. Mutations in the acetylcholinesterase (AChE) collagen-like tail subunit gene (COlQ) cause recessive forms of synaptic CMS with end plate AChE deficiency. This study presents data on 15 COLQ -mutant CMS carrying 16 different mutations (9 novel ones identified) followed-up for an average period of 10years. The mean age at the first examination was 19 years old (range from 3 to 48).  Relapses during short or long-term periods characterized by worsening of muscle weakness sometimes associated with respiratory crises are described. All the relapses ended spontaneously or with 3-4 DAP or ephedrine with no residual impairment. The triggering factors identified were esterase inhibitors, effort, puberty or pregnancy highlighting the importance of hormonal factors. There was no genotype-phenotype correlation. At the end of the follow-up, 80% of patients were ambulant and 87% of patients had no respiratory trouble in spite of severe relapses.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5688.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5687.phpUse of complementary and alternative medicine by males with Duchenne or Becker muscular dystrophy was examined using interview reports from caregivers enrolled in the population-based Muscular Dystrophy Surveillance, Tracking, and Research Network. Of the 200 caregivers interviewed, 160 (80%) reported "ever" using complementary and alternative medicine for their affected children. Mind-body medicine (61.5%) was most frequently used, followed by biologically based practices (48.0%), manipulative and body-based practices (29.0%), and whole medical systems (8.5%). Caregivers reporting use of whole medical systems had higher education and income levels compared with nonusers; affected males had shorter disease duration. Caregivers reporting use of mind-body medicine, excluding aquatherapy, had higher education level compared with nonusers. Overall, complementary and alternative medicine use was high; disease duration, education, and income levels influenced use. These findings have implications for developing clinical care protocols and monitoring possible interactions between complementary and alternative medicine and conventional medical therapies.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5687.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5686.phpSpinal muscular atrophy (SMA) is characterized by proximal weakness caused by loss of motor neurons in the anterior horn and homozygous deletion of the SMN1 gene. SMA is classified according to age of onset and acquired motor milestones. Treatment of SMA is supportive as there is no known efficacious drug treatment. Using Cochrane methodology, Dr. Wadman and colleagues systematically evaluated all randomized controlled trials on the efficacy of drug treatment to slow or arrest disease progression of SMA types 1–3. Of 22 eligible studies, 7 trials fulfilled the selection criteria. One underpowered trial that included 10 patients with SMA type 1 showed no effect of riluzole treatment on survival and mortality. Efficacy of treatment for SMA types 2/3 was evaluated in 6 trials. A trial with negative results investigated treatment with phenylbutyrate in 107 patients with SMA type 2. One trial included 61 non-ambulatory patients and did not demonstrate an effect of polytherapy with valproate and acetyl-L-carnitine. An underpowered trial of 9 patients with intravenous thyrotropin releasing hormone showed improvement of motor function in some patients. Treatment with gabapentin in a trial including 84 adult patients did not show any efficacy. Efficacy was not established for hydroxyurea treatment in a trial with 57 patients. Creatine therapy showed no effect in a trial with 55 patients. There is no known efficacious drug treatment for SMA types 1–3. Although open and uncontrolled treatment trials had seemed promising, none of the seven included randomized controlled trials showed a significant effect on any of the outcome measures.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5686.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5685.phpDuchenne muscular dystrophy is caused by mutations in the DMD gene that disrupt the open reading frame and prevent the full translation of its protein product, dystrophin. Restoration of the open reading frame and dystrophin production can be achieved by exon skipping using antisense oligonucleotides targeted to splicing elements. This approach aims to transform the Duchenne muscular dystrophy phenotype to that of the milder disorder, Becker muscular dystrophy, typically caused by in-frame dystrophin deletions that allow the production of an internally deleted but partially functional dystrophin. There is ongoing debate regarding the functional properties of the different internally deleted dystrophins produced by exon skipping for different mutations; more insight would be valuable to improve and better predict the outcome of exon skipping clinical trials. To this end, the authors of this study have characterized the clinical phenotype of 17 patients with Becker muscular dystrophy harbouring in-frame deletions relevant to on-going or planned exon skipping clinical trials for Duchenne muscular dystrophy and correlated it to the levels of dystrophin, and dystrophin-associated protein expression. The cohort of 17 patients, selected exclusively on the basis of their genotype, included 4 asymptomatic, 12 mild and 1 severe patient. All patients had dystrophin levels of >40% of control and significantly higher dystrophin (P=0.013), â-dystroglycan (P = 0.025) and neuronal nitric oxide synthase (P = 0.034) expression was observed in asymptomatic individuals versus symptomatic patients with Becker muscular dystrophy. Furthermore, grouping the patients by deletion, patients with Becker muscular dystrophy with deletions with an end-point of exon 51 (the skipping of which could rescue the largest group of Duchenne muscular dystrophy deletions) showed significantly higher dystrophin levels (P = 0.034) than those with deletions ending with exon 53. This is the first quantitative study on both dystrophin and dystrophin-associated protein expression in patients with Becker muscular dystrophy with deletions relevant for on-going exon skipping trials in Duchenne muscular dystrophy. Taken together, these results indicate that all varieties of internally deleted dystrophin assessed in this study have the functional capability to provide a substantial clinical benefit to patients with Duchenne muscular dystrophy.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5685.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5684.phpIn boys with Duchenne muscular dystrophy (DMD), (1)H MRI suggested muscular oedema before fatty degeneration. Using specific (23)Na MRI sequences,  the authors tested the hypothesis that the oedema is caused by an osmotic effect due to increased myoplasmic Na(+) content rather than inflammation that would lead to extracellular oedema. Eleven patients with DMD (mean age, 10 ± 5 years) and 16 healthy volunteers of similar age were examined on a 3-T system with (1)H MRI and (23)Na density-adapted 3-dimensional radial MRI sequences. The muscle oedema was quantified on short-tau inversion recovery images using background noise as reference. Fatty degeneration was quantified on T1-weighted images using subcutaneous fat as reference. Na(+) was quantified by a muscular tissue sodium concentration (TSC) sequence. A novel inversion recovery (IR) sequence allowed the authors to determine mainly the myoplasmic Na(+) by suppression of the extracellular (23)Na signal from vasogenic oedema. A reference tube containing 51.3 mmol/L Na(+) with agarose gel was used for standardisation. The normalised muscular signal intensity of (23)Na as assessed by the IR sequence was significantly higher for patients with DMD than for volunteers. TSC was markedly increased at 38.4 ± 6.8 mmol/L in patients with DMD compared with 25.4 ± 2.1 mmol/L in volunteers. The muscular oedema-like changes were much more prominent in patients with DMD than in volunteers. In addition, the muscular fat content was significantly higher in patients with DMD than in volunteers. The elevated myoplasmic Na(+) concentration in DMD is osmotically relevant and causes a mainly intracellular muscle oedema that contributes to the pathogenesis of DMD.Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5684.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5683.phpThe ALS Therapy Development Institute (ALS TDI), a non-profit biotechnology organisation dedicated to developing effective treatments for amyotrophic lateral sclerosis (ALS), will collaborate with two major biotechnology companies to investigate a potential treatment that modulates the immune system. The experimental treatment is an antibody fragment dubbed CDP7657. It will be tested in mice with a mutation in the SOD1 gene, one of the causes of familial ALS in humans and of an ALS-like disease in mice. The two multinational biotechnology companies are Biogen Idec, headquartered in Weston, Mass., and UCB, based in Brussels, Belgium. The mouse version of CDP7657 that will be used in these experiments targets a protein called CD40L, found on the surface of T cells. The compound interferes with the ability of the CD40L protein to engage with other proteins and launch a full-blown immune response. A human version of CDP7657 is being tested in a phase 1 clinical trial for lupus, an autoimmune disease. Mounting evidence suggests that ALS is also an autoimmune disorder. A webinar discussion of the ALS TDI-Biogen Idec-UCB research agreement will take place Jan. 5, 2012, at 1 p.m. ET. Anyone can participate, but registration is required. Thu, 29 Dec 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5683.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5675.phpThe effect of an interval exercise training (ITE) program on heart rate variability (HRV) was studied in 8 patients with Charcot-Marie-Tooth (CMT) disease and 8 healthy controls. At baseline, all subjects underwent ambulatory 24-hour Holter electrocardiographic (ECG) monitoring to evaluate HRV. HRV analysis was repeated on CMT patients after they completed a 24-week ITE program on a cycle ergometer. Before exercise, all HRV indices were lower in patients compared with controls, and the difference reached statistical significance for pNN50 (percent of differences between adjacent R-R intervals exceeding 50 ms). After ITE, time- and frequency-domain indices were significantly improved, particularly at night (+8% mean R-R interval, +95% pNN50, 52% reduction in low/high-frequency ratio). The authors observed significant increases in some of the time and frequency parameters, and values sometimes exceeded those of controls at baseline. These results suggest that ITE improves HRV modulation in CMT patients by enhancing parasympathetic activity.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5675.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5674.phpThis study assessed implant rates, indications, characteristics, and outcomes in patients with the neuromuscular disease, myotonic dystrophy type 1 (DM1) receiving a pacemaker or an implantable cardioverter-defibrillator (ICD). Device use was evaluated in a prospective, multicenter registry of 406 genetically confirmed adult patients followed for 9.5 ± 3.2 years. Forty-six (11.3%) had or received a pacemaker and 21 (5.2%) received an ICD. Devices were primarily implanted for asymptomatic conduction abnormalities and left ventricular (LV) systolic dysfunction. However, 7 (15.2%) pacemakers were implanted for third-degree atrioventricular block and 6 (28.6%) ICDs were implanted for ventricular tachyarrhythmias (ventricular tachycardia [VT] or fibrillation [VF]). Patients receiving devices were older and more frequently had heart failure, LV systolic dysfunction, atrial tachyarrhythmias, and ECG conduction abnormalities compared to nondevice patients. Five (10.9%) pacemaker patients underwent upgrade to an ICD, 3 for LV systolic dysfunction, 1 for VT/VF, and 1 for progressive conduction disease. Seventeen (27.4%) of the 62 patients with devices were pacemaker-dependent at last follow-up. Three (14.3%) ICD patients had appropriate therapies. Twenty-four (52.2%) pacemaker patients died including 13 of respiratory failure and 7 of sudden death. Seven (33.3%) ICD patients died including 2 of respiratory failure and 3 of sudden death. The patients with ICDs and sudden death all had LV systolic dysfunction and 1 death was documented due to inappropriate therapies. Myotonic dystrophy Type 1 patients commonly receive antiarrhythmia devices. The risk of VT/VF and sudden death suggests that ICDs rather than pacemakers should be considered for these patients.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5674.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5673.phpLimb-girdle muscular dystrophy type 2A (LGMD2A) is caused by a deficiency of calpain-3/p94. Although the symptoms in most LGMD2A patients are generally homogeneous, some variation in the severity and progression of the disease has been reported. This study describes 2 patients who carry the same combination of compound heterozygous mutations (pG222R/pR748Q) and whose symptoms are exceptionally benign compared to homozygotes with each missense mutation. The benign phenotype observed in association with the combined pG222R and pR748Q mutations suggested that it may result from a compensatory effect of compound heterozygosity rather than the individual mutations themselves. Analyses revealed that these two mutations exert different effects on the protease activity of calpain-3, suggesting “molecular complementation” in these patients. The authors propose several hypotheses to explain how this specific combination of mutations may rescue the normal proteolytic activity of calpain-3, resulting in an exceptionally benign phenotype. Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5673.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5672.phpThe presence of non-progressive cognitive impairment is recognized as a common feature in a substantial proportion of patients with Duchenne muscular dystrophy. Interestingly, delay in global developmental and language disorders can constitute the signs of onset in this disease. A lack of the 140-kDa brain protein isoform called Dp140 is thought to play a significant role in cognitive performances in both Duchenne muscular dystrophy and Becker muscular dystrophy. However, apart from general intellectual abilities, a lack of consensus exists on the correlation between dysfunction in the dystrophin gene and a specific neuropsychologic profile. The present study investigated possible similarities and differences in the cognitive profiles of 42 Italian-speaking, school-age children with Duchenne muscular dystrophy, with different mutation sites along the dystrophin gene, i.e., distal vs proximal (downstream and upstream from exon 44, involving or sparing the expression of Dp140, respectively). The children underwent a battery of tests tapping a wide range of intellectual, linguistic, and neuropsychologic functions. Full-scale intelligence quotient was approximately 1 S.D. below the population average in the whole group of dystrophic children. Patients with Duchenne muscular dystrophy and mutations located in the distal portion of the dystrophin gene (involving Dp140) were generally more severely affected and expressed different patterns of strengths and impairments, compared with patients with Duchenne muscular dystrophy and mutations located in the proximal portion of the dystrophin gene (not involving Dp140). Patients with Duchenne muscular dystrophy and distal mutations demonstrated specific impairments in visuospatial functions and visual memory (which seemed intact in proximally mutated patients) and greater impairment in syntactic processing.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5672.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5671.phpDuchenne Muscular Dystrophy (DMD), a lethal X-linked disorder, is the most common and severe form of muscular dystrophies, affecting 1 in 3500 male births. Mutations in the DMD gene lead to the absence of muscle dystrophin and a progressive degeneration of skeletal muscle. The possibility to treat DMD through cell therapy has been widely investigated. The authors of this study have previously shown that human Adipose-derived Stromal Cells (hASCs) injected systemically in SJL mice are able to reach and engraft in the host muscle, express human muscle proteins and ameliorate the functional performance of injected animals without any immunosuppression. However before starting clinical trials in humans many questions still need to be addressed in preclinical studies, in particular in larger animal models, when available. The best animal model to address these questions is the Golden Retriever Muscular Dystrophy (GRMD) dog that reproduces the full spectrum of human DMD. Affected animals carry a mutation that predicts a premature termination codon in exon 8 and a peptide that is 5% the size of normal dystrophin. These dogs present clinical signs within the first weeks and most of them do not survive beyond age two. Herein, the results of local and intravenous injections of hASCs into GRMD dogs, without immunosuppression are described. hASCs injected systemically into the dog cephalic vein are able to reach, engraft, and express human dystrophin in the host GRMD dystrophic muscle up to 6 months after transplantation. Most importantly the authors demonstrate that injecting a huge quantity of human mesenchymal cells in a large animal model, without immunosuppression, is a safe procedure, which may have important applications for future therapy in patients with different forms of muscular dystrophies.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5671.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5670.phpThe authors of this study examined the factors that contribute to resiliency in children living with Duchenne muscular dystrophy (DMD), a chronic, progressive neuromuscular disorder that also influences cognitive ability. They hypothesized that family and social support will moderate the effects of individual symptoms of illness severity and influence positive adjustment in boys with DMD. One hundred forty-six boys with DMD were included in this study. Child adjustment, as determined by parent ratings of their son's behaviour using the Total Behaviour score from the Child Behaviour Checklist (CBCL), was examined as an outcome measure. The contributions of individual variables (including age [which serves also as a proxy for degree of physical disability], wheelchair use, and estimated verbal IQ), family variables (the Parental Distress score from the Parent Stress Index), and social environment variables (the Social Competence score from the CBCL) on child adjustment were examined in a linear regression analysis. Both family and social environment variables significantly contributed to the variance in the CBCL Total Behaviour score. In contrast, individual factors that are related to illness severity (age, degree of physical involvement, and estimated verbal IQ) were not associated with child adjustment. Increased children's social networks and decreased parents' stress levels positively contributed to good child adjustment, whereas degree of individual clinical severity did not. Thus, emphasis on providing opportunities for friendships and social support and on parents' adjustment will aid in children's resilience, ensuring they can live well, even while living with the significant burdens associated with DMD.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5670.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5669.phpBoys with Duchenne muscular dystrophy (DMD) are currently treated with corticosteroids at a young age to prolong ambulation. This therapy combined with improvements in respiratory care have resulted in increased survival such that DMD-associated heart disease is now the leading cause of mortality. Despite reports in small cohorts of the beneficial cardiovascular effects of corticosteroids and angiotensin converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB), there is no consensus regarding the management of DMD-associated cardiac disease. In the absence of conclusive randomized clinical trial data, steroids, ACEI, ARB, beta blockers (BB) and/or digoxin have been used empirically. Defining clinical endpoints for cardiac therapy in DMD boys is challenging. Recent studies have shown that indices of global left ventricular (LV) function are not adequate to detect cardiac dysfunction in young DMD patients, but myocardial strain (ĺ), an indicator of local myocardial deformation normalized to its original dimension, can detect occult cardiac disease early in the course of DMD despite normal ejection fraction (EF). Further, depressed ĺcc magnitude correlates with disease progression. The purpose of this study was to retrospectively compare cardiac effects of corticosteroid monotherapy versus corticosteroids plus ACEI or ARB in a cohort of DMD patients. The effects on both global LV function (EF) and local LV function (ĺcc) determined by cardiovascular magnetic resonance (CMR) were compared. CMR was used to assess effects of corticosteroids alone (Group A) or in combination with ACEI or ARB (Group B) on heart rate (HR), left ventricular ejection fraction (LVEF), mass (LVM), end diastolic volume (LVEDV) and circumferential strain (ĺcc) in a cohort of 171 DMD patients >5 years of age. Patients in Group A (114 studies) were younger than those in Group B (92 studies)(102.4 vs. 12.43.2 years, p< 0.0001), but HR, LVEF, LVEDV and LVM were not different. Although ĺcc magnitude was lower in Group B than Group A (-13.81.9 vs. -12.82.0, p= 0.0004), age correction using covariance analysis eliminated this effect. In a subset of patients who underwent serial CMR exams with an inter-study time of ~15 months, cc worsened regardless of treatment group. These results support the need for prospective clinical trials to identify more effective treatment regimens for DMD associated cardiac disease.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5669.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5668.phpDuchenne muscular dystrophy (DMD) is a devastating X-linked muscle wasting disease, caused by mutations in the dystrophin gene. Dystrophin provides structural integrity to skeletal and cardiac muscle via the dystrophin associated protein complex (DAPC). In the absence of dystrophin, the entire DAPC is lost from the sarcolemma. For patients, DMD leads to progressive muscle weakness, dependence on a wheelchair, respiratory and cardiac complications and a shortened lifespan. There is currently no effective treatment available. Utrophin is an autosomal homologue of dystrophin that can also bind to proteins of the DAPC. Dystrophin and utrophin share 74% similarity at the amino acid level and have very similar domain structures. Studies in mdx mice, a model for DMD, have shown that utrophin, when overexpressed in myofibres by viral vector-mediated delivery or by transgenic means, can compensate for the absence of dystrophin, restoring normal muscle function. It is also worth noting that, because utrophin is expressed in foetal muscle and in various non-muscle tissues in the adult, its overexpression in the muscles of people with DMD is unlikely to provoke an immune response. Although utrophin upregulation is an attractive therapeutic approach for DMD, no such therapy is yet available for clinical use in DMD patients. The use of a small, drug-like molecule to achieve utrophin upregulation offers obvious advantages in terms of delivery and bioavailability. Furthermore, much of the time and expense involved in the development of a new drug can be eliminated by screening molecules that are already approved for clinical use. In this study, the authors have developed and validated a cell-based, high-throughput screening assay for utrophin promoter activation, and used it to screen the Prestwick Chemical Library of marketed drugs and natural compounds. Initial screening produced 20 hit molecules, 14 of which exhibited dose-dependent activation of the utrophin promoter and were confirmed as hits. Independent validation demonstrated that one of these compounds, nabumetone, is able to upregulate endogenous utrophin mRNA and protein, in C2C12 muscle cells. The pharmacokinetics and safety in humans of nabumetone are already well described and represents a lead compound for utrophin upregulation as a therapy for DMD.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5668.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5667.phpUllrich congenital muscular dystrophy (UCMD) is an autosomal recessive disorder, affecting connective tissue and skeletal muscle, characterized by generalized muscle wasting and weakness, and by the unusual combination of contractures of proximal joints and hyperflexibility of distal joints. Mutations in the alpha 2 and alpha 3 chain genes of collagen VI cause UCMD although genetic heterogeneity is possible. In this study, six individuals with UCMD and mutations in the genes-encoding collagen VI, aging 5-9, received 3-5 mg/kg of cyclosporine A (CsA) daily for 1 to 3.2 years. The primary outcome measure was the muscle strength evaluated with a myometer and expressed as megalimbs. The megalimbs score showed significant improvement (P = 0.01) in 5 of the 6 patients. Motor function did not change. Respiratory function deteriorated in all. CsA treatment corrected mitochondrial dysfunction, increased muscle regeneration, and decreased the number of apoptotic nuclei. Results from this study demonstrate that long-term treatment with CsA ameliorates performance in the limbs, but not in the respiratory muscles of UCMD patients, and that it is well tolerated. These results suggest considering a trial of CsA or nonimmunosuppressive cyclosporins, that retains the PTP-desensitizing properties of CsA, as early as possible in UCMD patients when the diaphragm is less compromised.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5667.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5666.phpThe genetic variation underlying facioscapulohumeral muscular dystrophy (FSHD), 1 of the most common hereditary neuromuscular disorders, is complex, and associated with the contraction of a repeat array (D4Z4) at the subtelomeric end of chromosome 4q. Non-pathogenic variants of 4q and the presence of a homologous array on chromosome 10q make FSHD diagnosis extremely challenging, at least in individuals with nonstandard D4Z4 arrays. This article describes the visualisation of specific haplotypes from multiple independent DNA molecules to explore FSHD, one of the most common forms of muscular dystrophy. Over the last decade, major advances have contributed to the understanding of the complex genetics underlying this disorder. Despite these advances, accurately diagnosing FSHD in patients is still very challenging and the disease is commonly misdiagnosed. In addition to this, the mechanisms leading to atrophy and weakness remain unclear. The purpose of this study was to develop a new method to directly visualise the different genomic elements involved in FSHD pathogenesis, leading to an efficient and validated test to explore FSHD both in a diagnosis and research context. The technique of molecular combing (MC) was employed, which enables high-resolution single DNA molecule analysis by fluorescence. By performing a single fluorescent in situ hybridisation on combed DNA, the position of specially designed probes can be directly visualised at 1 kilobase pair resolution, providing a means to construct physical genomic maps and detect micro-rearrangements. Molecular combing was originally developed to map genes and has also been used to study DNA replication. This article reports the first application of MC to explore and diagnose a mendelian disease. This approach not only allowed firm conclusions in 100% of FSHD patients, but also allowed to characterize mosaics, unreported haplotypes and unexpected rearrangements. Complete allelic composition and distribution at 4q35 and 10q26 was determined for each of the FSHD patients explored in this study. MC for FSHD diagnosis appears both feasible and adequate as a new tool to explore FSHD associated loci and to precise their allelic composition. It could become the "gold standard" approach for FSHD diagnosis. Besides, the MC test provides invaluable information on the physical organization of the 4q35 genomic region, which was so far unreachable with other techniques. While FSHD is the 1st genomic disease to benefit MC, other rare genetic diseases, such as those associated to repeats number variants, could benefit from this approach in the future.Sun, 20 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5666.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5591.phpSpinocerebellar ataxia type 1 (SCA1) is an adult-onset, dominantly inherited neurodegenerative disease caused by expansion of a glutamine repeat tract in ataxin-1 (ATXN1). Although the precise function of ATXN1 remains elusive, it seems to be involved in transcriptional repression. In this study, a research team has found that VEGF expression is depressed in the affected brain regions of a mouse model of SCA1, due to the activity of ATXN1. The team subsequently found that SCA1 pathology could be reduced and motor function improved in mice engineered to overexpress VEGF, or those that were treated using intracerebellar administration of VEGF. Transcriptional changes are one of the earliest pathogenic signatures in SCA1 mouse models, indicating that dysregulated gene expression caused by mutant ATXN1 is central to the pathogenesis of SCA1, the researchers explain. However, the direct targets of ATXN1-induced repression, particularly in the most vulnerable Purkinje cell population in the cerebellum, haven't been identified. The team used laser-capture microdissection (LCM) to isolate Purkinje neurons from SCA1 knock-in mice, and undertake PCR to further study gene expression dysregulation in the disease by examining the expression of candidate genes involved in key neurodegenerative pathways. They found that one of the genes downregulated in SC1A encodes VEGFA, an angiogenic and neurotrophic factor implicated in motor neuron disorders. The animals exhibited decreased VEGFA mRNA levels as early as postnatal day 30, which is before any pathological signs of the disease become manifest. In fact, the level of decrease in VEGFA mRNA was greater than that of three other genes-Gsbs, Homer3, and Slc1a6, which previous research had shown were downregulated in SCA1. Further analysis showed that levels of VEGF protein were 30% less in SCA1 cerebella than in wild-type cerebella, and the decrease was most prominent in Purkinje neurons. The team went on to use a VEGFA luciferase reporter assay to see whether mutant ATXN1 directly affects VEGFA mRNA expression by modulating promoter activity. Interestingly, both the mutant ATXN1 (ATXN1-84Q) and wild-type ATXN1 (ATXN1-2Q) repressed reported activity. The fact that VEGF is an angiogenic factor pointed to the probability that reduced levels could contribute to cerebellar dysfunction by limiting angiogenesis. Indeed, the researchers found that cerebellar microvessel density and vessel length were both depressed in SCA1 mice, and there was additional evidence of hypoxia. Separate studies on normal mixed cerebellar neuronal cultures that express VEGF and its receptor VEGFR2 demonstrated that antibody- or inhibitor-mediated blockage of VEGF or VEGFR2, respectively, resulted in decreased neurite length and increased cell death. The team finally evaluated the effects of restoring VEGF expression in SCA1 mice either by increasing VEGF gene expression, or administering exogenous VEGF directly to the brain. Transgenic SCA1 mice that also overexpressed human VEGF in neurons demonstrated significantly enhanced motor performance at 13 weeks and 6 months of age, and exhibited improved cerebellar pathology including cerebellar microvessel density. Similarly, continuously delivering mouse VEGF to SCA1 animals using an intracerebroventricular osmotic pump also improved motor performance and restored cerebellar pathology. This findings suggest a role for VEGF in SCA1 pathogenesis and indicate that restoring VEGF levels may be a potentially useful treatment in patients with SCA1. Moreover, they suggest that alterations in VEGF itself or sequelae of VEGF signaling in blood or cerebrospinal fluid of affected individuals could prove to be a biomarker of disease progression.Thu, 03 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5591.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5590.phpThe lack of effective drug therapies for motor neuron diseases (MND), and in general for all the neurodegenerative disorders, has increased the interest toward the potential use of stem cells. Among the cell therapy approaches so far tested in MND animal models, systemic injection of human cord blood mononuclear cells (HuCB-MNCs) has proven to reproducibly increase, although modestly, the life span of SOD1G93A mice, a model of familial amyotrophic lateral sclerosis (ALS), even if only few transplanted cells were found in the damaged areas. In attempt to improve the potential efficacy of these cells in the central nervous system, the authors of the present study examined the effect and distribution of Hoechst 33258-labeled HuCB-MNCs after a single bilateral intracerberoventricular injection in two models of motor neuron degeneration, the transgenic SOD1G93A and wobbler mice. HuCB-MNCs significantly ameliorated symptoms progression in both mouse models and prolonged survival in SOD1G93A mice. They were localized in the lateral ventricles, even 4 months after administration. However, HuCB-MNCs were not found in the spinal cord ventral horns. This evidence strengthens the hypothesis that the beneficial role of transplanted cells is not due to cell replacement but is rather associated with the production and release of circulating protective factors that may act both at the central and/or peripheral levels. In particular, it was demonstrated that HuCB-MNCs release a series of cytokines and chemokines with antiinflammatory properties that could be responsible for the functional improvement of mouse models of motor neuron degenerative disorders.Thu, 03 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5590.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5589.phpCongenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous group of inherited disorders of the neuromuscular junction. A difficult to diagnose subgroup of CMS is characterised by proximal muscle weakness and fatigue while ocular and facial involvement is only minimal. DOK7 mutations have been identified as causing the disorder in about half of the cases. More recently, using classical positional cloning, the authors of the present study had identified mutations in a previously unrecognised CMS gene, GFPT1, in a series of DOK7-negative cases. In this study, the authors now describe the clinical picture of 24 limb-girdle CMS (LG-CMS) patients and pathological findings of 18 of them, all carrying GFPT1 mutations. Additional patients with CMS, but without tubular aggregates, and patients with non-fatigable weakness with tubular aggregates were also screened. In most patients with GFPT1 mutations, onset of the disease occurs in the first decade of life with characteristic limb-girdle weakness and fatigue. A common feature was beneficial and sustained response to acetylcholinesterase inhibitor treatment. Most of the patients who had a muscle biopsy showed tubular aggregates in myofibers. Analysis of endplate morphology in one of the patients revealed unspecific abnormalities. This study delineates the phenotype of CMS associated with GFPT1 mutations and expands the understanding of neuromuscular junction disorders. As tubular aggregates in context of a neuromuscular transmission defect appear to be highly indicative, the authors suggest calling this condition congenital myasthenic syndrome with tubular aggregates (CMS-TA).Thu, 03 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5589.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5588.phpFukuyama muscular dystrophy (FCMD; MIM253800), one of the most common autosomal recessive disorders in Japan, was the first human disease found to result from ancestral insertion of a SINE-VNTR-Alu (SVA) retrotransposon into a causative gene. In FCMD, the SVA insertion occurs in the 3' untranslated region (UTR) of the fukutin gene. The pathogenic mechanism for FCMD is unknown, and no effective clinical treatments exist. Herein, researchers show that aberrant messenger RNA (mRNA) splicing, induced by SVA exon-trapping, underlies the molecular pathogenesis of FCMD. Quantitative mRNA analysis pinpointed a region that was missing from transcripts in patients with FCMD. This region spans part of the 3' end of the fukutin coding region, a proximal part of the 3' UTR and the SVA insertion. Correspondingly, fukutin mRNA transcripts in patients with FCMD and SVA knock-in model mice were shorter than the expected length. Sequence analysis revealed an abnormal splicing event, provoked by a strong acceptor site in SVA and a rare alternative donor site in fukutin exon 10. The resulting product truncates the fukutin carboxy (C) terminus and adds 129 amino acids encoded by the SVA. Introduction of antisense oligonucleotides (AONs) targeting the splice acceptor, the predicted exonic splicing enhancer and the intronic splicing enhancer prevented pathogenic exon-trapping by SVA in cells of patients with FCMD and model mice, rescuing normal fukutin mRNA expression and protein production. AON treatment also restored fukutin functions, including O-glycosylation of á-dystroglycan (á-DG) and laminin binding by á-DG. Moreover, exon-trapping in other SVA insertions associated with disease (hypercholesterolemia, neutral lipid storage disease) and human-specific SVA insertion in a novel gene were observed. Thus, although splicing into SVA is known, this study unveiled a role for SVA-mediated exon-trapping in human disease and demonstrated the promise of splicing modulation therapy as the first radical clinical treatment for FCMD and other SVA-mediated diseases.Thu, 03 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5588.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5587.phpIn this study the authors aimed to identify the genetic and epigenetic defects in patients presenting with a facioscapulohumeral (FSHD) clinical phenotype without D4Z4 contractions on chromosome 4q35 tested by linear gel electrophoresis and Southern blot analysis. Sixteen patients displaying an FSHD-like phenotype, with normal cardiovascular and respiratory function, a myopathic pattern on electromyography, and a muscle biopsy being normal or displaying only mild and aspecific dystrophic changes were studied. The authors sequenced the genes calpain 3 (CAPN3), valosin containing protein (VCP) and four-and-a-half LIM domains protein 1 (FHL1), and analysed the D4Z4 repeat arrays by extensive genotyping and DNA methylation analysis. They  identified one patient carrying a complex rearrangement in the FSHD locus that masked the D4Z4 contraction associated with FSHD1 in standard genetic testing, one patient with somatic mosaicism for the D4Z4 4q35 contraction, six patients that were diagnosed as having FSHD2, four patients with CAPN3 mutations and two patients with a VCP mutation, No mutations were detected in FHL1, and in two patients, the authors could not identify the genetic defect. In patients presenting with an FSHD-like clinical phenotype with a negative molecular testing for FSHD, the following should be taken into consideration: i) detailed genetic testing including D4Z4 contraction of permissive hybrid D4Z4 repeat arrays, p13E-11 probe deletions, and D4Z4 hypomethylation in the absence of repeat contraction as observed in FSHD2; ii) mutations in CAPN3 even in the absence of protein deficiency on western blot analysis; and iii) VCP mutations even in the absence of cognitive impairment Paget disease and typical inclusion in muscle biopsy.Thu, 03 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5587.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5586.phpSpinal muscular atrophy (SMA) is an inherited neuromuscular disorder that causes degeneration of á-motor neurons. Frequently, muscle weakness is very severe causing affected infants to die before reaching two years of age, but mild forms of the disease can be characterized by relatively static muscle weakness for many years. SMA is caused by recessive mutations of the SMN1 gene, but all patients retain at least one copy of SMN2, a similar gene capable of producing low levels of full-length SMN protein. No treatments currently exist for SMA patients, but the identification of therapeutic targets and the development of suitable animal models for preclinical testing have resulted in increased drug development efforts in the past ten years. In this study researchers have evaluated the effects of restoring SMN protein in peripheral tissues, including liver and cardiac tissues, in mouse models of SMA. They used an approach that involved administering an antisense oligonucleotide (ASO), ASO-10-27 that corrects SMN2 splicing and restores SMN protein expression in motor neurons and other tissues and organs, in particular the liver. Systemic administration of ASO-10-27 to neonates robustly rescued severe SMA mice, much more effectively than intracerebroventricular administration; subcutaneous injections extended the median lifespan by 25 fold. Furthermore, neonatal SMA mice had decreased hepatic Igfals expression, leading to a pronounced reduction in circulating insulin-like growth factor 1 (IGF1), and ASO-10-27 treatment restored IGF1 to normal levels. These data indicate that restoring SMN in peripheral tissues, in combination with partial restoration in the CNS, can dramatically improve many clinical features of SMA in this severe mouse model of SMA. This research suggests that in this mouse model of severe SMA there may be a therapeutic benefit from an increase in functional SMN protein in tissues outside of the central nervous system. Additional studies are needed to determine if these finding have any relevance in patients with severe SMA.Thu, 03 Nov 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5586.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5549.php Duchenne muscular dystrophy (DMD) is an incurable genetic disease with early mortality. Multipotent mesenchymal stromal cells (MSCs) are potentially interesting therapeutics, because they can be transplanted to muscle tissue and differentiated to form myogenic cells in situ. In this study, the authors have developed different strategies for effective cell transplantation into the dystrophic dog. Canine CD271-(+) MSCs obtained from donor bone marrow cells were enriched by immunomagnetic isolation. The dog leukocyte antigens (DLA) were analyzed to determine DLA- identical mating pairs to achieve donor or recipient of allogeneic transplantation. Cardiotoxin (CTX) was injected into the tibialis anterior (TA) muscles of normal Beagle dogs 5 days before MSCs injection. CD271+ MSCs transduced with an adenoviral vector expressing MyoD (Ad-MyoD) were injected into the TA muscles of recipient canine X-linked muscular dystrophy in Japan (CXMDJ) without immunosuppression. For intra-arterial injection, MyoD-transduced CD271+ MSCs were administered into the femoral artery with transient avascularisation using a tourniquet followed by the injection of papaverin hydrochloride. The treated muscles were biopsied and analysed histologically. Autologous CD271+ MSCs were transduced with AAV-microdystrophin and administrated into the TA muscles of DMD dog. CD271+ MSCs obtained from the normal Beagle dog showed greater growth expansion compared with CD271-depleted MSCs. MyoD transduction of CD271+ MSCs caused myogenic differentiation in vitro and myotube formation with late myogenic markers expression. Without immunosuppression, CD271+ MSCs in the myogenic cell lineage were transplanted into DLA-identical CXMDJ and formed clusters of muscle-like tissue at 8 and 12 weeks after the intra-muscular injection. The engraftment of CD271+ MSCs was also found at the site of CTX-injured muscle after the intra-arterial injection. Interestingly, CD271+ MSCs engraftment was improved with papaverin hydrochloride pre-treatment. Immunohistological analysis suggested that CD271+ MSCs formed muscle-like tissues and exhibited upregulation of developmental myosin heavy chain as well as dystrophin without inflammatory cell infiltration. Furthermore, CD271+ MSCs derived from CXMDJ also showed myotube formation in vitro by the expression of microdystrophin. MyoD-transduced CD271+ MSCs enabled more efficient MSC transplantation via the intra-muscular as well as intra-arterial administration routes. This strategy of MSCs propagation may offer a promising treatment approach for patients with DMD.Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5549.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5548.phpPompe disease is a lysosomal storage disorder characterized by progressive muscle weakness. With the emergence of new treatment options, psychometrically robust outcome measures are needed to monitor patients' clinical status. In this study, the authors have constructed a motor function test that is easy and quick to use. The Quick Motor Function Test (QMFT) was constructed on the basis of the clinical expertise of several physicians involved in the care of Pompe patients; the Gross Motor Function Measure and the IPA/Erasmus MC Pompe survey. The test comprises 16 items. Validity and test reliability were determined in a cohort of 91 Pompe patients (5 to 76 years of age). In addition, responsiveness of the scale to changes in clinical condition over time was examined in a subgroup of 18 patients receiving treatment and 23 untreated patients. Interrater and intrarater reliabilities were good (intraclass correlation coefficients: 0.78 to 0.98 and 0.76 to 0.98). The test correlated strongly with proximal muscle strength assessed by hand held dynamometry and manual muscle testing (rs= 0.81, rs=0.89), and showed significant differences between patient groups with different disease severities. A clinical-empirical exploration to assess responsiveness showed promising results, albeit it should be repeated in a larger group of patients. In conclusion, the Quick Motor Function Test can reliably rate clinical severity and motor function in children and adults with Pompe disease.Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5548.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5547.phpMutations in the CRYAB gene, encoding alpha-B crystallin, cause distinct clinical phenotypes including isolated posterior polar cataract, myofibrillar myopathy, cardiomyopathy, or a multisystemic disorder combining all these features. Genotype/phenotype correlations are still unclear. To date, multisystemic involvement has been reported only in kindred harboring the R120G substitution. This study reports a novel CRYAB mutation, D109H, associated with posterior polar cataract, myofibrillar myopathy and cardiomyopathy in a two-generation family with five affected individuals. Age of onset, clinical presentation, and muscle abnormalities were very similar to those described in the R120G family. Alpha-B crystallin may form dimers and acts as a chaperone for a number of proteins. It has been suggested that the phenotypic diversity could be related to the various interactions between target proteins of individual mutant residues. Molecular modeling indicates that residues D109 and R120 interact with each other during dimerization of alpha-B crystallin; interestingly, the two substitutions affecting these residues (D109H and R120G) are associated with the same clinical phenotype, thus suggesting a similar pathogenic mechanism. The authors propose that impairment of alpha-B crystallin dimerization may also be relevant to the pathogenesis of these disorders. Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5547.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5546.phpFacioscapulohumeral muscular dystrophy (FSHD) is a dominant disease linked to contraction of an array of tandem 3.3-kb repeats (D4Z4) at 4q35. Within each repeat unit is a gene, DUX4, that can encode a protein containing two homeodomains. A DUX4 transcript derived from the last repeat unit in a contracted array is associated with pathogenesis but it is unclear how. Using exon-based microarrays, the expression profiles of myogenic precursor cells were determined. Both undifferentiated myoblasts and myoblasts differentiated to myotubes derived from FSHD patients and controls were studied after immunocytochemical verification of the quality of the cultures. To gain further insight into FSHD and normal myogenesis, the expression profiles obtained were compared to those of 19 non-muscle cell types analyzed by identical methods. Many of the ~17,000 examined genes were differentially expressed (>2-fold, pThu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5546.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5545.phpThe relationships between the Expanded Hammersmith Functional Motor Scale (HFMSE) and genotype and motor and respiratory outcomes were examined in patients with spinal muscular atrophy types II and III (n = 70). The correlation between the HFMSE and Gross Motor Function Measure was r = 0.98. Correlations between HFMSE and forced vital capacity (percentage of predicted normal) (n = 56) and a functional rating (n = 57) were r = 0.87 and r = 0.92, respectively. Correlations with strength were as follows: knee extension, r = 0.74 (n = 60); elbow flexion, r = 0.77 (n = 61); and knee flexion, r = 0.74 (n = 58). The HFMSE differentiated patients by SMN2 copy number (P = .0007); bi-level positive airway pressure use, Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5545.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5544.phpThe genetic basis of oculopharyngeal muscular dystrophy (OPMD) is a short expansion of a polyalanine tract (normal allele: 10 alanines, mutant allele: 11-17 alanines) in the nuclear polyadenylate binding protein PABPN1 which is essential for controlling poly(A) tail length in messenger RNA. Mutant PABPN1 forms nuclear inclusions in OPMD muscle. To investigate the pathogenic role of mutant PABPN1 in vivo, a ligand-inducible transgenic mouse model was generated by using the mifepristone-inducible gene expression system. Induction of ubiquitous expression of mutant PABPN1 resulted in skeletal and cardiac myopathy. Histological changes of degenerative myopathy were preceded by nuclear inclusions of insoluble PABPN1. Downregulation of mutant PABPN1 expression attenuated the myopathy and reduced the nuclear burden of insoluble PABPN1. These results support association between mutant PABPN1 accumulation and degenerative myopathy in mice. Resolution of myopathy in mice suggests that the disease process in OPMD patients may be treatable.Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5544.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5543.phpSpinal muscular atrophy (SMA) is a neurodegenerative disease resulting from decreased levels of survival motor neuron 1 (SMN1) protein, which are linked to pathology at neuromuscular junctions (NMJs). There is currently no effective treatment for SMA. In this study, researchers at the University of Missouri (MU) found that the disruption in communication between nerves and muscles in mice causing degeneration of motor neurons is similar to the degeneration in movement that occurs in human beings suffering from SMA. This disruption causes motor neurons to stop working and muscle activity ceases. The way in which the nerve and muscle communicate becomes fragmented and muscles will not function correctly when the message sent by nerves to muscles is disrupted before it arrives at a nerve ending. As a result, muscles stop functioning and movement is impaired. Slowly the body loses its ability to walk, sit or stand. Ultimately, the ability to move at all is destroyed. The researchers suggest that this discovery could lead to the treatment of SMA as well as diseases involving motor neurons including ALS and the dysfunction of the synapses that occur in Duchenne Muscular Dystrophy.  Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5543.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5542.phpThis study demonstrates that a strong transcriptional enhancer within the D4Z4 repeat unit interacts with the Krüppel-like factor KLF15 and that the expression level of KLF15 regulates the activity of the D4Z4 enhancer which, in turns, induces expression of DUX4c in a KLF15-dependent manner. During muscle differentiation, increased expression of KLF15 activates the D4Z4 enhancer leading to activation of the promoter of the DUX4c gene. Furthermore, the results show that KLF15 is expressed at higher levels in muscle biopsies from FSHD patients compared to controls. Higher expression of KLF15 in muscles of FHSD patients could induce untimely over-expression of DUX4c with deleterious effects on muscle cell differentiation. The authors suggest that the KLF15-controlled D4Z4 enhancer may play a role in normal and pathological development of muscular cells. Thu, 20 Oct 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5542.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5505.phpThe Association Française contre les Myopathies launches its call for Proposals for 2012.This international call for proposals aims to support research which will:  increase our understandIng of the neuromuscular system encourage the development of therapies for neuromuscular diseases and rare genetic diseases improve care and quality of life of patients with neuromuscular diseases   The Calls for Proposals launched by AFM for 2012 are listed below:Call for Proposals AFM 2012 (PDF)2012 Instructions for Preparation of ApplicationsGrants :2012 Application for research project form2012 Application for research project renewal form2012 Application for trampoline grant formFellowships :2012 Application for PhD Fellowship form2012 Application for PhD Fellowship Renewal form2012 Application for Post doctoral Fellowship form2012 Application for Post doctoral Fellowship Renewal form Fri, 30 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5505.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5504.phpIn this study, a model of xenotransplantation in which human myoblasts were transplanted intramuscularly into immunodeficient Rag2(-/-)ăC(-/-) mice, were used to investigate the kinetics of proliferation and differentiation of the transplanted cells. After injection, most of the human myoblasts had already differentiated by day 5. This differentiation correlated with reduction in proliferation and limited migration of the donor cells within the regenerating muscle. These results suggest that the precocious differentiation, already detected at 3 days post-injection, is a limiting factor for both the migration from the injection site and the participation of the donor cells to muscle regeneration. In vivo proliferation of human myoblasts was stimulated by transplanting them in a serum-containing medium. Five days post-transplantation, the authors observed a delay of myogenic differentiation and an increase in cell numbers, which colonized a much larger area within the recipient's muscle. Importantly, these myoblasts maintained their ability to differentiate, as higher numbers of myofibres were observed 1 month post-engraftment, as compared to controls. Theoretically, these data suggest that in experimental myoblast transplantation, any intervention upon the donor cells and/or the recipient's microenvironment aimed at enhancing proliferation and migration should be done before differentiation of the implanted cells, e.g., day 3 post-engraftment.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5504.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5503.phpMutations in fukutin-related protein (FKRP) are responsible for a common group of muscular dystrophies ranging from adult onset limb girdle muscular dystrophies to severe congenital forms with associated structural brain involvement. The defining feature of this group of disorders is the hypoglycosylation of á-dystroglycan and its inability to effectively bind extracellular matrix ligands such as laminin á2. However, á-dystroglycan has the potential to interact with a number of laminin isoforms many of which are basement membrane/tissue specific and developmentally regulated. To further investigate this, laminin á-chain expression in the cerebral cortex and eye of the FKRP knock-down mouse (FKRP(KD)) was evaluated. These mice showed a marked disturbance in the deposition of laminin á-chains including á1, á2, á4, and á5, although only laminin á1- and ă1-chain mRNA expression was significantly upregulated relative to controls. Moreover, there was a diffuse pattern of laminin deposition below the pial surface, which correlated with an abrupt termination of many of the radial glial cells. This along with the pial basement membrane defects, contributed to the abnormal positioning of both early- and late-born neurons. Defects in the inner limiting membrane of the eye were associated with a reduction of laminin á1 demonstrating the involvement of the á-dystroglycan:laminin á1 axis in the disease process. These observations demonstrate for the first time that a reduction in Fkrp influences the ability of tissue-specific forms of á-dystroglycan to direct the deposition of several laminin isoforms in the formation of different basement membranes.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5503.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5502.phpThe natural progression of neuromuscular diseases results in inevitable musculotendinous contractures, most often in spite of early treatment. Surgery corrects this. The aim of this study was to evaluate the results of tendon surgery in these cases. Twenty children with muscular dystrophy underwent hip, knee and/or ankle surgery. Articular range of motion was evaluated preoperatively, 6 months after surgery, at 1 year and at the final follow-up 7.4 years later. Three children underwent surgery before they had lost their walking capacity, eight soon afterwards, and nine long afterwards. Surgery was bilateral in all cases: 38 hips, 12 knees and 36 ankles with 22 posterior tibial tendon transfers. Hip extension, which was limited by a 30° flexion contracture improved to 10° and stabilized at 14° at the final follow-up. Adduction which was -19° before surgery increased to 35° and had stabilized at 32° at the final follow-up. Knee flessum (38°) was only slightly improved (24°) and had regressed at the final follow-up. Equinus deformity (42°) was corrected to 9° of dorsal flexion with a slight loss (2°) at the final follow-up. Varus was improved from 11° to 6°, but this had regressed at 1 year (10°) and at the final follow-up (11°). Achilles tendon tenotomies resulted in 28° of dorsal flexion at 6months compared to 20° with lengthening. Correction of varus was better with posterior tibial tendon transfer at 6 months, 1 year and at the final follow-up (11° versus 5°). In the three patients who underwent surgery before losing their walking ability, one continued walking for 1 year and two for 6 months. None of the eight patients who underwent surgery soon after losing ambulation were able to regain walking. All patients were able to continue device assisted upright positioning for a mean 3 years. Hip and ankle surgery can release contractures. In the knees, surgery should be restricted to cases with knee flessum greater than 30°. The best results are obtained with extensive m. tensor fascia lata tenectomy and posterior tibial tendon transfer. Achilles tendon tenotomy results in better recovery of dorsal flexion. Surgery is indicated when contractures are severe and the patient is no longer able to walk. The aim should not be to continue walking but to release contractures, so that the patient can continue assisted upright positioning as long as possible. Especially in cases of asymmetric contractures, surgery can help slow the progression of scoliosis.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5502.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5501.phpMyostatin is a negative regulator of skeletal muscle growth and in fact acts as a potent inducer of "cachectic-like" muscle wasting in mice. The mechanism of action of myostatin in promoting muscle wasting has been predominantly studied in murine models. Despite numerous reports linking elevated levels of myostatin to human skeletal muscle wasting conditions, little is currently known about the signalling mechanism(s) through which myostatin promotes human skeletal muscle wasting. This study describes in further detail the mechanisms behind myostatin regulation of human skeletal muscle wasting using an in vitro human primary myotube atrophy model. Treatment of human myotube populations with myostatin promoted dramatic myotubular atrophy. Mechanistically, myostatin-induced myotube atrophy resulted in reduced p-AKT concomitant with the accumulation of active dephosphorylated FOXO1 and FOXO3. Moreover, addition of myostatin results in enhanced activation of Atrogin-1 and MURF1 and reduced expression of both Myosin Light Chain (MYL) and Myosin Heavy Chain (MYH). In addition, myostatin-induced loss of MYL and MYH proteins is dependent on the activity of the proteasome and mediated via SMAD3-dependent regulation of FOXO1 and Atrogin-1. Therefore, these data suggest that the mechanism through which myostatin promotes muscle wasting is very well conserved between species, and that myostatin-induced human myotube atrophy is mediated through inhibition of IGF/PI3-K/AKT signalling and enhanced activation of the ubiquitin-proteasome pathway and elevated protein degradation.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5501.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5500.phpPharmaceutical companies Genzyme and PTC Therapeutics have restructured their collaboration for the development of the drug ataluren for Duchenne muscular dystrophy. Ataluren is an oral drug that has been developed in the US by PTC Therapeutics to overcome a nonsense mutation. About 10-15% of boys with Duchenne muscular dystrophy have this type of mutation. In very rare cases, nonsense mutations occurring in certain positions in the dystrophin gene can also cause the milder symptoms of Becker muscular dystrophy. Under the original agreement, PTC Therapeutics held the commercial rights for ataluren in the US and Canada, while Genzyme held commercial rights in all other countries. Under the restructured agreement, PTC has regained worldwide rights to ataluren and Genzyme will retain an option to commercialise ataluren for conditions other than Duchenne/Becker muscular dystrophy outside the US and Canada. Genzyme announced in May that they were planning a follow-on clinical study of ataluren for Duchenne muscular dystrophy patients who previously participated in the clinical trials in the UK, Europe, Israel and Australia. This new trial will allow for the collection of additional information on ataluren, since the results of the previous trial were inconclusive. It will also provide access to ataluren to all patients who have been involved in earlier clinical trials. The follow-on clinical trial is due to start in December 2011. Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5500.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5499.phpBy using the French dystrophinopathy database, this study aimed to clarify the clinical heterogeneity in Duchenne muscular dystrophy (DMD). The database provided clinical, histochemical and molecular data of 278 DMD patients (mean longitudinal follow-up: 14.2 years). Diagnosis was based on mutation identification in the DMD gene. Three groups were defined according to the age at ambulation loss: before 8 years (group A); between 8 and 11 years (group B); between 11 and 16 years (group C). Motor and respiratory declines were statistically different between the three groups, as opposed to heart involvement. When acquired, running ability was lost at the mean age of 5.41 (group A), 7.11 (group B), 9.19 (group C) years; climbing stairs ability at 6.24 (group A), 7.99 (group B), 10,42 (group C) years, and ambulation at 7.10 (group A), 9.25 (group B), 12.01 (group C) years. Pulmonary growth stopped at 10.26 (group A), 12.45 (group B), 14.58 (group C) years. Then, forced vital capacity decreased at the rate of 8.83 (group A), 7.52 (group B), 6.03 (group C) percent per year. Phenotypic variability did not rely on specific mutational spectrum. Beside the most common form of DMD (group B), this study provides a detailed description on two extreme clinical subgroups: a severe one (group A) characterized by early severe motor and respiratory decline and a milder subgroup (group C). Compared to group B or C, four to six times fewer patients from group A are needed to detect the same decrease in disease progression in a clinical trial.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5499.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5498.phpDuchenne muscular dystrophy (DMD) is a genetic progressive muscle disease resulting from the lack of dystrophin. To date, there is no effective treatment for this disease. Adult stem cell populations have given new impetus to cell-based therapy of neuromuscular diseases. One of them, muscle-derived stem cells, isolated based on delayed adhesion properties, contributes to injured muscle repair. However, these data were collected in dystrophic mice that exhibit a relatively mild tissue phenotype and clinical features of DMD patients. In this study, the authors characterized canine delayed adherent stem cells and investigated the efficacy of their systemic delivery in the clinically relevant DMD animal model to assess potential therapeutic application in humans. Delayed adherent stem cells, termed MuStem cells (muscle stem cells), were isolated from healthy dog muscle using a preplating technique. In vitro, MuStem cells displayed a large expansion capacity, an ability to proliferate in suspension, and a multilineage differentiation potential. Phenotypically, they corresponded to early myogenic progenitors and uncommitted cells. When injected in immunosuppressed dystrophic dogs, they contributed to myofiber regeneration, satellite cell replenishment, and dystrophin expression. Importantly, their systemic delivery resulted in long-term dystrophin expression, muscle damage course limitation with an increased regeneration activity and an interstitial expansion restriction, and persisting stabilization of the dog's clinical status. These results demonstrate that MuStem cells provide an attractive therapeutic avenue for DMD patients.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5498.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5497.phpCongenital muscular dystrophy caused by laminin á2 chain deficiency (also known as MDC1A) is a severe and incapacitating disease, characterized by massive muscle wasting. The ubiquitin-proteasome system plays a major role in muscle wasting and we recently demonstrated that increased proteasomal activity is a feature of MDC1A. The autophagy-lysosome pathway is the other major system involved in degradation of proteins and organelles within the muscle cell. However, it remains to be determined if the autophagy-lysosome pathway is dysregulated in muscular dystrophies including MDC1A. Using the dy(3K)/dy(3K) mouse model of laminin á2 chain deficiency and MDC1A patient muscle, it was demonstrated that expression of autophagy-related genes is upregulated in laminin á2 chain deficient muscle. Furthermore, autophagy inhibition significantly improves the dystrophic dy(3K)/dy(3K) phenotype. Particularly, systemic injection of 3-methyladenine (3-MA) reduces muscle fibrosis, atrophy, apoptosis and increases muscle regeneration and muscle mass. Importantly, lifespan and locomotive behaviour were also greatly improved. These findings indicate that enhanced autophagic activity is pathogenic and that autophagy inhibition holds a promising therapeutic potential in the treatment of MDC1A.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5497.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5496.phpMyotonic dystrophy type 2 (DM2) is a recently discovered adult muscular dystrophy. Similar to DM1, this disease causes progressive debilitating weakness, clinical myotonia, and early cataracts and is thought to cause widespread physiologic dysfunction of multiple organ systems. This study aimed to analyse and compile the laboratory abnormalities of 83 adults with genetically confirmed or clinically probable DM2; of these patients, 49 had documented baseline laboratory screening. Baseline DM2 laboratory data were compiled representing 68 different types of laboratory tests and 1442 total studies. The main outcome was the individual frequencies of abnormal laboratory values in the population with DM2 studied. Of the 1442 studies, results for 359 (24.9%) were outside of their standard reference ranges. Of the 68 types of laboratory tests studied, 43 had values from 15 or more different patients with DM2. The relative frequency of an abnormally elevated laboratory value was greater than 50% in several tests, including the levels of creatine kinase, total cholesterol, lactate dehydrogenase, and alanine aminotransferase. In addition, serum levels of IgG were low in 75% of all patients with DM2 tested, and absolute lymphocyte counts were low in 54% of all patients with DM2 tested. There is a high frequency of laboratory abnormalities in patients with DM2. These abnormalities provide insight into the widespread pathologic manifestations of DM2 and may form a basis for clinical monitoring and disease screening.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5496.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5495.phpScientists have made an exciting breakthrough in unravelling the genetic basis of 2 debilitating neurodegenerative disorders: amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Two independent studies have identified a new human genetic mutation as the most common cause of ALS and FTD identified to date. This mutation explains at least a third of all familial cases of ALS and FTD within the European population. The research provides key insight into ALS and FTD and may pave the way for development of therapeutic strategies for these currently incurable diseases. About 10% of ALS cases and about 50% of FTD cases are thought to be inherited, and, although multiple genes have been linked with the disorders, much of the genetic risk has remained unexplained. Recent research has linked a region on chromosome 9 (9p21) with both ALS and FTD. Dr. Traynor's group from the National Institutes of Health, Maryland, performed an exhaustive next generation genetic analysis of this region in patients with 9p21-associated ALS or FTD, including the group of Finnish ALS patients that had previously been used to identify the association with 9p21. A second research group, led by Rosa Rademakers, Mayo Clinic, Florida, performed a similar analysis using a large family with ALS and FTD linked to chromosome 9p21. Both groups discovered a “repeat expansion” within the non-coding region of C9ORF72, a gene whose function is not known. This mutation argues that both ALS and FTD are diseases caused by defects in RNA metabolism. This idea is in line with other recent work in ALS, FTD and neurodegenerative diseases more broadly stressing RNA-driven disease pathology. The researchers investigated clinical and pathological characteristics associated with the mutation. Taken together, the findings of both studies suggest that the repeat expansion in C9ORF72 is a major cause of an unprecedented proportion of both sporadic and familial FTD and ALS cases. The mutation explains nearly half of all cases in Finland alone and at least a third of all familial FTD and ALS cases in Europeans. Importantly, the mutation was also associated with a number of non-inherited cases of ALS and FTD. With this discovery, nearly all cases of familial ALS disease in Finland, which has the highest incidence of ALS in the world, can be explained. In the longer term, the identification of the genetic lesion underlying chromosome 9p21-linked ALS and FTD, together with the observed high frequency in these patient populations, makes it an ideal target for drug development aimed at amelioration of the disease process.Sun, 25 Sep 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5495.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5471.phpAge-related loss of muscle mass and force (sarcopenia) contributes to disability and increased mortality. Ryanodine receptor 1 (RyR1) is the skeletal muscle sarcoplasmic reticulum calcium release channel required for muscle contraction. RyR1 from aged (24 months) rodents was oxidized, cysteine-nitrosylated, and depleted of the channel-stabilizing subunit calstabin1, compared to RyR1 from younger (3-6 months) adults. This RyR1 channel complex remodeling resulted in "leaky" channels with increased open probability, leading to intracellular calcium leak in skeletal muscle. Similarly, 6-month-old mice harboring leaky RyR1-S2844D mutant channels exhibited skeletal muscle defects comparable to 24-month-old wild-type mice. Treating aged mice with S107 stabilized binding of calstabin1 to RyR1, reduced intracellular calcium leak, decreased reactive oxygen species (ROS), and enhanced tetanic Ca(2+) release, muscle-specific force, and exercise capacity. Taken together, these data indicate that leaky RyR1 contributes to age-related loss of muscle function.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5471.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5470.phpBackground: Shared medical appointments are a series of one-to-one doctor-patient contacts, in presence of a group of 6-10 fellow patients. This group visits substitute the annual control visits of patients with the neurologist. The same items attended to in a one-to-one appointment are addressed. The possible advantages of a shared medical appointment could be an added value to the present management of neuromuscular patients. The currently problem-focused one-to-one out-patient visits often leave little time for the patient's psychosocial needs, patient education, and patient empowerment. Methods/design: A randomized, prospective controlled study (RCT) with a follow up of 6 months will be conducted to evaluate the clinical and cost-effectiveness of shared medical appointments compared to usual care for 300 neuromuscular patients and their partners at the Radboud University Nijmegen Medical Center. Every included patient will be randomly allocated to one of the two study arms. This study has been reviewed and approved by the medical ethics committee of the region Arnhem-Nijmegen, the Netherlands. The primary outcome measure is quality of life as measured by the EQ-5D, SF-36 and the Individualized neuromuscular Quality of Life Questionnaire. The primary analysis will be an intention-to-treat analysis on the area under the curve of the quality of life scores. A linear mixed model will be used with random factor group and fixed factors treatment, baseline score and type of neuromuscular disease. For the economic evaluation an incremental cost-effectiveness analysis will be conducted from a societal perspective, relating differences in costs to difference in health outcome. Results are expected in 2012. Discussion: This study will be the first randomized controlled trial which evaluates the effect of shared medical appointments versus usual care for neuromuscular patients. This will enable to determine if there is additional value of shared medical appointments to the current therapeutical spectrum. When this study shows that group visits produce the alleged benefits, this may help to increase the acceptance of this innovative and creative way of using one of the most precious resources in health care more efficiently: time. Trial registration: DutchTrial Register www.trialregister.nl NTR1412.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5470.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5469.phpThe nuclear lamina provides structural support to the nucleus and has a central role in nuclear organization and gene regulation. Defects in its constituents, the lamins, lead to a class of genetic diseases collectively referred to as laminopathies. Using live cell imaging, we observed the occurrence of intermittent, non-lethal ruptures of the nuclear envelope in dermal fibroblast cultures of patients with different mutations of Lamin A/C. These ruptures, which were absent in normal fibroblasts, could be mimicked by selective knockdown as well as knockout of LMNA and were accompanied by the loss of cellular compartmentalization. This was demonstrated by the influx of cytoplasmic transcription factor RelA and regulatory protein Cyclin B1 into the nucleus, and efflux of nuclear transcription factor OCT1 and nuclear PML-containing structures to the cytoplasm. While recovery of EYFP-tagged nuclear localisation signal in the nucleus demonstrated restoration of nuclear membrane integrity, part of the mobile PML structures became permanently translocated to the cytoplasm. These satellite PML structures were devoid of the typical PML body components such as DAXX, SP100 or SUMO1. Our data suggest that nuclear rupture and loss of compartmentalization may add to cellular dysfunction and disease development in various laminopathies.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5469.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5468.phpIn contrast to conventional gene therapy vectors, human artificial chromosomes (HACs) are episomal vectors that can carry large regions of the genome containing regulatory elements. So far, HACs have not been used as vectors in gene therapy for treating genetic disorders. Here, we report the amelioration of the dystrophic phenotype in the mdx mouse model of Duchenne muscular dystrophy (DMD) using a combination of HAC-mediated gene replacement and transplantation with blood vessel-associated stem cells (mesoangioblasts). We first genetically corrected mesoangioblasts from dystrophic mdx mice with a HAC vector containing the entire (2.4 Mb) human dystrophin genetic locus. Genetically corrected mesoangioblasts engrafted robustly and gave rise to many dystrophin-positive muscle fibers and muscle satellite cells in dystrophic mice, leading to morphological and functional amelioration of the phenotype that lasted for up to 8 months after transplantation. Thus, HAC-mediated gene transfer shows efficacy in a preclinical model of DMD and offers potential for future clinical translation.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5468.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5467.phpMyasthenia gravis (MG) is an autoimmune disorder characterized by a defect in synaptic transmission at the neuromuscular junction causing fluctuating muscle weakness with a decremental response to repetitive nerve stimulation or altered jitter in single-fiber electromyography (EMG). Approximately 80% of all myasthenia gravis patients have autoantibodies against the nicotinic acetylcholine receptor in their serum. Autoantibodies against the tyrosine kinase muscle-specific kinase (MuSK) are responsible for 5-10% of all myasthenia gravis cases. The autoimmune target in the remaining cases is unknown. Recently, low-density lipoprotein receptor-related protein 4 (LRP4) has been identified as the agrin receptor. LRP4 interacts with agrin, and the binding of agrin activates MuSK, which leads to the formation of most if not all postsynaptic specializations, including aggregates containing acetylcholine receptors (AChRs) in the junctional plasma membrane. In the present study we tested if autoantibodies against LRP4 are detectable in patients with myasthenia gravis. To this end we analyzed 13 sera from patients with generalized myasthenia gravis but without antibodies against AChR or MuSK. The results showed that 12 out of 13 antisera from double-seronegative MG patients bound to proteins concentrated at the neuromuscular junction of adult mouse skeletal muscle and that approximately 50% of the tested sera specifically bound to HEK293 cells transfected with human LRP4. Moreover, 4 out of these 13 sera inhibited agrin-induced aggregation of AChRs in cultured myotubes by more than 50%, suggesting a pathogenic role regarding the dysfunction of the neuromuscular endplate. These results indicate that LRP4 is a novel target for autoantibodies and is a diagnostic marker in seronegative MG patients.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5467.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5466.phpCharcot-Marie-Tooth disease is characterized by length-dependent axonal degeneration with distal sensory loss and weakness, deep-tendon-reflex abnormalities, and skeletal deformities. It is caused by mutations in more than 40 genes. We investigated a four-generation family with 23 members affected by the axonal form (type 2), for which the common causes had been excluded by Sanger sequencing. Exome sequencing of three affected individuals separated by eight meioses identified a single shared novel heterozygous variant, c.917A>G, in DYNC1H1, which encodes the cytoplasmic dynein heavy chain 1 (here, novel refers to a variant that has not been seen in dbSNP131or the August 2010 release of the 1000 Genomes project). Testing of six additional affected family members showed cosegregation and a maximum LOD score of 3.6. The shared DYNC1H1 gene variant is a missense substitution, p.His306Arg, at a highly conserved residue within the homodimerization domain. Three mouse models with different mutations within this domain have previously been reported with age-related progressive loss of muscle bulk and locomotor ability. Cytoplasmic dynein is a large multisubunit motor protein complex and has a key role in retrograde axonal transport in neurons. Our results highlight the importance of dynein and retrograde axonal transport in neuronal function in humans.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5466.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5465.phpTreatment of dominantly inherited muscle disorders remains a difficult task considering the need to eliminate the pathogenic gene product in a body-wide fashion. We show here that it is possible to reverse dominant muscle disease in a mouse model of facioscapulohumeral muscular dystrophy (FSHD). FSHD is a common form of muscular dystrophy associated with a complex cascade of epigenetic events following reduction in copy number of D4Z4 macrosatellite repeats located on chromosome 4q35. Several 4q35 genes have been examined for their role in disease, including FRG1. Overexpression of FRG1 causes features related to FSHD in transgenic mice and the FRG1 mouse is currently the only available mouse model of FSHD. Here we show that systemic delivery of RNA interference expression cassettes in the FRG1 mouse, after the onset of disease, led to a dose-dependent long-term FRG1 knockdown without signs of toxicity. Histological features including centrally nucleated fibers, fiber size reduction, fibrosis, adipocyte accumulation, and inflammation were all significantly improved. FRG1 mRNA knockdown resulted in a dramatic restoration of muscle function. Through RNA interference (RNAi) expression cassette redesign, our method is amenable to targeting any pathogenic gene offering a viable option for long-term, body-wide treatment of dominant muscle disease in humans.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5465.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5464.phpAutoantibodies to signal recognition particle have been associated with juvenile and adult-onset necrotizing myopathy. However, only a few teenage patients with anti-signal recognition particle myopathy have been reported, and to date, to our knowledge, no patient younger than 10 years has been documented. We describe 2 Japanese girls with anti-signal recognition particle myopathy who developed symptoms from the ages of 5 and 9 years, respectively. Both patients had progressive muscle weakness and atrophy without myalgia. Facioscapulohumeral muscular dystrophy was initially suspected because of asymmetric shoulder girdle muscle involvement in one patient, and limb girdle muscular dystrophy due to proximal limb muscle weakness in the other. There were no extramuscular manifestations, including fever or arthritis. Serum creatine kinase levels were elevated to 2,467-4,629 IU/L. Results of muscle biopsy revealed necrotizing myopathy with minimal to mild endomysial fibrosis but without inflammatory infiltrates. Immunosuppressive agents were not effective for muscle weakness, resulting in marked disability. Anti-signal recognition particle myopathy can occur in the first decade of life and should be included in the differential diagnosis for children with progressive limb girdle muscle weakness and high creatine kinase levels.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5464.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5463.phpProtein O-mannosyltransferase 1 (POMT1) and its homolog, POMT2, are responsible for the catalysis of the first step in O-mannosyl glycan synthesis. Mutations in their genes are associated with a type of congenital muscular dystrophy called Walker-Warburg syndrome. Arg(64), Glu(78) and Arg(138) in the N-terminus region of ScPmt1p, a POMT homolog in Saccharomyces cerevisiae, are important for transferase activity. Arg(138) is also essential for complex formation with ScPmt2p. Here we examined the effects of replacing the corresponding residues in human POMT1 and POMT2 with Ala on complex formation and enzymatic activity. The human POMT1 mutants lost almost all transferase activity while the POMT2 mutants retained enzymatic activity. Neither mutant lost its ability to form complexes with the native counter component. These results indicate that ScPmtps and human POMTs have different mechanisms of complex formation. They also suggest that human POMT1 and POMT2 have discrete functions since the effect of amino acid substitutions on enzymatic activity are different.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5463.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5462.phpBackground: Nearly universal cardiomyopathy in Duchenne muscular dystrophy (DMD) contributes to heart failure and death. Because DMD patients show myocardial fibrosis well before functional impairment, we postulated that earlier treatment using drugs with antifibrotic effect may be beneficial. Methods and Results: Three groups of 10 utrn(+/-);mdx, or "het" mice, deficient for dystrophin and haploinsufficient for utrophin with skeletal myopathy and cardiomyopathy that closely mimics clinical DMD were studied. One het group received spironolactone and lisinopril starting at 8 weeks of life (het-treated-8); a second received the same starting at 4 weeks of life (het-treated-4), and the third het group was untreated. At 20 weeks, all mice had normal ejection fractions though circumferential strain rate was abnormal (-0.21±0.08) in untreated hets. This improved to -0.40±0.07 in het-treated-8 mice (P=0.003) and further improved to -0.56±0.10 in het-treated-4 mice (P=0.014 for het-treated-4 versus het-treated-8). Treated mice showed less cardiomyocyte damage, with a 44% reduction in intracardiomyocyte serum immunoglobulin G localization in het-treated-8 mice (P<0.0001) and a further 53% reduction in het-treated-4 mice (P=0.0003 versus het-treated-8); matrix metalloproteinases were similarly reduced. Cardiac, limb, and diaphragm function by ex vivo muscle testing remained at 80% of normal with early treatment compared to a decline to 40% of normal skeletal muscle function without treatment. Conclusions: These findings offer clinically available medications with proven antifibrotic effect as a new therapeutic strategy in DMD. Early initiation greatly attenuated myocardial disease and, for the first time with these drugs, improved skeletal myopathy. Thus, early initiation of such agents warrants further clinical evaluation to maintain ambulatory, respiratory, and cardiac function for patients with DMD and related myopathies.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5462.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5461.phpBackground: We report clinical safety and biochemical efficacy from a dose-ranging study of intravenously administered AVI-4658 phosphorodiamidate morpholino oligomer (PMO) in patients with Duchenne muscular dystrophy. Method: We undertook an open-label, phase 2, dose-escalation study (0.5, 1.0, 2.0, 4.0, 10.0, and 20.0 mg/kg bodyweight) in ambulant patients with Duchenne muscular dystrophy aged 5-15 years with amenable deletions in DMD. Participants had a muscle biopsy before starting treatment and after 12 weekly intravenous infusions of AVI-4658. The primary study objective was to assess safety and tolerability of AVI-4658. The secondary objectives were pharmacokinetic properties and the ability of AVI-4658 to induce exon 51 skipping and dystrophin restoration by RT-PCR, immunohistochemistry, and immunoblotting. The study is registered, number NCT00844597. Findings: 19 patients took part in the study. AVI-4658 was well tolerated with no drug-related serious adverse events. AVI-4658 induced exon 51 skipping in all cohorts and new dystrophin protein expression in a significant dose-dependent (p=0.0203), but variable, manner in boys from cohort 3 (dose 2 mg/kg) onwards. Seven patients responded to treatment, in whom mean dystrophin fluorescence intensity increased from 8.9% (95% CI 7.1-10.6) to 16.4% (10.8-22.0) of normal control after treatment (p=0.0287). The three patients with the greatest responses to treatment had 21%, 15%, and 55% dystrophin-positive fibres after treatment and these findings were confirmed with western blot, which showed an increase after treatment of protein levels from 2% to 18%, from 0.9% to 17%, and from 0% to 7.7% of normal muscle, respectively. The dystrophin-associated proteins α-sarcoglycan and neuronal nitric oxide synthase were also restored at the sarcolemma. Analysis of the inflammatory infiltrate indicated a reduction of cytotoxic T cells in the post-treatment muscle biopsies in the two high-dose cohorts. Interpretation: The safety and biochemical efficacy that we present show the potential of AVI-4658 to become a disease-modifying drug for Duchenne muscular dystrophy.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5461.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5460.phpMutations in the epsilon subunit of the acetylcholine receptor (AChR) are a common cause of congenital myasthenic syndrome (CMS). Patients are usually treated with acetylcholinesterase inhibitors and 3,4-diaminopyridine with modest clinical benefit. We report 2 patients with CMS due to mutations in the AChR epsilon subunit. The first patient carries two heterozygous frameshift mutations, ?127ins5 and ?1293insG. The second patient is homozygous for the ?C142Y mutation that curtails AChR expression to 22% of wild-type in HEK cells. Treatment with pyridostigmine and 3,4-diaminopyridine had a limited beneficial effect in the first patient, and the second patient became wheelchair-bound during therapy. The additional use of albuterol produced dramatic improvement in strength and in activities of daily living in both patients. The efficacy and safety of albuterol in patients who harbor identified low-expressor or null mutations in the epsilon or other subunits of AChR merits a well-designed clinical trial. Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5460.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5459.phpOsteoporosis is a common complication in children with motor impairments. They have a higher risk of fractures (20% during their lifetime) mostly at femoral level. Furthermore, these children have pain yet no clear relation has been established between osteoporosis and pain. The efficacy of bisphosphonates has been validated in adults and for children with osteogenesis imperfecta (OI). However, its use in children with motor impairments has not yet been validated. Patients and Methods: Retrospective study on the medical charts of children presenting neurological diseases and motor impairments associated to secondary symptomatic osteoporosis. These children underwent treatment with Pamidronate(®) intravenous infusions (I.V.) in Lyon and Valence between 2002 and 2008. Data were collected on pain control, incidence and frequency of fractures and bone mass density (BMD). Data on adverse events were also collected to evaluate treatment's tolerance. Results: Twelve children's charts were studied for a total of 50 Pamidronate(®) I.V. infusions. Regarding treatment's efficacy, we observed a clear decrease and even total relief of the pain with improvement reported after 98% of perfusions. Regarding BMD, there was a real improvement after the treatment (e.g., lumbar BMD measures, -46.5% before treatment and -27% after treatment). The adverse events, flu-like syndrome, muscle pain and asymptomatic hypocalcemia, were minor and quickly reversible. Conclusion: It seems quite essential to screen for osteoporosis-related pain in these children and treat them quickly to avoid a negative impact on their quality of life. Treatment with I.V. bisphosphonates has shown its relevance, yet practical modalities still need to be defined. It would be interesting but quite difficult to implement, in light of the positive effect of this study, a prospective, randomized, controlled, double-blind vs. placebo study on a large enough sample of patients.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5459.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5458.phpCharcot-Marie-Tooth disease (CMT) is the most common inherited disorder of the peripheral nervous system. Mutations in the 27-kDa small heat-shock protein gene (HSPB1) cause axonal CMT or distal hereditary motor neuropathy (distal HMN). We developed and characterized transgenic mice expressing two different HSPB1 mutations (S135F and P182L) in neurons only. These mice showed all features of CMT or distal HMN dependent on the mutation. Expression of mutant HSPB1 decreased acetylated á-tubulin abundance and induced severe axonal transport deficits. An increase of á-tubulin acetylation induced by pharmacological inhibition of histone deacetylase 6 (HDAC6) corrected the axonal transport defects caused by HSPB1 mutations and rescued the CMT phenotype of symptomatic mutant HSPB1 mice. Our findings demonstrate the pathogenic role of á-tubulin deacetylation in mutant HSPB1-induced neuropathies and offer perspectives for using HDAC6 inhibitors as a therapeutic strategy for hereditary axonopathies.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5458.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5457.phpWe evaluated safety and feasibility of the transvenous limb perfusion gene delivery method in muscular dystrophy. A dose escalation study of single limb perfusion with 0.9% saline starting with 5% of limb volume was carried out in adults with muscular dystrophies under intravenous analgesia/anesthesia. Cardiac, vascular, renal, muscle, and nerve functions were monitored. A tourniquet was placed above the knee with inflated pressure of 310 mm Hg. Infusion was carried out with a clinically approved infuser via an intravenous catheter inserted in the saphenous vein with a goal infusion rate of 80 ml/minute. Infusion volume was escalated stepwise to 20% limb volume in seven subjects. No subject complained of any post procedure pain other than due to needle punctures. Safety warning boundaries were exceeded only for transient depression of limb tissue oximetry and transient elevation of muscle compartment pressures; these were not associated with nerve, muscle, or vascular damage. Muscle magnetic resonant imaging (MRI) demonstrated fluid accumulation in muscles of the perfused lower extremity. High-pressure retrograde transvenous limb perfusion with saline up to 20% of limb volume at above infusion parameters is safe and feasible in adult human muscular dystrophy. This study will serve as a basis for future gene transfer clinical trials.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5457.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5456.phpConstitutional laminopathies, such as the Dunnigan familial partial lipodystrophy, are severe diseases caused by mutations in A-type lamins and share several features with metabolic syndrome (MS). In this study, we hypothesized that MS may be, in some cases, a mild form of laminopathies and use the abnormal cell nucleus phenotype observed in these diseases as a primary screening test in patients suffering from common MS. Nuclear shape and lamin A nucleoplasmic distribution abnormalities were systematically searched in lymphoblastoid cells of 87 consecutive patients with MS. In parallel, five genes encoding either the A-type lamins or the enzymes of the lamin A maturation pathway were systematically sequenced (LMNA, ZMPSTE24, ICMT, FNTA and FNTB). We identified 10 MS patients presenting abnormal nuclear shape and disturbed lamin A/C nuclear distribution. These patients were not clinically different from those without nuclear abnormalities except that they were younger, and had higher triglyceridemia and SGPT levels. Three of them carry a heterozygous mutation in LMNA or in ZMPSTE24, a gene encoding one of the lamin A processing enzymes. All three mutations are novel missense mutations predicted to be damaging. Both lymphoblastoid cells and skin fibroblasts from the patient carrying the mutation in ZMPSTE24, showed accumulation of lamin A precursor, indicating an alteration of the lamin A processing, confirmed by functional study. Together, these results show for the first time, that a significant proportion of MS patients exhibits laminopathies and suggest that systematic investigation of lamin A and its partners should be performed at the diagnosis of this syndrome.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5456.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5455.phpDuchenne muscular dystrophy (DMD) is a degenerative disorder affecting skeletal and cardiac muscle for which there is no effective therapy. Angiotension receptor blockade (ARB) has excellent therapeutic potential in DMD based on recent data demonstrating attenuation of skeletal muscle disease progression during 6-9 months of therapy in the mdx mouse model of DMD. Since cardiac-related death is major cause of mortality in DMD, it is important to evaluate the effect of any novel treatment on the heart. Therefore, we evaluated the long-term impact of ARB on both the skeletal muscle and cardiac phenotype of the mdx mouse. Mdx mice received either losartan (0.6 g/L) (n?=?8) or standard drinking water (n?=?9) for two years, after which echocardiography was performed to assess cardiac function. Skeletal muscle weight, morphology, and function were assessed. Fibrosis was evaluated in the diaphragm and heart by Trichrome stain and by determination of tissue hydroxyproline content. By the study endpoint, 88% of treated mice were alive compared to only 44% of untreated (p?=?0.05). No difference in skeletal muscle morphology, function, or fibrosis was noted in losartan-treated animals. Cardiac function was significantly preserved with losartan treatment, with a trend towards reduction in cardiac fibrosis. We saw no impact on the skeletal muscle disease progression, suggesting that other pathways that trigger fibrosis dominate over angiotensin II in skeletal muscle long term, unlike the situation in the heart. Our study suggests that ARB may be an important prophylactic treatment for DMD-associated cardiomyopathy, but will not impact skeletal muscle disease.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5455.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5454.phpBackground: Multiple lines of evidence have suggested that valproic acid (VPA) might benefit patients with spinal muscular atrophy (SMA). The SMA CARNIVAL TRIAL was a two part prospective trial to evaluate oral VPA and l-carnitine in SMA children. Part 1 targeted non-ambulatory children ages 2-8 in a 12 month cross over design. We report here Part 2, a twelve month prospective, open-label trial of VPA and L-carnitine in ambulatory SMA children. Methods: This study involved 33 genetically proven type 3 SMA subjects ages 3-17 years. Subjects underwent two baseline assessments over 4-6 weeks and then were placed on VPA and L-carnitine for 12 months. Assessments were performed at baseline, 3, 6 and 12 months. Primary outcomes included safety, adverse events and the change at 6 and 12 months in motor function assessed using the Modified Hammersmith Functional Motor Scale Extend (MHFMS-Extend), timed motor tests and fine motor modules. Secondary outcomes included changes in ulnar compound muscle action potential amplitudes (CMAP), handheld dynamometry, pulmonary function, and Pediatric Quality of Life Inventory scores. Results: Twenty-eight subjects completed the study. VPA and carnitine were generally well tolerated. Although adverse events occurred in 85% of subjects, they were usually mild and transient. Weight gain of 20% above body weight occurred in 17% of subjects. There was no significant change in any primary outcome at six or 12 months. Some pulmonary function measures showed improvement at one year as expected with normal growth. CMAP significantly improved suggesting a modest biologic effect not clinically meaningful. Conclusions: This study, coupled with the CARNIVAL Part 1 study, indicate that VPA is not effective in improving strength or function in SMA children. The outcomes used in this study are feasible and reliable, and can be employed in future trials in SMA. TRIAL REGSITRATION: Clinicaltrials.gov NCT00227266.Wed, 31 Aug 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5454.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5400.phpInduced splice modulation of pre-mRNAs shows promise to correct aberrant disease transcripts and restore functional protein and thus has therapeutic potential. Duchenne muscular dystrophy (DMD) results from mutations that disrupt the DMD gene open reading frame causing an absence of dystrophin protein. Antisense oligonucleotide (AO)-mediated exon skipping has been shown to restore functional dystrophin in mdx mice and DMD patients treated intramuscularly in two recent phase 1 clinical trials. Critical to the therapeutic success of AO-based treatment will be the ability to deliver AOs systemically to all affected tissues including the heart. Here, we report identification of a series of transduction peptides (Pip5) as AO conjugates for enhanced systemic and particularly cardiac delivery. One of the lead peptide-AO conjugates, Pip5e-AO, showed highly efficient exon skipping and dystrophin production in mdx mice with complete correction of the aberrant DMD transcript in heart, leading to >50% of the normal level of dystrophin in heart. Mechanistic studies indicated that the enhanced activity of Pip5e-phosphorodiamidate morpholino (PMO) is partly explained by more efficient nuclear delivery. Pip5 series derivatives therefore have significant potential for advancing the development of exon skipping therapies for DMD and may have application for enhanced cardiac delivery of other biotherapeutics.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5400.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5399.phpOBJECTIVES: Cardiac involvement has been reported in carriers of dystrophin mutations giving rise to Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). The progress of these abnormalities during long-term follow-up is unknown. We describe the long-term follow-up of dilated cardiomyopathy (DCM) in DMD/BMD carriers.METHODS: A long-term follow-up study was performed among Dutch DMD/BMD carriers first analyzed in 1995. A cardiac history was taken, and all carriers were assigned a functional score to assess skeletal muscle involvement. Electrocardiography and M-mode and 2-D echocardiography were performed. DCM was defined as an enlarged left ventricle with a global left ventricle dysfunction or fractional shortening less than 28%. Slow vital capacity of the lung was measured by a hand-held spirometer.RESULTS: Ninety-nine carriers were monitored with a median follow-up of 9 years (range 7.0-10.6 years). Eleven carriers with DCM (10 DMD, 1 BMD) were identified. Nine of them developed DCM in the follow-up period. One of the patients with DCM reported in the 1995 study died of cardiac failure at age 57 years. DCM was more frequently found in carriers who were functionally symptomatic.CONCLUSION: Cardiac abnormalities in DMD/BMD carriers are progressive, as in patients with DMD/BMD.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5399.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5398.phpThe important role of a molecule involved in skeletal muscle development has been discovered by researchers. The finding could have implications in the future for maintenance of healthy muscle or muscle regeneration in certain diseases, for example cancer and neuromuscular conditions such as muscular dystrophy. The complexity and significance of microRNA molecules has only recently been recognized and they have been implicated in many biological processes, including disease. Until now nothing was known about their role in the development of skeletal muscle, which is pivotal for movement and supports healthy ageing. The researchers showed that a particular microRNA, called miR-206, is crucial for normal muscle development in the embryo. MiR-206 switches off a gene called Pax3, this in turn allows early stage muscle cells to become more specialised contractile cells needed for muscle to function. The researchers suggest that this regulation is also important in adult muscle stem cells, which differentiate in response to muscle injury or exercise. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5398.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5397.phpCharcot-Marie-Tooth disease is a genetically heterogeneous group of motor and sensory neuropathies associated with mutations in more than 30 genes. Charcot-Marie-Tooth disease type 4J (OMIM 611228) is a recessive, potentially severe form of the disease caused by mutations of the lipid phosphatase FIG4. We provide a more complete view of the features of this disorder by describing 11 previously unreported patients with Charcot-Marie-Tooth disease type 4J. Three patients were identified from a small cohort selected for screening because of their early onset disease and progressive proximal as well as distal weakness. Eight patients were identified by large-scale exon sequencing of an unselected group of 4000 patients with Charcot-Marie-Tooth disease. In addition, 34 new FIG4 variants were detected. Ten of the new CMT4J cases have the compound heterozygous genotype FIG4(I41T/null) described in the original four families, while one has the novel genotype FIG4(L17P/nul)(l). The population frequency of the I41T allele was found to be 0.001 by genotyping 5769 Northern European controls. Thirty four new variants of FIG4 were identified. The severity of Charcot-Marie-Tooth disease type 4J ranges from mild clinical signs to severe disability requiring the use of a wheelchair. Both mild and severe forms have been seen in patients with the same genotype. The results demonstrate that Charcot-Marie-Tooth disease type 4J is characterized by highly variable onset and severity, proximal as well as distal and asymmetric muscle weakness, electromyography demonstrating denervation in proximal and distal muscles, and frequent progression to severe amyotrophy. FIG4 mutations should be considered in Charcot-Marie-Tooth patients with these characteristics, especially if found in combination with sporadic or recessive inheritance, childhood onset and a phase of rapid progression.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5397.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5396.phpEarly mortality in Duchenne muscular dystrophy (DMD) is related to cardiac and respiratory complications. A phase IIa double-blind randomized placebo-controlled clinical trial was conducted to investigate the tolerability and efficacy of idebenone therapy in children with DMD. Twenty-one DMD patients (aged 8-16years) were randomly assigned to daily treatment with 450mg idebenone (Catena®) (n=13) or placebo (n=8) for 12months. All subjects completed the study and idebenone was safe and well tolerated. Idebenone treatment resulted in a trend (p=0.067) to increase peak systolic radial strain in the left ventricular inferolateral wall, the region of the heart that is earliest and most severely affected in DMD. A significant respiratory treatment effect on peak expiratory flow was observed (p=0.039 for PEF and p=0.042 for PEF percent predicted). Limitations of this study were the small sample size, and a skewed age distribution between treatment groups. Data from this study provided the basis for the planning of a confirmatory study.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5396.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5395.phpMany clinical features of autosomal centronuclear myopathies (CNM) and X-linked myotubular myopathy (XLMTM) are common to congenital myasthenic syndromes (CMS). We describe three children whose clinical and electrophysiological findings originally suggested CMS, in whom CNM was diagnosed pathologically, though not yet genetically characterised. A fourth case, with XLMTM, also showed electrophysiological features of a neuromuscular transmission defect. Three (including the XLMTM case) showed improved strength with acetylcholinesterase inhibitor treatment. We also studied neuromuscular junction structure and function in the MTM1 knockdown zebrafish model of XLMTM, demonstrating abnormal neuromuscular junction organization; anticholinesterase therapy resulted in marked clinical response. These observations suggest that a neuromuscular transmission defect may accompany CNM and contribute to muscle weakness. Muscle biopsy should be considered in infants suspected to have CMS, especially if treatment response is incomplete, or no CMS gene mutation is identified. Treatment with acetylcholinesterase inhibitors may benefit some CNM patients. This warrants further confirmation.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5395.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5394.phpMDC1A, the second most prevalent form of congenital muscular dystrophy, results from laminin-α2 chain deficiency. This disease is characterized by extensive muscle wasting that results in extremely weak skeletal muscles. A large percentage of children with MDC1A are faced with respiratory as well as ambulatory difficulties. We investigated the effects of overexpressing insulin-like growth factor-1 (IGF-1) as a potential therapeutic target for the disease in the Lama2(Dy-w) mouse, a model that closely resembles human MDC1A. IGF-1 transgenic Lama2(Dy-w) mice showed increased survivability, body weight, and muscle weight. In addition, these mice showed better ability to stand up on their hind limbs: a typical exploratory behavior seen in healthy mice. Histology and immunohistochemistry analyses reveal increased regenerative capacity and proliferation in IGF-1 transgenic Lama2(Dy-w) muscles. Western blot analysis showed increased phosphorylation of Akt and ERK1/2, both known to enhance myogenesis. Additionally, we saw increases in the expression of the regeneration markers MyoD, Myogenin and embryonic myosin (MYH3). We conclude that overexpression of IGF-1 in Lama2(Dy-w) mice increases lifespan and improves their overall wellbeing mainly through the restoration of impaired muscle regeneration as fibrosis or inflammation were not impacted by IGF-1 in this disease model. Our results demonstrate that IGF-1 has a promising therapeutic potential in the treatment of MDC1A.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5394.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5393.phpOBJECTIVES: To assess characteristics and outcome of interstitial lung disease (ILD) in polymyositis (PM) and dermatomyositis (DM). To determine predictive variables of ILD deterioration in PM/DM.METHODS: Among 348 consecutive patients with PM/DM, the medical records of 107 patients with ILD in 4 medical centers were identified. All patients had underwent pulmonary function tests (PFT) and pulmonary high resolution computed tomography (HRCT)-scan.RESULTS: ILD onset preceded PM/DM clinical manifestations in 20 patients, was concurrently identified in association with PM/DM in 69 patients and developed after PM/DM in 18 patients. Patients with ILD could be divided into 3 groups according to their presenting lung manifestations: acute lung disease (n=20), progressive-course lung signs (n=45), and asymptomatic patients exhibiting abnormalities consistent with ILD on PFT and HRCT-scan (n=32). We observed that 32.7% of patients had resolution of pulmonary disorders, whereas 15.9% experienced ILD deterioration. Poor prognostic parameters of ILD were: older age, symptomatic ILD, lower values of vital capacity and DLCO, pattern of usual interstitial pneumonia on HRCT-scan and lung biopsy, and steroid-refractory ILD. Mortality rate was higher in patients with ILD deterioration (47.5% vs. 3.3%).CONCLUSION: Our series underlines that ILD results in high morbidity in PM/DM. Our findings also suggest interestingly that PM/DM patients presenting with factors predictive of ILD poor outcome may require more aggressive therapy.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5393.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5392.phpOBJECTIVE: To characterize the short-term course of spinal muscular atrophy (SMA) in a genetically and clinically well-defined cohort of patients with SMA. DESIGN: A comprehensive multicenter, longitudinal, observational study. SETTING: The Pediatric Neuromuscular Clinical Research Network for SMA, a consortium of clinical investigators at 3 clinical sites. PARTICIPANTS: Sixty-five participants with SMA types 2 and 3, aged 20 months to 45 years, were prospectively evaluated. Intervention We collected demographic and medical history information and determined the SMN 2 copy number. MAIN OUTCOME MEASURES: Clinical outcomes included measures of motor function (Gross Motor Function Measure and expanded Hammersmith Functional Motor Scale), pulmonary function (forced vital capacity), and muscle strength (myometry). Participants were evaluated every 2 months for the initial 6 months and every 3 months for the subsequent 6 months. We evaluated change over 12 months for all clinical outcomes and examined potential correlates of change over time including age, sex, SMA type, ambulatory status, SMN2 copy number, medication use, and baseline function. RESULTS: There were no significant changes over 12 months in motor function, pulmonary function, and muscle strength measures. There was evidence of motor function gain in ambulatory patients, especially in those children younger than 5 years. Scoliosis surgery during the observation period led to a subsequent decline in motor function. CONCLUSIONS: Our results confirm previous clinical reports suggesting that SMA types 2 and 3 represent chronic phenotypes that have relatively stable clinical courses. We did not detect any measurable clinical disease progression in SMA types 2 and 3 over 12 months, suggesting that clinical trials will have to be designed to measure improvement rather than stabilization of disease progression. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5392.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5391.phpMyofibrillar myopathies (MFM) are a group of disorders associated with mutations in DES, CRYAB, MYOT, ZASP, FLNC, or BAG3 genes and characterized by disintegration of myofibrils and accumulation of degradation products into intracellular inclusions. We retrospectively evaluated 53 MFM patients from 35 Spanish families. Studies included neurologic exam, muscle imaging, light and electron microscopic analysis of muscle biopsy, respiratory function testing and cardiologic work-up. Search for pathogenic mutations was accomplished by sequencing of coding regions of the six genes known to cause MFM. Mutations in MYOT were the predominant cause of MFM in Spain affecting 18 of 35 families, followed by DES in 11 and ZASP in 3; in 3 families the cause of MFM remains undetermined. Comparative analysis of DES, MYOT and ZASP associated phenotypes demonstrates substantial phenotypic distinctions that should be considered in studies of disease pathogenesis, for optimization of subtype-specific treatments and management, and directing molecular analysis.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5391.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5390.phpMyotonic dystrophy is an RNA gain-of-function disease caused by expanded CUG or CCUG repeats, which sequester the RNA binding protein MBNL1. Here we describe a newly discovered function for MBNL1 as a regulator of pre-miR-1 biogenesis and find that miR-1 processing is altered in heart samples from people with myotonic dystrophy. MBNL1 binds to a UGC motif located within the loop of pre-miR-1 and competes for the binding of LIN28, which promotes pre-miR-1 uridylation by ZCCHC11 (TUT4) and blocks Dicer processing. As a consequence of miR-1 loss, expression of GJA1 (connexin 43) and CACNA1C (Cav1.2), which are targets of miR-1, is increased in both DM1- and DM2-affected hearts. CACNA1C and GJA1 encode the main calcium- and gap-junction channels in heart, respectively, and we propose that their misregulation may contribute to the cardiac dysfunctions observed in affected persons.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5390.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5389.phpSpinal muscular atrophy (SMA) is a neuromuscular disorder caused by reduced levels of the survival motor neuron (SMN) protein. Here we show that the proteasome inhibitor, bortezomib, increases SMN in cultured cells and in peripheral tissues of SMA model mice. Bortezomib-treated animals had improved motor function, which was associated with reduced spinal cord and muscle pathology and improved neuromuscular junction size, but no change in survival. Combining bortezomib with the histone deacetylase inhibitor trichostatin A resulted in a synergistic increase in SMN protein levels in mouse tissue and extended survival of SMA mice more than trichostatin A alone. Our results demonstrate that a combined regimen of drugs that decrease SMN protein degradation and increase SMN gene transcription synergistically increases SMN levels and improves the lifespan of SMA model mice. Moreover, this study indicates that while increasing SMN levels in the central nervous system may help to extend survival, peripheral tissues can also be targeted to improve the SMA disease phenotype.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5389.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5388.phpStudy Objective: To describe survival outcomes by using noninvasive intermittent positive pressure ventilation (IPPV) for full ventilatory support, and a mechanically assisted coughing (MAC)/oximetry protocol for a series of patients with Duchenne muscular dystrophy (DMD). METHODS: End-tidal carbon dioxide (EtCO©ü), oximetry (SpO©ü), vital capacity (VC), maximum insufflation capacity (MIC), and cough peak flows (CPF) were monitored. Nocturnal NIV was initiated for symptomatic hypoventilation. An oximeter and MAC were prescribed for maximum assisted CPF<300 L/m. Patients used up to continuous noninvasive IPPV and used MAC to return SpO©ü ˇĂ 95% during intercurrent respiratory infections (RTIs) or as otherwise needed. Respiratory and cardiac hospitalizations and mortality were noted. Survival was quantitated by duration of noninvasive IPPV dependence without ventilator-free breathing ability (VFBA). RESULTS: With advancing disease, 101 nocturnal-only noninvasive IPPV users extended use throughout daytime hours and required it continuously for 7.4ˇľ6.1 years to 30.1ˇľ6.1 years of age with 56 patients still alive. Twenty-six of the 101 became continuously dependent without requiring hospitalization. Eight continuous tracheostomy IPPV users were decannulated to noninvasive IPPV. Thirty-one consecutive "unweanable" intubated patients were extubated to noninvasive IPPV/MAC. Of the 67 deaths including eight patients who died from heart failure before requiring ventilator use, 34 (52%) were probably cardiac, 14 (21%) probably respiratory, and 19 (27%) of unknown or other etiology. CONCLUSIONS: Continuous noninvasive IPPV along with MAC/oximetry as needed can prolong life and eliminate need to resort to tracheotomy for patients with DMD. Unweanable patients can be decannulated and extubated to NIV/MAC. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5388.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5387.phpCombination of stem cell-based approaches with gene-editing technologies represents an attractive strategy for studying human disease and developing therapies. However, gene-editing methodologies described to date for human cells suffer from technical limitations including limited target gene size, low targeting efficiency at transcriptionally inactive loci, and off-target genetic effects that could hamper broad clinical application. To address these limitations, and as a proof of principle, we focused on homologous recombination-based gene correction of multiple mutations on lamin A (LMNA), which are associated with various degenerative diseases. We show that helper-dependent adenoviral vectors (HDAdVs) provide a highly efficient and safe method for correcting mutations in large genomic regions in human induced pluripotent stem cells and can also be effective in adult human mesenchymal stem cells. This type of approach could be used to generate genotype-matched cell lines for disease modeling and drug discovery and potentially also in therapeutics.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5387.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5386.phpDynamin 2 (DNM2) is a large GTPase implicated in many cellular functions, including cytoskeleton regulation and endocytosis. Although ubiquitously expressed, DNM2 was found mutated in two genetic disorders affecting different tissues: autosomal dominant centronuclear myopathy (ADCNM; skeletal muscle) and peripheral Charcot-Marie-Tooth neuropathy (peripheral nerve). To gain insight into the function of DNM2 in skeletal muscle and the pathological mechanisms leading to ADCNM, we introduced wild-type DNM2 (WT-DNM2) or R465W DNM2 (RW-DNM2), the most common ADCNM mutation, into adult wild-type mouse skeletal muscle by intramuscular adeno-associated virus injections. We detected altered localization of RW-DNM2 in mouse muscle. Several ADCNM features were present in RW-DNM2 mice: fiber atrophy, nuclear mislocalization, and altered mitochondrial staining, with a corresponding reduction in specific maximal muscle force. The sarcomere and triad structures were also altered. We report similar findings in muscle biopsy specimens from an ADCNM patient with the R465W mutation. In addition, expression of wild-type DNM2 induced some muscle defects, albeit to a lesser extent than RW-DNM2, suggesting that the R465W mutation has enhanced activity in vivo. In conclusion, we show the RW-DNM2 mutation acts in a dominant manner to cause ADCNM in adult muscle, and the disease arises from a primary defect in skeletal muscle rather than secondary to peripheral nerve involvement. Therefore, DNM2 plays important roles in the maintenance of adult muscle fibers.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5386.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5385.phpINTRODUCTION: An association is observed between the severity of myotonic dystrophy type 1 (DM1) and the genetic abnormality of cytosine-thymine-guanine (CTG) repeat expansion. It is unknown whether an association exists between survival and CTG repeat expansion. METHODS: In an adult 406-patient DM1 cohort, the phenotype, including survival age, was evaluated in relation to CTG repeat expansion. RESULTS: At study entry, age was 42 ± 12 (range 18-78) years, with a CTG repeat length of 629 ± 386 (range 54-1965). An inverse correlation was observed between CTG repeat length and the age at onset and younger DM1 phenotype. Over a follow-up of 9.2 ± 3.1 years, 118 (29.1%) patients died, including 60 of neuromuscular respiratory failure, 41 of cardiac causes, and 17 of non-neuromuscular, non-cardiac causes. There was an inverse relationship between all-cause survival and CTG length (relative risk 5.4 per log repeat, 95% confidence interval 2.9-10.2, P < 0.001). CONCLUSION: The data demonstrate a genotype-mortality association in DM1. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5385.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5384.phpOBJECTIVE: A recessively transmitted fatal hypertonic infantile muscular dystrophy has been described in Canadian aboriginals. The affected infants present with progressive limb and axial muscle stiffness and develop severe respiratory insufficiency, and most die in the first year of life. We sought to determine the genetic basis of this disease. METHODS: We performed histochemical, immunocytochemical, electron microscopy, and molecular genetic studies in a cohort of 12 patients affected by this disease. RESULTS: Conventional histochemical and electron microscopy studies suggested myofibrillar myopathy (MFM). Therefore, we searched for ectopic expression of multiple proteins typical of MFM. Alpha B-crystallin (áBC) expression was absent from all fibres using a monoclonal antibody raised against the entire protein. However, a monoclonal antibody directed against the first 10 residues of áBC immunostained portions of abnormal fibres. Pursuing this clue, we searched for mutations in the gene for áBC (CRYAB) in available DNA samples of 8 patients. All harbored a homozygous deletion, c.60C, predicting a Ser to Ala change at codon 21 and a stop codon after 23 missense residues (p.Ser21AlafsX24). Clinically unaffected parents were heterozygous for this mutation. INTERPRETATION: The homozygous c.60delC in CRYAB pinpoints the genetic basis of the fatal infantile hypertonic muscular dystrophy of Canadian aboriginals. MFMs are typically transmitted by dominant inheritance, but in this disease the parental phenotype is rescued by limited expression of the highly truncated nonfunctional mutant gene product. The severe patient phenotype is due to homozygosity for the markedly hypomorphic allele. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5384.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5383.phpSpinal muscular atrophy (SMA), a neurodegenerative disorder primarily affecting motor neurons, is the most common genetic cause of infant death. This incurable disease is caused by the absence of a functional SMN1gene and a reduction in full length SMN protein. In this study, a neuroprotective function of SMN was investigated in differentiated human SH-SY5Y cells using an adenoviral vector to over-express SMN protein. The pro-survival capacity of SMN was assessed in an Akt/PI3-kinase inhibition (LY294002) model, as well as an oxidative stress (hydrogen peroxide) and excitotoxic (glutamate) model. SMN over-expression in SH-SY5Y cells protected against Akt/PI3-kinase inhibition, but not oxidative stress, nor against excitotoxicity in rat cortical neurons. Western analysis of cell homogenates from SH-SY5Y cultures over-expressing SMN harvested pre- and post- Akt/PI3-kinase inhibition indicated that SMN protein inhibited caspase-3 activation via blockade of calpain mediated procaspase-3 cleavage. This study has revealed a novel anti-apoptotic function for the SMN protein in differentiated SH-SY5Y cells. Finally, the cell death model described herein will allow the assessment of future therapeutic agents or strategies aimed at increasing SMN protein levels. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5383.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5382.phpSpinal muscular atrophy (SMA) is an inherited motor neuron disease caused by the mutation of the survival motor neuron 1 (SMN1) gene and deficiency of the SMN protein. Severe SMA mice have abnormal motor function and small, immature myofibers early in development suggesting that SMN protein deficiency results in retarded muscle growth. Insulin-like growth factor 1 (IGF-1) stimulates myoblast proliferation, induces myogenic differentiation, and generates myocyte hypertrophy in vitro and in vivo. We hypothesized that increased expression of IGF-1 specifically in skeletal muscle would attenuate disease features of SMAÄ7 mice. SMAÄ7 mice overexpressing a local isoform of IGF-1 (mIGF-1) in muscle showed enlarged myofibers and a 40% increase in median survival compared to mIGF-1 negative SMA littermates (median survival = 14 vs. 10 days respectively, log rank p=0.025). Surprisingly, this was not associated with a significant improvement in motor behavior. Treatment of both mIGF-1(NEG) and mIGF-1(POS) SMA mice with the histone deacetylase inhibitor, trichostatin A (TSA), resulted in a further extension of survival and improved motor behavior, but the combination of mIGF-1 and TSA treatment was not synergistic. These results show that increased mIGF-1 expression restricted to muscle can modulate the phenotype of SMA mice indicating that therapeutics targeted to muscle alone should not be discounted as potential disease-modifying therapies in SMA. IGF-1 may warrant further investigation in mild SMA animal models and perhaps SMA patients. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5382.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5381.phpThe objective is to refine the clinical and morphological phenotype and the chromosomal region of interest, in the recently reported 7q36 linked autosomal dominant limb-girdle muscular dystrophy (LGMD1 D/E), by describing four new informative Finnish families. Examinations of the patients included serum CK, neurophysiological studies, cardiac and respiratory function examinations, muscle biopsies and muscle imaging. DNA samples were analyzed by genotyping. Patients in all families had very similar phenotypes with onset of muscle weakness in the pelvic girdle muscles between the fourth and sixth decade, later involvement of the shoulder girdle, and marked walking difficulties in the eighth decade. Muscle biopsies showed myopathic and/or dystrophic features. Genotyping confirmed linkage to the same locus at chromosome 7q36 in all families by one identically segregating haplotype. The linked region was narrowed down from <6.3 to <3.4Mb. Sequencing of the genes in the area is ongoing, aiming to identify the genetic defect.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5381.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5380.phpDuchenne muscular dystrophy is a recessive X-linked genetic disease caused by dystrophin gene mutations. Cell therapy can be a potential approach aiming to introduce a functional dystrophin in the dystrophic patient myofibers. However, this strategy produced so far limited results. Transforming growth factor â (TGF-â) is a negative regulator of skeletal-muscle development and is responsible for limiting myogenic regeneration. The combination of TGF-â signaling inhibition with myoblast transplantation can be an effective therapeutic approach in dystrophin deficient patients. Our aim was to verify whether the success of human myoblast transplantation in immunodeficient dystrophic mice is enhanced with losartan, a molecule that down-regulates TGF-â expression. In vitro, blocking TGF-â activity with losartan increased proliferation and fusion and decreased apoptosis in human myoblasts. In vivo, human myoblasts were transplanted in mice treated with oral losartan. Immunodetection of human dystrophin in Tibialis anterior cross-sections 1 month post-transplantation revealed more human dystrophin-positive myofibers in these mice than in non-treated dystrophic mice. Thus blocking the TGF-â signal with losartan treatment improved the success of myoblast transplantation probably by increasing myoblast proliferation and fusion, decreasing macrophage activation and changing the expression of myogenic regulator factors.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5380.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5379.phpBackground: Local intramuscular administration of the antisense oligonucleotide PRO051 in patients with Duchenne's muscular dystrophy with relevant mutations was previously reported to induce the skipping of exon 51 during pre-messenger RNA splicing of the dystrophin gene and to facilitate new dystrophin expression in muscle-fiber membranes. The present phase 1-2a study aimed to assess the safety, pharmacokinetics, and molecular and clinical effects of systemically administered PRO051. Methods We administered weekly abdominal subcutaneous injections of PRO051 for 5 weeks in 12 patients, with each of four possible doses (0.5, 2.0, 4.0, and 6.0 mg per kilogram of body weight) given to 3 patients. Changes in RNA splicing and protein levels in the tibialis anterior muscle were assessed at two time points. All patients subsequently entered a 12-week open-label extension phase, during which they all received PRO051 at a dose of 6.0 mg per kilogram per week. Safety, pharmacokinetics, serum creatine kinase levels, and muscle strength and function were assessed. Results The most common adverse events were irritation at the administration site and, during the extension phase, mild and variable proteinuria and increased urinary ?(1)-microglobulin levels; there were no serious adverse events. The mean terminal half-life of PRO051 in the circulation was 29 days. PRO051 induced detectable, specific exon-51 skipping at doses of 2.0 mg or more per kilogram. New dystrophin expression was observed between approximately 60% and 100% of muscle fibers in 10 of the 12 patients, as measured on post-treatment biopsy, which increased in a dose-dependent manner to up to 15.6% of the expression in healthy muscle. After the 12-week extension phase, there was a mean (±SD) improvement of 35.2±28.7 m (from the baseline of 384±121 m) on the 6-minute walk test. Conclusions Systemically administered PRO051 showed dose-dependent molecular efficacy in patients with Duchenne's muscular dystrophy, with a modest improvement in the 6-minute walk test after 12 weeks of extended treatment. (Funded by Prosensa Therapeutics; Netherlands National Trial Register number, NTR1241).Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5379.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5378.phpMyotonic dystrophy type 1 (DM1) is a multisystem disorder affecting a variety of organs, including the central nervous system. By using neuronal progeny derived from human embryonic stem cells carrying the causal DM1 mutation, we have identified an early developmental defect in genes involved in neurite formation and the establishment of neuromuscular connections. Differential gene expression profiling and quantitative RT-PCR revealed decreased expression of two members of the SLITRK family in DM1 neural cells and in DM1 brain biopsies. In addition, DM1 motoneuron/muscle cell cocultures showed alterations that are consistent with the known role of SLITRK genes in neurite outgrowth, neuritogenesis, and synaptogenesis. Rescue and knockdown experiments suggested that the functional defects can be directly attributed to SLITRK misexpression. These neuropathological mechanisms may be clinically significant for the functional changes in neuromuscular connections associated with DM1.Mutant human embryonic stem cells reveal neurite and synapse formation defects in type 1 myotonic dystrophy. Marteyn A, Maury Y, Gauthier MM, Lecuyer C, Vernet R, Denis JA, Pietu G, Peschanski M, Martinat C. Cell Stem Cell. 2011 Apr 8;8(4):434-44. http://www.ncbi.nlm.nih.gov/pubmed/21458401Myotonic dystrophy type 1 (DM1) is a multisystem disorder affecting a variety of organs, including the central nervous system. By using neuronal progeny derived from human embryonic stem cells carrying the causal DM1 mutation, we have identified an early developmental defect in genes involved in neurite formation and the establishment of neuromuscular connections. Differential gene expression profiling and quantitative RT-PCR revealed decreased expression of two members of the SLITRK family in DM1 neural cells and in DM1 brain biopsies. In addition, DM1 motoneuron/muscle cell cocultures showed alterations that are consistent with the known role of SLITRK genes in neurite outgrowth, neuritogenesis, and synaptogenesis. Rescue and knockdown experiments suggested that the functional defects can be directly attributed to SLITRK misexpression. These neuropathological mechanisms may be clinically significant for the functional changes in neuromuscular connections associated with DM1.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5378.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5377.phpBACKGROUND: A 43-year-old woman suffering from Steinert syndrome was admitted after experiencing multiple episodes of torsades de pointes-related syncope. OBJECTIVES: To elucidate the pathophysiology of these arrhythmic events. METHODS AND RESULTS: We obtained DNA from the patient and sequenced the coding region of KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 genes. A single nucleotide change was identified in the KCNQ1 gene at position 608 (T608C), resulting in a substitution from leucine to proline at position 203 (L203P). CHO cells were used to express either wild-type KCNQ1, wild-type KCNQ1+L203P KCNQ1 (50:50), or L203P KCNQ1, along with KCNE1 to recapitulate the slow cardiac delayed rectifier potassium current (I(Ks)). Patch-clamp experiments showed that the variant L203P causes a dominant negative effect on I(Ks). Coexpression of wild-type KCNQ1 and L203P KCNQ1 (50:50) caused a ~75% reduction in current amplitude when compared to wild-type KCNQ1 alone (131.40 ± 23.27 vs 567.25 ± 100.65 pA/pF, P < .001). Moreover, when compared with wild-type KCNQ1 alone, the coexpression of wild-type KCNQ1 and L203P KCNQ1 (50:50) caused a 7.5-mV positive shift of midpoints of activation (from 27.5 ± 2.4 to 35.1 ± 1.2 mV, P < .05). The wild-type KCNQ1 and L203P KCNQ1 (50:50) coexpression also caused alteration of I(Ks) kinetics. The activation kinetics of the L203P variant (50:50) were slowed compared with wild-type KCNQ1, while the deactivation kinetics of L203P (50:50) were accelerated compared with wild type, all these further contributing to the "loss-of-function" phenotype of I(Ks) associated with the variant L203P. CONCLUSION: Torsades de pointes and episodes of syncope are very likely to be due to the KCNQ1 variant L203P found in this patient.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5377.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5376.phpDilated cardiomyopathy (DCM) is a major cause of heart failure with a high familial recurrence risk. So far, the genetics of DCM remains largely unresolved. We conducted the first genome-wide association study (GWAS) to identify loci contributing to sporadic DCM. Methods and results One thousand one hundred and seventy-nine DCM patients and 1108 controls contributed to the discovery phase. Pools of DNA stratified on disease status, population, age, and gender were constituted and used for testing association of DCM with 517 382 single nucleotide polymorphisms (SNPs). Three DCM-associated SNPs were confirmed by individual genotyping (P < 5.0 10(-7)), and two of them, rs10927875 and rs2234962, were replicated in independent samples (1165 DCM patients and 1302 controls), with P-values of 0.002 and 0.009, respectively. rs10927875 maps to a region on chromosome 1p36.13 which encompasses several genes among which HSPB7 has been formerly suggested to be implicated in DCM. The second identified locus involves rs2234962, a non-synonymous SNP (c.T757C, p. C151R) located within the sequence of BAG3 on chromosome 10q26. To assess whether coding mutations of BAG3 might cause monogenic forms of the disease, we sequenced BAG3 exons in 168 independent index cases diagnosed with familial DCM and identified four truncating and two missense mutations. Each mutation was heterozygous, present in all genotyped relatives affected by the disease and absent in a control group of 347 healthy individuals, strongly suggesting that these mutations are causing the disease. Conclusion This GWAS identified two loci involved in sporadic DCM, one of them probably implicates BAG3. Our results show that rare mutations in BAG3 contribute to monogenic forms of the disease, while common variant(s) in the same gene are implicated in sporadic DCM.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5376.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5375.phpDuchenne muscular dystrophy (DMD) is an inherited severe muscle wasting disorder with, thus far, no effective therapy. DMD causes respiratory and cardiac failure as well as muscle wastage. Among the various symptoms, respiratory insufficiency is a major cause of death in DMD patients at about 20 years of age. So, naturally, the improvement of respiratory function will extend the patient's life. We report here, for the first time, a sensitive procedure using whole-body plethysmography to monitor respiratory parameters detected in the utrophin/dystrophin double knockout mouse (dko mouse), showing quite similar systemic symptoms to human DMD including restrictive ventilatory impairment. Furthermore, we show that a highly efficient dystrophin-transduction to the dko's diaphragm-achieved by simple intraperitoneal injection of a helper-dependent adenovirus vector (HDAdv) containing the full-length dystrophin expression cassette-provided beneficial results. In spite of dystrophin expression only in the diaphragm, this focal gene transfer could result in the rescue from ventilatory impairment (increased tidal volume (TV) and improvement of compensatory hyperpnea). Our result suggests that a DMD patient's mortal ventilatory impairment may be improved via technically easy means through the intraperitoneal injection of HDAdv.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5375.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5374.phpAs the first step in prenatal diagnosis of X-linked genetic disorders, chorionic villus sampling (CVS) for foetal sex determination is generally performed at 11-13 weeks of gestation. However, as the procedure-related miscarriage rate of CVS is 0.5-1.0%, non-invasive methods such as PCR of cell-free foetal DNA (cff-DNA) in maternal plasma are preferable. Here, we determined foetal sex at 9-12 weeks of gestation using PCR of cff-DNA in three pregnant carriers of Duchenne muscular dystrophy. The foetal sex was accurately determined in all three cases, as confirmed by ultrasound and amniocentesis at 16 weeks (for the two female foetuses) and CVS at 12 weeks (for the one male foetus). This procedure could avoid unnecessary CVS in female foetuses.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5374.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5373.php Biogen Idec is recruiting participants for its EMPOWER trial, which will study the effects of the experimental treatment dexpramipexole in ALS. EMPOWER, a large-scale, global phase 3 clinical trial of a molecule called dexpramipexole in ALS (amyotrophic lateral sclerosis, or Lou Gehrig's disease), has begun recruiting participants. The trial will be conducted at study sites in 28 U.S. states and 10 other countries, under the auspices of the biotech firm Biogen Idec, headquartered in Weston, Mass. The molecule, which has demonstrated favourable effects in phase 1 and 2 human clinical trials, received "orphan drug" designation from the U.S. Food and Drug Administration in October 2007, and "fast-track" designation in September 2009. Dexpramipexole, also known as (R+) pramipexole, was developed under the name KNS-760704 by Knopp Biosciences (then called Knopp Neurosciences) of Pittsburgh. Dexpramipexole's chemical structure is the mirror image of Mirapex, a prescription drug approved for the treatment of Parkinson disease and restless legs syndrome. The structural difference between the two molecules results in significantly different pharmacological effects. Mirapex, also known as (S-) pramipexole, mimics the actions of dopamine, which would be an undesirable strategy for ALS. Although its mechanism of action in ALS remains unclear, dexpramipexole has demonstrated neuroprotective properties in multiple studies involving cell cultures and laboratory animals. It may work by improving the function and efficiency of mitochondria. In ALS, mitochondria endure oxidative stress. It's suspected that dexpramipexole may help maintain energy production in stressed mitochondria within motor neurons. This phase 3 trial in the United States, Canada, Europe and Australia is slated to include approximately 800 people with ALS, who will be randomly assigned to one of two groups. In the treatment group, trial participants will receive 150 mg twice daily of dexpramipexole; those in the control group will receive a placebo. Everyone enrolled in the study will be followed for a period of 12-18 months. Researchers will assess trial participants using the ALS Revised Functional Rating Scale (ALSFRS-R), a validated ratings scale used by physicians to monitor the progression of disability in individuals with ALS. They also will assess effects on survival and functional decline, and will characterize the molecule's pharmacokinetics. Contact informationContact the medical director for the EMPOWER study at ALSclinicaltrials@biogenidec.com; or call Biogen Idec Patient Services at (877) 312-9676 and select option 2 from within the United States. If calling from outside the United States, use +1 (919) 993-7311 and select option 2.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5373.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5372.phpA team of researchers at the David Geffen School of Medicine at the University of California-Los Angeles (UCLA) has demonstrated that the naturally occurring protein interleukin 10 (IL10) may help reduce harmful inflammation and promote muscle regeneration in people with Duchenne muscular dystrophy (DMD), and potentially those with other forms of muscular dystrophy. Corticosteroids (such as prednisone) commonly are used in DMD and help preserve muscle strength and function. It's thought that they work, at least in part, by reducing inflammation. However, corticosteroids also cause unwanted side effects such as increased appetite, weight gain, loss of bone mass and cataracts. Tidball and colleagues conducted experiments in both cell culture and mouse model of DMD to determine the effects of the IL10 protein on macrophages. Various types of macrophages play key roles in muscle health. "M1" macrophages cause harmful inflammation leading to increased muscle damage, and "M2c" macrophages are involved in muscle repair. Previous research has shown that the IL10 protein regulates macrophages; one of its primary functions is to suppress the muscle-damaging M1 type and activate the M2c macrophages that stimulate muscle regeneration and repair. To further study the balance of macrophage types regulated by IL10, the UCLA team created mice lacking the IL10 protein. Upon examination, they found these mice had more active M1 macrophages, more muscle damage and less muscle strength than DMD mice with normal IL10 levels. The researchers reported that the beneficial effects of IL10 are due to the protein's ability to influence the balance between M1 and M2c macrophages. Treatment strategies that reduce inflammation appear to lessen muscle damage in DMD patients. The authors note that IL10-based therapeutic strategies designed to reduce inflammation could prove beneficial in DMD and perhaps in other forms of MD.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5372.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5371.phpThe Ras superfamily of guanosine-triphosphate (GTP)-binding proteins regulates a diverse spectrum of intracellular processes involved in inflammation and fibrosis. Farnesythiosalicylic acid (FTS) is a unique and potent Ras inhibitor which decreased inflammation and fibrosis in experimentally induced liver cirrhosis and ameliorated inflammatory processes in systemic lupus erythematosus, neuritis and nephritis animal models. FTS effect on Ras expression and activity, muscle strength and fibrosis was evaluated in the dy(2J)/dy(2J) mouse model of merosin deficient congenital muscular dystrophy. The dy(2J)/dy(2J) mice had significantly increased RAS expression and activity compared with the wild type mice. FTS treatment significantly decreased RAS expression and activity. In addition, phosphorylation of ERK, a Ras downstream protein, was significantly decreased following FTS treatment in the dy(2J)/dy(2J) mice. Clinically, FTS treated mice showed significant improvement in hind limb muscle strength measured by electronic grip strength meter. Significant reduction of fibrosis was demonstrated in the treated group by quantitative Sirius Red staining and lower muscle collagen content. FTS effect was associated with significantly inhibition of both MMP-2 and MMP-9 activities. We conclude that active RAS inhibition by FTS was associated with attenuated fibrosis and improved muscle strength in the dy(2J)/dy(2J) mouse model of congenital muscular dystrophy.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5371.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5370.phpNeuromuscular junctions (NMJs) are synapses that transmit impulses from motor neurons to skeletal muscle fibers leading to muscle contraction. Study of hereditary disorders of neuromuscular transmission, termed congenital myasthenic syndromes (CMS), has helped elucidate fundamental processes influencing development and function of the nerve-muscle synapse. Using genetic linkage, we find 18 different biallelic mutations in the gene encoding glutamine-fructose-6-phosphate transaminase 1 (GFPT1) in 13 unrelated families with an autosomal recessive CMS. Consistent with these data, downregulation of the GFPT1 ortholog gfpt1 in zebrafish embryos altered muscle fiber morphology and impaired neuromuscular junction development. GFPT1 is the key enzyme of the hexosamine pathway yielding the amino sugar UDP-N-acetylglucosamine, an essential substrate for protein glycosylation. Our findings provide further impetus to study the glycobiology of NMJ and synapses in general.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5370.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5369.phpBACKGROUND: Spinal muscular atrophy (SMA) is the most common neuromuscular autosomal recessive disorder. The American College of Medical Genetics has recently recommended routine carrier screening for SMA because of the high carrier frequency (1 in 25-50) as well as the severity of that genetic disease. Large studies are needed to determine the feasibility, benefits, and costs of such a program.METHODS AND FINDINGS: This is a prospective population-based cohort study of 107,611 pregnant women from 25 counties in Taiwan conducted during the period January 2005 to June 2009. A three-stage screening program was used: (1) pregnant women were tested for SMA heterozygosity; (2) if the mother was determined to be heterozygous for SMA (carrier status), the paternal partner was then tested; (3) if both partners were SMA carriers, prenatal diagnostic testing was performed. During the study period, a total of 2,262 SMA carriers with one copy of the SMN1 gene were identified among the 107,611 pregnant women that were screened. The carrier rate was approximately 1 in 48 (2.10%). The negative predictive value of DHPLC coupled with MLPA was 99.87%. The combined method could detect approximately 94% of carriers because most of the cases resulted from a common single deletion event. In addition, 2,038 spouses were determined to be SMA carriers. Among those individuals, 47 couples were determined to be at high risk for having offspring with SMA. Prenatal diagnostic testing was performed in 43 pregnant women (91.49%) and SMA was diagnosed in 12 (27.91%) foetuses. The prevalence of SMA in our population was 1 in 8,968.CONCLUSION: The main benefit of SMA carrier screening is to reduce the burden associated with giving birth to an affected child. In this study, we determined the carrier frequency and genetic risk and provided carrier couples with genetic services, knowledge, and genetic counseling.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5369.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5368.phpSpinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by mutations in the SMN1 gene that result in a deficiency of SMN protein. One approach to treat SMA is to use antisense oligonucleotides (ASOs) to redirect the splicing of a paralogous gene, SMN2, to boost production of functional SMN. Injection of a 2'-O-2-methoxyethyl-modified ASO (ASO-10-27) into the cerebral lateral ventricles of mice with a severe form of SMA resulted in splice-mediated increases in SMN protein and in the number of motor neurons in the spinal cord, which led to improvements in muscle physiology, motor function and survival. Intrathecal infusion of ASO-10-27 into cynomolgus monkeys delivered putative therapeutic levels of the oligonucleotide to all regions of the spinal cord. These data demonstrate that central nervous system-directed ASO therapy is efficacious and that intrathecal infusion may represent a practical route for delivering this therapeutic in the clinic.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5368.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5367.phpNew research suggests that the DNA of a normally dormant virus may be playing a role in causing amyotrophic lateral sclerosis (ALS). If the findings are confirmed, they could ultimately have implications for treatment of the disease. The investigators examined brain tissue from 28 people who died of ALS and compared it to brain tissue from 12 people who died from other chronic systemic illnesses; 12 who died with Parkinson disease; and 10 who died from accidents or other causes without any pre-existing systemic illness. They found that the brains of those who died of ALS had significantly higher levels of a viral protein called HERV-K reverse transcriptase than did samples from any of the other groups, and that the protein was located in specific areas of the brain known to be affected in ALS. Also, the viral protein was found in the same areas as another protein, TDP43, overproduction of which has been implicated in ALS pathology. The viral protein is produced by the virus HERV-K (human endogenous retrovirus K), and is used by the virus to help it replicate. The unusual activity of HERV-K suggests that this virus could be part of the problem in sporadic ALS, the most common form of the disease and one for which the cause is unknown. Sporadic ALS accounts for 90 percent to 95 percent of cases of cases, with familial ALS accounting for the other 5 percent to 10 percent. Previous studies have found reverse transcriptase in ALS patients' serum, but they have not been linked to production by a specific set of viral genetic instructions, as has this protein. The findings open new possibilities for therapeutic targets in ALS, such as silencing the viral genetic instructions or proteins made from these instructions. Further studies are needed to clarify the role of HERV-K reverse transcriptase (and perhaps other viral proteins) in the nervous system, and whether blocking them would be helpful.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5367.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5366.phpOBJECTIVE: Facioscapulohumeral muscular dystrophy (FSHD) is associated with D4Z4 repeat contraction on human chromosome 4q35. This genetic lesion does not result in complete loss or mutation of any gene. Consequently, the pathogenic mechanisms underlying FSHD have been difficult to discern. In leading FSHD pathogenesis models, D4Z4 contractions are proposed to cause epigenetic changes, which ultimately increase expression of genes with myopathic potential. Although no gene has been conclusively linked to FSHD development, recent evidence supports a role for the D4Z4-encoded DUX4 gene in FSHD. In this study, our objective was to test the in vivo myopathic potential of DUX4.METHODS: We delivered DUX4 to zebrafish and mouse muscle by transposon-mediated transgenesis and adeno-associated viral vectors, respectively.RESULTS: Overexpression of DUX4, which encodes a transcription factor, caused abnormalities associated with muscular dystrophy in zebrafish and mice. This toxicity required DNA binding, because a DUX4 DNA binding domain mutant produced no abnormalities. Importantly, we found the myopathic effects of DUX4 were p53 dependent, as p53 inhibition mitigated DUX4 toxicity in vitro, and muscles from p53 null mice were resistant to DUX4-induced damage.INTERPRETATION: Our work demonstrates the myopathic potential of DUX4 in animal muscle. Considering previous studies showed DUX4 was elevated in FSHD patient muscles, our data support the hypothesis that DUX4 overexpression contributes to FSHD development. Moreover, we provide a p53-dependent mechanism for DUX4 toxicity that is consistent with previous studies showing p53 pathway activation in FSHD muscles. Our work justifies further investigation of DUX4 and the p53 pathway in FSHD pathogenesis. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5366.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5365.phpRecent studies showed that chronic administration of losartan, an angiotensin II type I receptor antagonist, improved skeletal muscle function in dystrophin-deficient mdx mice. In this study, C57BL/10ScSn-Dmd(mdx)/J female mice were either untreated or treated with losartan (n = 15) in the drinking water at a dose of 600 mg/L over a 6-month period. Cardiac function was assessed via in vivo high frequency echocardiography and skeletal muscle function was assessed using grip strength testing, Digiscan monitoring, Rotarod timing, and in vitro force testing. Fibrosis was assessed using picrosirius red staining and Image J analysis. Gene expression was evaluated using real-time polymerized chain reaction (RT-PCR). Percentage shortening fraction was significantly decreased in untreated (26.9% ± 3.5%) mice compared to losartan-treated (32.2% ± 4.2%; P < .01) mice. Systolic blood pressure was significantly reduced in losartan-treated mice (56 ± 6 vs 69 ± 7 mm Hg; P < .0005). Percentage cardiac fibrosis was significantly reduced in losartan-treated hearts (P < .05) along with diaphragm (P < .01), extensor digitorum longus (P < .05), and gastrocnemius (P < .05) muscles compared to untreated mdx mice. There were no significant differences in skeletal muscle function between treated and untreated groups. Chronic treatment with losartan decreases cardiac and skeletal muscle fibrosis and improves cardiac systolic function in dystrophin-deficient mdx mice.Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5365.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5364.phpBACKGROUND: Progressive muscle weakness is a main symptom of most hereditary and acquired muscle diseases. Creatine improves muscle performance in healthy individuals. This is an update of our 2007 Cochrane review that evaluated creatine treatment in muscle disorders. OBJECTIVES: To evaluate the efficacy of creatine compared to placebo for the treatment of muscle weakness in muscle diseases. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group Specialized Register (4 October 2010), the Cochrane Central Register of Controlled Trials (11 October 2010, Issue 4, 2010 in The Cochrane Library), MEDLINE (January 1966 to September 2010) and EMBASE (January 1980 to September 2010) for randomised controlled trials (RCT) of creatine used to treat muscle diseases. SELECTION CRITERIA: RCTs or quasi-RCTs of creatine treatment compared to placebo in hereditary muscle diseases or idiopathic inflammatory myopathies. DATA COLLECTION AND ANALYSIS: Two authors independently applied the selection criteria, assessed trial quality and extracted data. We obtained missing data from investigators. MAIN RESULTS: The updated searches identified two new studies. A total of 14 trials, including 364 randomised participants, met the selection criteria. Meta-analysis of six trials in muscular dystrophies including 192 participants revealed a significant increase in muscle strength in the creatine group compared to placebo, with a weighted mean difference of 8.47%; (95% confidence intervals (CI) 3.55 to 13.38). Pooled data of four trials including 115 participants showed that a significantly higher number of patients felt better during creatine treatment compared to placebo with a risk ratio of 4.51 (95% CI 2.33 to 8.74). One trial in 37 participants with idiopathic inflammatory myopathies also showed a significant improvement in functional performance. No trial reported any clinically relevant adverse event. In metabolic myopathies, meta-analyses of three cross-over trials including 33 participants revealed no significant difference in muscle strength. One trial reported a significant deterioration of ADL (mean difference 0.54 on a 1 to 10 scale; 95% CI 0.14 to 0.93) and an increase in muscle pain during high-dose creatine treatment in McArdle disease. AUTHORS' CONCLUSIONS: High quality evidence from RCTs shows that short- and medium-term creatine treatment increases muscle strength in muscular dystrophies. There is also evidence that creatine improves functional performance in muscular dystrophy and idiopathic inflammatory myopathy. Creatine is well tolerated in these people. High quality but limited evidence from RCTs does not show significant improvement in muscle strength in metabolic myopathies. High-dose creatine treatment impaired ADL and increased muscle pain in McArdle disease. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5364.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5363.phpBACKGROUND: In myasthenia gravis, antibody-mediated blockade of acetylcholine receptors at the neuromuscular junction abolishes the naturally occurring 'safety factor' of synaptic transmission. Acetylcholinesterase inhibitors provide temporary symptomatic treatment of muscle weakness, but there is controversy about their long-term efficacy, dosage and side effects. OBJECTIVES: To evaluate the efficacy of acetylcholinesterase inhibitors in all forms of myasthenia gravis. SEARCH STRATEGY: We searched The Cochrane Neuromuscular Disease Group Specialized Register (5 October 2009), The Cochrane Central Register of Controlled Trials CENTRAL) (The Cochrane Library Issue 3, 2009), MEDLINE (January 1966 to September 2009), EMBASE (January 1980 to September 2009) for randomised controlled trials and quasi-randomised controlled trials regarding usage of acetylcholinesterase inhibitors in myasthenia gravis. Two authors scanned the articles for any study eligible for inclusion. We also contacted the authors and known experts in the field to identify additional published or unpublished data. SELECTION CRITERIA: Types of studies: all randomised or quasi-randomised trials.Types of participants: all myasthenia gravis patients diagnosed by an internationally accepted definition.Types of interventions: treatment with any form of acetylcholinesterase inhibitor.Types of outcome measuresPrimary outcome measureImprovement in the presenting symptoms within 1 to 14 days of the start of treatment.Secondary outcome measures(1) Improvement in the presenting symptoms more than 14 days after the start of treatment.(2) Change in impairment measured by a recognised and preferably validated scale, such as the quantitative myasthenia gravis score within 1 to 14 days and more than 14 days after the start of treatment.(3) Myasthenia Gravis Association of America post-intervention status more than 14 days after start of treatment.(4) Adverse events: muscarinic side effects. DATA COLLECTION AND ANALYSIS: One author (MMM) extracted the data, which were checked by a second author. We contacted study authors for extra information and collected data on adverse effects from the trials. MAIN RESULTS: We did not find any large randomised or quasi-randomised trials of acetylcholinesterase inhibitors in generalised myasthenia gravis. One cross-over randomised trial using intranasal neostigmine in a total of 10 subjects was only available as an abstract. AUTHORS' CONCLUSIONS: Except for one small and inconclusive trial of intranasal neostigmine, no randomised controlled trial has been conducted on the use of acetylcholinesterase inhibitors in myasthenia gravis. Response to acetylcholinesterase inhibitors in observational studies is so clear that a randomised controlled trial depriving participants in the placebo arm of treatment would be difficult to justify. Sun, 24 Jul 2011 12:00:00 +0200http://www.institut-myologie.org/anglais/ewb_pages/n/news_5363.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5298.phpInduced pluripotent stem cells (iPSCs) have previously been derived from a number of other types of cells, including skin, stomach, liver, pancreas and brain cells. However, whether committed skeletal muscle stem cells and progenitor cells have the potency to undergo reprogramming to develop iPSCs in line with previously reported cases has still not established. This study led by Atsushi Asakura has demonstrated that induced pluripotent stem cells (iPSCs) that exhibit characteristics similar to those of embryonic stem cells (in that they can be coaxed into maturing, or differentiating, along various developmental pathways) can be derived from immature skeletal muscle cells called myoblasts. A possible advantage of deriving stem cells from myoblasts is that they may be more easily coaxed into becoming muscle cells than iPSCs derived from non-muscle tissues. The research team concluded that suppression of the MyoD gene is a necessary step in reprogramming myoblasts into iPSCs. They also highlighted that it would be advantageous to utilize the skeletal muscle system as a well-defined differentiation model to further elaborate on the effects of iPSC reprogramming in somatic cells. They hypothesised that myoblast-derived iPSCs may maintain epigenetic memory of myogenic status, which might contribute to the higher myogenic differentiation potential. Therefore, the use of myoblast-derived iPSCs will be a potential cell therapy for DMD.Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5298.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5297.phpImpairment of neuromuscular transmission can either be acquired or inherited. Congenital myasthenic syndromes (CMS) are due to gene mutations in proteins located in the presynaptic, synaptic, or postsynaptic part of the neuromuscular junction (NMJ). Neuromuscular junctions transmit impulses from motor neurons to skeletal muscle fibres leading to muscle contraction. Studying CMS can reveal fundamental mechanisms influencing development and function of the NMJ. Herein, researchers have demonstrated a link between neuromuscular transmission and the hexosamine biosynthetic pathway, which yields the amino sugar UDP-N-acetylglucosamine (UDPGlcNAc), an essential substrate for carbohydrate modifications of proteins and lipids. Using genetic linkage, they found 18 different biallelic mutations in the gene for the key enzyme of the hexosamine pathway, glutamine:fructose-6-phosphate amidotransferase 1 (GFAT1), in 13 unrelated CMS families. Moreover, GFAT1 down-regulation in zebrafish embryos altered muscle fibre morphology and impaired normal NMJ development. A so-far unrecognised involvement of GFAT1 and the hexosamine pathway in neuromuscular transmission was revealed, adding to existing concepts of the glycobiology of the NMJ. As the vertebrate NMJ is a classic model synapse, further investigation of the role of GFAT1 for NMJ function is likely to also contribute to the understanding of synapse development and organization in general. GFAT1 and the hexosamine pathways have been implicated in signalling pathways that may become deregulated in diseases of the immune system, diabetes mellitus, cancer, cardiovascular disease, and neurodegenerative diseases. These data provide additional incentive for investigating the role of GFAT1 in human health and disease. Clinicians can now order genetic tests to confirm mutations in the newly implicated gene, allowing for earlier confirmation of CMS diagnosis and subsequent treatment with cholinesterase inhibitors, which improve nerve-muscle signalling by increasing the effectiveness of the neurotransmitter acetylcholine.Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5297.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5296.phpOver the past several years, more focus has been placed on dissecting the genetic basis of complex diseases and traits through genome-wide association studies. In contrast, Mendelian disorders have received little attention mainly due to the lack of newer and more powerful methods to study these disorders. Linkage studies have previously been the main tool to elucidate the genetics of Mendelian disorders; however, extremely rare disorders or sporadic cases caused by de novo variants are not amendable to this study design. Exome sequencing has now become technically feasible and more cost-effective due to the recent advances in high-throughput sequence capture methods and next-generation sequencing technologies which have offered new opportunities for Mendelian disorder research. This method is capable of resequencing a nearly complete set of coding exons in an individual. To evaluate whole-exome sequencing for genetic diagnosis of more ubiquitous Mendelian diseases, Charcot-Marie Tooth (CMT), which comprises a large number of genetically distinct forms of inherited peripheral neuropathies, is an attractive model. In this study the authors have performed whole-exome sequencing in one individual of an undiagnosed family with CMT. They successfully applied the technique to identify the causative mutation and clinical characteristics had previously been reported. Their data confirm the paradigm shift towards genomic approaches for rapid gene identification. Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5296.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5295.phpOculopharyngodistal myopathy (OPDM) is an adult-onset muscle disorder with an autosomal dominant and autosomal recessive mode of inheritance. It is characterised by ptosis as initial symptom followed by slowly progressive dysphagia and muscle weakness in the hands and lower legs. Presently, 29 patients from 14 families with a compatible clinical phenotype have been described in 10 reports worldwide. The authors of the present study report the detailed clinical and molecular genetic findings from the largest series of 47 patients with OPDM from Turkey. Findings include: a slightly earlier age at onset compared to that reported in previous studies; the presence of autosomal and recessive inheritance patterns in the families but without any clear difference in clinical phenotype and severity; prominent facial muscle atrophy and prominent oropharyngeal dysphagia of myopathic origin. These data have allowed to refine the clinical phenotype of OPDM and to facilitate the identification of the genetic defect.Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5295.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5294.phpSix putative glycosyltransferase genes are currently known to cause congenital muscular dystrophy (CMD) associated with abnormal glycosylation of alpha-dystroglycan (áDG). The LARGE gene is the least common of these, with mutations reported previously in only one family. In this study led by Pascale Guicheney, the genetic basis of CMD in a consanguineous family with two children who had typical features of an alpha-dystroglycanopathy was determined. They performed a genome-wide microsatellite study, which demonstrated linkage to LARGE but gene sequencing from genomic DNA (gDNA) was normal. Sequencing LARGE from cDNA derived from patient lymphocytes showed an abnormal sequence inserted between exons 10 and 11. Most mRNA transcripts contained a 197 bp insertion but low levels of a 171 bp insertion and a normally spliced transcript were also seen. The abnormal sequences mapped to a spliced EST (DA935254) of unknown function, normally located 100 kb centromeric to LARGE on chromosome 22q. Both abnormal sequences are predicted to introduce a premature stop codon. Quantitative PCR analysis of the EST sequence showed twice the copy number in patient gDNA compared to controls, consistent with a duplication of this sequence. Quantitative PCR analysis for regions 5' and 3' of the EST showed the duplication involves between 30 and 57 kb of genomic DNA. LARGE splicing in muscle was not assessed due to lack of tissue but results from lymphocytes suggest that the patients may express low levels of normal enzyme. These data provide evidence for a duplication/insertion involving intron 10 of LARGE that causes an EST to be abnormally spliced into most LARGE mRNA transcripts, likely resulting in very low expression of normal protein.Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5294.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5293.phpCharcot Marie Tooth (CMT) disease, a hereditary peripheral neuropathy, is one of the most common inherited nerve-related disorders resulting in predominately distal lower and upper limb weakness and sensory loss. Mutations in more than 30 genes cause different forms of this disease and this presents a challenge for clinicians and patients. Not much information is available to help direct genetic testing. Yet family planning and prognosis often require an accurate genetic diagnosis. In this study, research scientists evaluated data from more than 1000 patients with CMT from their clinic (with known genetic testing results), to determine the percentage and features of each CMT subtype. Their analysis demonstrated that clinical and neurophysiologic information could be useful in focusing genetic testing for CMT. By characterising common phenotypes for particular forms of CMT, these data can also be helpful in determining whether a given patient is typical or unusual for a particular genotype. Based on the data obtained, the authors have developed a series of flow diagrams to direct future genetic testing performed in their clinic. This focused approach to CMT testing based on phenotype, physiology and prevalence is potentially useful to people caring for patients with inherited neuropathies.Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5293.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5292.phpDuchenne Muscular Dystrophy (DMD) is a slow progressive genetic disease that eventually results in the loss of ability to walk. Management of DMD involves a multi-disciplinary team approach; the aim of physical therapy management is to prevent contractures and maintain ambulation. Similarly, nutritional management is focused on preventing under-nutrition as well as obesity. Obesity affects more than half of 13-year-old boys with DMD and can exacerbate difficulties with locomotion. On the other hand, adolescents and adults with DMD frequently experience feeding difficulties and underweight, which can result in pressure sores and to a higher risk of lung infections. The present study used a longitudinal approach to assess the natural evolution of weight status in DMD patients. Body weight measurements for 70 DMD patients were collected retrospectively from medical files and the body weight: age ratio (W:A) was used to evaluate weight status in reference to the Griffiths and Edwards chart. The findings show that the change in body weight from 13 years of age to late adolescence differed between obese and normal weight 13 year old DMD boys. Obese boys remained obese for several years, at least until the age of 18.2 years, when their body weight plateaued then began to decline. These data imply that mild obesity at early adolescence (W/A between 120 and 150%) should not be discouraged because it may prevent underweight in late adolescence. Although respiratory and nutritional statuses are closely associated, the authors found no relationship between being underweight and respiratory alterations or between the beginning of respiratory support and improved weight status. Nevertheless, a negative correlation was observed between obesity and the need for respiratory support at the end of follow-up. These findings may help medical staff identify DMD patients needing dietary adaptation and intervention.This study was funded by the AFM.Tue, 01 Mar 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5292.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5289.phpSpinal Muscular Atrophy (SMA) is caused by recessive mutations in the survival of motor neuron (SMN) gene that leads to progressive muscle weakness in infants and children. SMA research has mainly focused on the neuromuscular synapse. The effects of SMA on motor neurons within the central nervous system have been relatively unexplored. To have a better understanding of the disease's impact on motor neurons within the central nervous system, which will in turn provide more rational targeting of therapeutic strategies, the authors of this study examined the time course of pathological changes in motor neurons and other neurons that communicate with them. To this end, the researchers used a common SMA mouse model to examine the 1a reflex, a simple, complete circuit that could be analysed in the isolated spinal cords. An entire neural circuit was examined by artificially stimulating the sensory input and measuring the output of all the motor neurons. The L1 nerves that infiltrate the muscles affected early in SMA were initially analysed. Malfunction was evident in spinal cords taken from mice as young as four days old. Circuits from the SMA mice produced only 15 percent of the peak amplitude of cords from wild-type mice. However, the motor neurons were fully capable of carrying a membrane potential. In fact, they were hyperexcitable compared to motor neurons from wild-type mice. Sensory neurons were another matter. When sensory cell axons that project toward motor neurons in the spinal cord were labelled, they were found to be shorter than normal. Furthermore, there were fewer synapses between the sensory and motor neurons in the SMA spinal circuits than in wild-type ones. These findings indicate that loss of sensory circuits precedes motor neuron loss, but it is not clear yet what starts the process. Since SMN is ubiquitous, any cell could suffer from its absence and set off a degenerative cascade. In order to determine whether symptoms begin in proximal muscles near the trunk and move into more distal areas the L1 circuit that innervates proximal muscles was compared with the L5 circuit, which controls distal muscles. In spinal cords from four-day-old animals, transmission in the L1 circuit was strikingly affected compared to wild-type cords. However, the L5 circuit activity was normal. But at the 13-day mark, both circuits from SMA mice were affected. Reductions in the motor neuron population followed the same trend. By four days, it was estimated that the L1 circuit had lost 65% of the normal number of sensory-motor synapses, and the percentage rose to 80% loss at 13 days. In contrast, the L5 synapse counts were normal at four days, but dropped by half at 13 days. The results suggest that pathology in the mouse begins in proximal circuits and later progresses to distal ones, nicely mirroring human symptoms. The study provides a thorough tour of SMA physiology, which should form a useful baseline for future research.Sun, 13 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5289.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5287.phpDilated cardiomyopathy (DCM), characterized by left ventricular dilatation and systolic dysfunction, constitutes a significant cause for heart failure, sudden cardiac death or need for heart transplantation. This report describes how researchers at the University of North Carolina at Chapel Hill School of Medicine have discovered a link between DCM and the lack of an enzyme produced by a gene called DOT1L (disruptor of telomeric silencing). In mice that were predisposed to DCM, the team found that the gene was absent. They report that cardiac-specific knockout of Dot1L results in increased mortality rate with chamber dilation, increased cardiomyocyte cell death, systolic dysfunction, and conduction abnormalities. These phenotypes mimic those exhibited in patients with dilated cardiomyopathy (DCM). The authors found that re-expression of a single downstream target gene, dystrophin, prevented the mice from developing DCM. If DOT1L levels fall too low, dystrophin ceases to perform its function, eventually leading to heart disease. These results have implications for patients with dilated cardiomyopathy and other conditions and may open new avenues for the diagnosis and treatment of human heart disease.Wed, 09 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5287.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5286.phpAdvances in surgical and medical therapies have allowed many children born with cardiomyopathy or other congenital heart defects to live longer but they may eventually succumb to heart failure. A recent study has generated important pre-clinical laboratory data showing that heart stem cells from children with congenital heart disease can be used to regenerate their damaged hearts. With this promising therapy option, these children may avoid the need for a heart transplant and may potentially live longer and have more productive lives. Cells were obtained from patients ranging in age from a few days after birth to 13 years who were undergoing routine congenital cardiac surgery. The data show that the number of heart stem cells was greatest in neonates and then rapidly decreased with age, and that the highest numbers of these stem cells are located in the right atrium. Furthermore, this report demonstrated that the cardiac stem cells are functional and have the potential for use in repairing the damaged heart. Up until now, heart stem cell studies have addressed the adult diseased heart, but this is the first and largest systematic study to focus on children.Wed, 09 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5286.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5285.phpGlaxoSmithKline (GSK) and Prosensa have begun treatment in the first patient in their Phase III clinical study investigating GSK2402968, in ambulant boys with Duchenne Muscular Dystrophy (DMD), who have a dystrophin gene mutation amenable to an exon 51 skip (up to 13% of boys with DMD). The initiation of this study is an important milestone as there is currently no approved treatment to alter the course of DMD. GSK968, an antisense oligonucleotide, which induces exon skipping of exon 51, is currently in late stage development for DMD. It has been designated orphan drug status in the EU and US, and is being developed as part of an alliance between GlaxoSmithKline and Prosensa. This randomised, placebo controlled study will enrol 180 patients, from up to 18 countries, and is currently the most advanced ongoing study for this rare, severely debilitating, neuromuscular disease. The study is designed to assess the efficacy and safety of GSK968 6mg/kg, once weekly, compared to placebo, for 48 weeks in ambulant boys over 5 years of age with DMD The primary efficacy endpoint is a measure of muscle function using the six-minute walking distance test.Wed, 09 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5285.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5284.phpNestin is a large intermediate filament protein (class Type VI) that is expressed predominantly in stem cells of the central nervous system in the neural tube. Nestin is expressed during development and in myotendinous and neuromuscular junctions. In this study, Salk Institute of Biological Studies investigators led by Dr. Kuo-Fen Lee, show that nestin regulates formation of the neuromuscular junction. This is the first study to show that nestin actually has a physiological function. The authors examined how cdk5 eliminates unnecessary extrasynaptic connections by reasoning that cdk5 must act by chemically modifying a second protein. After eliminating the obvious candidates, the team finally considered nestin, based on evidence that cdk5 can phosphorylate nestin in some tissues. To analyze nestin, the group used agrin knockout mice. As predicted, examination of diaphragm muscle tissue in these mice showed a complete loss of mature synapses. However, in agrin and nestin double knockout mice, surprisingly the pattern of receptor clusters on diaphragm muscle reappeared, reminiscent of synapses of a normal mouse. Additional experiments confirmed that nestin is expressed on the muscle side of the neuromuscular junction and that nestin phosphorylation is required for its novel function. This discovery will not only increase the understanding of signalling mechanisms connecting brain to muscle, but could aid future attempts to strengthen those connections in cases of neuromuscular disease or spinal cord injury and enhance development of tissue replacement therapies.Wed, 09 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5284.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5283.phpSpinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease and the most common genetic cause of infant mortality. The disease results in motor neuron loss and skeletal muscle atrophy. Spinal muscular atrophy is caused by mutations in the telomeric copy of the survival motor neuron 1 (SMN1) gene, but all patients retain a centromeric copy of the gene, SMN2. In the majority of cases, the disease severity correlates inversely with an increased SMN2 gene copy number. SMA is subdivided into three clinical types based on age at onset (SMA types I-III) and the highest level of motor function achieved. However, the genotype-phenotype correlation is incomplete and is therefore not useful in clinical practice. In this retrospective study, the investigators examined a group of 103 SMA patients with homozygous deletions of SMN1 to refine the genotype-phenotype correlation. Three additional criteria were studied: age at death (only in SMA type I patients); brainstem involvement; and loss of ambulation. Moreover, the correlation between SMN2 copynumber and ambulation loss in SMA type III patients was also studied. The authors aimed to determine whether these additional clinical criteria could improve the correlation between SMN2 copynumber and the described SMA severity. Their results show that there is a strong correlation between survival time and SMN2 copynumber. In 57% of the patients studied, brainstem involvement, which is of major prognostic importance, was observed. Survival of patients with brainstem involvement was significantly reduced in all three SMA type groups, compared with the other patients. Among the patients who were able to walk, ambulation conservation was associated with a higher number of SMN2 copies. But the age at which ambulation was lost was not correlated with the number of SMN2 copies. Overall, the results from this study suggest that SMN2 copynumber should also be taken into account in prognosis, in association with standard clinical criteria.Wed, 09 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5283.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5282.phpFacioscapulohumeral muscular dystrophy (FSHD) is a dominant muscular dystrophy likely caused by epigenetic changes that lead to up-regulation of myotoxic genes. DUX4 has recently emerged as a strong FSHD candidate gene due to its location in the D4Z4 repeat, elevated expression in FSHD myoblast cultures, and pro-apoptotic function in vitro. However, the in vivo effects of DUX4 over-expression have not been reported. Here, the authors describe the first in vivo evidence that DUX4 overexpression causes histological and functional deficits consistent with muscular dystrophy in two animal models, zebrafish and mice. In zebrafish, DUX4 expression produced body malformations, somite defects, and myofibre degeneration. In neonatal mice, AAV6-delivered DUX4 caused muscle atrophy and adipose tissue replacement of muscle. In adult mice, AAV6.DUX4 produced muscle degeneration and turnover, apoptosis, and weakness. Importantly, expression of structurally intact but functionally inactive DUX4 mutants eliminated toxicity, supporting that DUX4-associated phenotypes are related to DUX4 function and not simply to non-specific over-expression. The authors also report a novel finding that the proapoptotic effects of DUX4 are p53 dependent. Their data therefore support a mechanism for DUX4 promyopathic activity, which could also explain its general toxicity to most cells in which it is overexpressed. These in vivo data are in harmony with the hypothesis that DUX4 overexpression contributes to FSHD.Wed, 09 Feb 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5282.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5278.phpSpinal muscular atrophy (SMA) is an autosomal recessive disorder resulting in the loss of motor neurons. Patients with SMA lack the survival motor neuron (SMN) protein encoded by two highly homogenous genes, SMN1 and SMN2, which essentially differ by an single nucleotide in exon 7. As a result, the majority of the transcript from SMN2 lacks exon 7. According to clinical severity, SMA has been classified to three types, including type I, type II, and type III. Drugs capable of modifying the transcription pattern of SMN2 to increase the full-length of SMN mRNA expression and the amount of SMN protein may have therapeutic effects for SMA patients. Hydroxyurea (HU) is an effective therapeutic agent for patients with thalassemia and sickle cell disease, which has is well tolerated and has shown minimal toxicity in children. The authors of the present study have previously carried out a small scale 33 SMA patients randomized pilot trial to evaluate the effect of HU in SMA patients, in which they obtained promising preliminary data. To confirm these findings, the authors designed a 2-year randomized, double-blind, placebo-controlled treatment follow-up trial to study the efficacy and safety of HU to treat patients with Types II and III SMA. The results indicate that HU did not significantly affect motor function, strength, lung function, or serum flSMN mRNA in patients with type 2 and 3 SMA. Furthermore, a significant number of patients developed reversible neutropenia. This trial provides longitudinal observations of the natural evolution in type 2 and 3 SMA and further addresses the issue that standardization of clinical care for SMA should be considered just as important as pursuing potential agents for curing SMA. Further studies recruiting a larger SMA population with homogeneous disease severity and concomitantly measuring other potential biomarkers, e.g., SMN protein, may help to clarify the clinical efficacy of HU.Sun, 23 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5278.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5277.phpDuchenne muscular dystrophy (DMD) is a severe X-linked disease caused by mutations in the DMD gene that lead to nearly complete loss of dystrophin in skeletal and cardiac muscle. In this study, the authors show how a variant in the gene for the osteopontin protein has the potential to help predict disease course in DMD. Osteopontin is a cytokine that promotes immune cell migration and survival; high tissue and circulating levels of osteopontin have been identified in a variety of muscular dystrophies, various inflammatory disorders, and cancer. Osteopontin is believed to encourage tissue inflammation and fibrosis, which are considered harmful effects in DMD. It may also influence muscle remodelling, however, which would be helpful in DMD. The authors used informatics approaches, based on their earlier studies in normal subjects and from comparisons of rapid vs slow progression in DMD, to select a limited set of 29 candidate polymorphisms for analysis. One of the polymorphisms is a previously known single base variant in the promoter region of SPP1 (osteopontin). The authors provide evidence that this genetic modifier, the G allele of rs28357094 (observed in 35% of cases), is associated with more severe disease, as measured by either time to continuous wheelchair use or grip strength in 2 independent cohorts. The severe allele is present in about a third of all people, so this single allele could account for a substantial portion of the variability in disease progression. The presence of the G allele may provide a basis for stratifying patients entering clinical trials according to the anticipated rate of disease progression. This may improve the power of the trial by reducing interindividual heterogeneity, thereby permitting clinicians to select the relatively rapidly progressing subjects who may respond better to therapy. In addition, the SPP1 variants associated with disease severity in DMD suggest the possibility of osteopontin as a rational therapeutic target. Sun, 23 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5277.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5276.phpIn addition to mutations in dysferlin, LGMD2B and Miyoshi myopathy (MM) can have other genetic causes. Understanding the genetic basis and clinical course of these non-dysferlin LGMD2B/MM cases may accelerate understanding of the pathological process in dysferlinopathy. Recently, mutations in the ANO5 gene, which encodes a putative calcium-activated chloride channel belonging to the Anoctamin family of proteins, were identified in 5 families with one of two previously identified disorders, non-dysferlin Miyoshi muscular dystrophy (MMD3) and LGMD2L. This study reports on the largest cohort to date, of patients with ANO5 gene mutations. The results indicate that mutations in the ANO5 gene, in particular the common c.191dupA mutation, are responsible for a clinically recognizable adult onset LGMD, mainly involving the pelvic girdle and the proximal lower limbs, with high serum creatine kinase values. Upper limb muscle function is only mildly affected and cardiac and respiratory function is normal. Females appear less frequently affected. The common ANO5 mutation can also lead to a variable clinical presentation at onset, but the authors have shown here that with disease progression, the phenotypes largely overlap and merge into a more homogenous clinic entity. The mutation c.191dupA is frequent in the British and German LGMD cohorts, occurring in all 20 of the mutation positive patients, and was found to be in strong linkage disequilibrium with an intragenic single nucleotide polymorphism in exon 10 of ANO5, and an extragenic microsatellite marker 135 Kb downstream of the gene. It is therefore likely that the high frequency of the common mutation is the result of a founder effect. The authors suggest that mutation screening, particularly of the common mutation c.191dupA, should be an early step in the diagnostic testing of patients fitting this clinical description.A founder mutation in Anoctamin 5 is a major cause of limb-girdle muscular dystrophy.Sun, 23 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5276.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5275.phpMyotonic dystrophy type 1 (MD1) is an autosomal dominant multisystem disorder caused by an abnormal expansion of a trinucleotide cytosine-thymine-guanine (CTG) sequence found on chromosome 19. It affects skeletal, smooth and cardiac muscle causing nervous system abnormalities, ocular diseases and endocrine disorders. Cardiac involvement is an integral part of the disorder, and it is mainly represented by conduction abnormalities, arrhythmias and increased risk of sudden death. Less commonly, myocardial involvement due to DM1 can lead to left ventricular systolic dysfunction (LVSD) and clinical heart failure (HF). This study describes the prevalence and outcome of LVSD/ HF in patients with DM1. The data show that there is a significant overall prevalence (10.1%) of LVSD/HF in a large cohort of patients with genetically confirmed DM1. Increasing age, male sex, ECG conduction abnormalities, presence of atrial and ventricular arrhythmias, and implanted devices are all significantly associated with LVSD/HF, whereas CTG repeat length and MIRS score are not. Furthermore, LVSD/HF in patients with DM1 is associated with significantly increased risk of overall mortality, sudden death, and ventricular arrhythmias.Sun, 23 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5275.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5274.phpIt is well known that myostatin is a negative regulator of skeletal muscle mass and several approaches have been used to knockdown this factor to induce an increase in skeletal muscle growth. The use of antisense oligonucleotides (AOs) to induce exon skipping and thereby knockdown the expression of myostatin presents several advantages over the other currently used gene therapy approaches. Firstly, there is no risk of uncontrolled insertion into the genome with AOs as in case of virus-mediated approaches. Moreover, with an appropriate dosing regimen, exon skipping levels can be regulated and, if necessary the treatment can be interrupted. Importantly, AOs have not been reported to produce any toxic effects or immune response so far in animal models as well as when used in clinical application. The present study led by Professor George Dickson, demonstrates that AOs were able to inactivate myostatin in vitro and that substantial myostatin exon skipping was observed in vivo, leading to a significant increase in soleus muscle mass as compared to the controls. These data constitute a proof-of-principle that oligonucleotide-mediated antisense exon skipping leads to a physiologically significant blockage of myostatin activity in vitro and in vivo. This work has the potential to be developed into an efficient treatment for a number of age-related muscle disorders and various neuromuscular disorders, and along with dystrophin rescue or augmentation, to treat Duchenne muscular dystrophy. Sun, 23 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5274.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5268.phpDuchenne Muscular Dystrophy (DMD) is caused by mutations in the gene that encodes the protein dystrophin and the subsequent disruption of the dystrophin-associated protein complex (DAPC). The disease effects about one of every 3,500 boys whose muscle function is so degraded that they die usually before they reach the age of 30. Investigators at Brown University (Providence, RI, USA) explored the possibility of manipulating utrophin, a dystrophin homolog expressed at high levels in developing muscle, as a target for DMD therapy. In normal muscle cells, utrophin is located at the neuromuscular synapse and myotendinous junctions. It is necessary for normal membrane maintenance, and for the clustering of the acetylcholine receptor. In adult humans, utrophin RNA is found ubiquitously, being abundant in the brain, kidney, liver, lung, muscle, spleen, and stomach. In the human foetus during muscle differentiation, utrophin is found at the sarcolemma. It disappears when the foetus begins to express dystrophin. In this study, the research scientists revealed that the extracellular matrix protein biglycan regulated utrophin expression in immature muscle, and that recombinant human biglycan (rhBGN) increased utrophin expression in cultured myotubes. Systemically delivered rhBGN increased utrophin at the sarcolemma and reduced muscle injury in the mdx mouse model of DMD. RhBGN treatment also improved muscle function. RhBGN was well tolerated in animals dosed for as long as three months. The results of this study suggest that biglycan shows potential to slow muscle wasting and modify the progressive course of the disease and that simple injections may have a durable effect on muscle strength. Multiple lines of evidence make biglycan a compelling candidate for moving into human testing as soon as possible.Mon, 10 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5268.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5267.phpMyotonic dystrophy (DM1) is associated with excessive repetition of CTG triplets in the DMPK gene. The severity and age of onset is inversely proportional to the size of the CTG expansion. In this article, a team of Canadian researchers has characterized the length of CTG expansion and the methylation profile of the DM1 locus, of biopsies from DM1 foetuses and adults, healthy individuals or DM1 transgenic mice. In the DM1 foetus, the highest number of repetitions was observed in the heart and the lowest in the liver. In the DM1 adult with, the highest number was found in the heart and cerebral cortex, and the lowest in the cerebellum (a difference of up to over 5770 repetitions). Abnormal methylation is specific for the mutated allele. The heart, liver and cerebral cortex of the DM1 adult showed moderate to high methylation levels while the cerebellum, pancreas and skeletal muscle were devoid of methylation. Methylation is greater in the foetus than in adults. Contrary to what had previously been shown, it is not restricted to individuals with congenital DM1. In humans, CTG repetitions define a methylation boundary: the upstream sequences, including the CTCF binding site are methylated, whereas repetitions and downstream sequences are not. In the mouse model of DM1, the specific patterns of methylation depending on the number of repetitions, the tissue and age were found, although different from that observed in humans, since the sequences are methylated upstream and downstream of repetitions, with a higher upstream methylation. Thus, in humans, the expansion of CTG triplet repeats seems to maintain the methylation profile of the DM1 locus, which varies greatly depending on age and tissues.Mon, 10 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5267.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5266.phpResearchers have known for many years that Duchenne muscular dystrophy (DMD) is caused by a single mutation in the dystrophin gene. New findings by researchers at Stanford University School of Medicine suggest that disease symptoms, including progressive muscle weakening leading to respiratory failure, only begin when skeletal muscle stem cells can no longer keep up with the ongoing damage caused by the disease. The study results suggest that DMD is not just a disease of dystrophin deficiency but also a disease of stem cells; meaning that successful treatments would likely need to target muscle stem cells, not just muscle fibres. The new study also answers a long-standing puzzle in the field that has stymied basic studies in search of potential treatments or treatment strategies: Mice carrying the same dystrophin mutation found in human patients show only mild symptoms of the disease. The new findings attribute the discrepancy between the mouse and human symptoms to telomeres, which are longer in mice than they are in humans. The research team found that dystrophin deficient mice with shortened telomeres have severe symptoms of the disease that worsen with age, just as they do in human patients. Telomeres protect chromosomes from deterioration and they tend to get shorter each time a cell divides. When telomeres become critically shortened, it triggers events that lead to cell death. Mice with shorter telomeres show all the characteristics of the disease and the observed muscle weakening paralleled a decline in the regenerative capacity of their muscle stem cells. When the researchers isolated and transplanted healthy muscle stem cells into the sick mice, it alleviated symptoms of the disease. This new mouse model that mimics the human disease will benefit all in the field and is very exciting for patientsMon, 10 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5266.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5265.phpValosin-containing protein (VCP) gene mutations have been linked to some cases of inherited Amyotrophic Lateral Sclerosis (ALS), or Lou Gehrig's disease. Mutations in the VCP gene have previously been shown to cause inclusion-body myopathy associated with Paget's disease of bone and/or frontotemporal dementia (IBMPFD). Using a new and advanced exome sequencing technique, a multinational team of researchers has identified five mutations in the VCP gene and implicated them as molecular causes of some familial forms of ALS. The team studied four individuals representing four generations of an Italian family, each of whom had a confirmed diagnosis of ALS and in whom the genes commonly associated with ALS (SOD1, TDP43 and FUS) were ruled out as the cause of disease. They subsequently examined 210 ALS-affected individuals from unrelated families, as well as samples from 1,205 unaffected individuals who made up the control group, and found four additional VCP mutations present in approximately 1 percent to 2 percent of familial ALS cases. The recognition that mutations in VCP can cause ALS provides a unique opportunity to gain insight into the ALS disease process. Although the frequency of VCP mutations in familial ALS must be confirmed in independent testing, it appears comparable to that reported for TDP43 and FUS mutations, highlighting the relative significance of this gene as a cause of familial ALS. These findings provide key information and increase understanding of the ALS disease process. This knowledge is vital to determining the disease's molecular underpinnings and designing effective therapies to slow, and ultimately cure, ALS.Mon, 10 Jan 2011 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5265.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5262.phpProximal spinal muscular atrophies (SMA) are linked to a deficiency of the SMN protein encoded by the SMN1 gene. Patients with SMA do not have a functional SMN1 gene. They have at least one copy of SMN2, almost identical to SMN1, which has a splicing mutation that leads to the synthesis of a predominantly unstable SMN protein with truncated amino acids encoded by exon 7. Several studies have shown an increased expression of intact SMN2 transcripts (including exon 7) in vitro with salbutamol, a â2-adrenergic agonist. Two pilot studies have also highlighted an improvement in motor function with salbutamol. In this study, Dr. Tiziano and colleagues evaluated the molecular efficiency of salbutamol in vivo. They describe the results of trial in which 12 patients with SMA type II or III received oral treatment with salbutamol for 6 months. A significant and constant increase of intact SMN2 transcripts was demonstrated in white blood cells, with a response proportional to the number of SMN2 gene copies. These results support the fact that the number of SMN2 copies must be taken into consideration when setting up trials with salbutamol.Fri, 03 Dec 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5262.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5261.phpTitin is a very large protein, which plays a major role in the assembly, structure, elasticity and integrity of sarcomeres. It also helps stabilize calpain 3 from autolytic degradation. Mutations in the gene encoding titin induce several types of skeletal or cardiac myopathy. Tibial muscular dystrophy and limb girdle muscular dystrophy type 2J (LGMD2J) are related to a founder mutation in the C-terminal domain of the protein, which was described in a single large Finnish family, and named FINmaj. Furthermore, we know that the level of calpain 3 is decreased in patients with LGMD2J and tibial muscular dystrophy. To investigate the pathogenic mechanisms of LGMD2J and tibial muscular dystrophy, a team of French scientists from Genethon, generated a mouse model carrying the FINmaj mutation. The analysis of the phenotypes of heterozygous or homozygous mice was recently published. In heterozygous mice, the dystrophic phenotype appeared late, at 9 months of age, in a few distal muscles, whereas it appeared earlier (from the first month in the soleus muscle) and more severe (affecting most muscles at the age of 6 months) in homozygous mice. No cardiac problems were described for the heterozygous mice but the homozygous mice all exhibited a dilated cardiomyopathy. Embryonic lethality began from week 12 in heterozygous and homozygous mice. In this mouse model, the mutation causes the loss of the extremity of the C-terminal domain of titin and instability and a deficiency in calpain 3. Note that the titin mutation does not prevent it from being incorporated in the sarcomere. To better understand the role of calpain 3 in these two diseases, the authors crossed FINmaj mutant mice with mice deficient in calpain 3. The disease phenotype is corrected in mice with FINmaj and calpain 3 mutations, demonstrating the involvement of calpain 3 in the development of the disease related to a deficiency in titin. This could therefore represent a therapeutic strategy.This work was funded by the AFMFri, 03 Dec 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5261.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5259.phpInsulin-like growth factor 1 (IGF-1) regulates muscle differentiation and growth. However, in patients with myotonic dystrophy type 1 (DM1) the level of IGF-1 is reduced or low. Treatment with IGF-1 causes an increase in protein synthesis and differentiation of DM1 muscle cells in vitro. Furthermore, treatment with recombinant human IGF-1 complexed with the IGF-3 recombinant human (rhIGF-1/rhIGFBP-3) binding protein was shown to be efficacious in children with severe IGF-1 deficiency. In this article, a team of American researchers assessed the safety of treatment with rhIGF-1/rhIGFBP-3 in 15 ambulatory patients with DM1. Patients were divided into 2 groups that received increasing doses of rhIGF-1/rhIGFBP-3 for 24 weeks: the first group of 6 patients was treated with 0.5 mg/kg/day for 8 weeks then 1.0 mg/kg/day for 16 weeks; the second group of 9 patients received 0.5 mg/kg/day for 8 weeks then 1.0 mg/kg/day for 8 weeks and 2.0 mg/kg/day for 8 weeks. All patients were able to follow their treatment for 24 weeks (primary endpoint of the study). The treatment was associated with increased lean body mass (measured by X-ray biphotonic absorptiometry) and an improvement in metabolism, but no increase in muscle strength was observed. This pioneer study using two recombinant proteins showed that treatment with increasing doses of rhIGF-1/rhIGFBP-3 for 24 weeks is well tolerated in patients with DM1, without adverse reaction, even 16 weeks after treatment. These results should be confirmed in controlled trials against placebo and with a greater number of patients.Mon, 29 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5259.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5258.phpThe autosomal dominant form of centronuclear myopathy is linked to mutations in the DNM2 gene that encodes dynamin 2. Dynamin 2 is involved in endocytosis and membrane trafficking. However, the pathological mechanism associated with this mutation remains unknown. Herein, a team of French scientists has developed a mouse model expressing the most frequent human mutation of centronuclear myopathy, R465W. In mice heterozygous, the mutation induced a myopathy characterized by early impairment of muscle contraction (reduction in strength of the tibialis anterior muscle at 3 weeks). These events are associated with progressive muscular atrophy at 2 months of age and structural disorganization, particularly concerning the distribution of mitochondria and endoplasmic reticulum. According to the authors, muscle atrophy may be related to the activation of autophagy and proteasome signalling pathways. They observed an increased expression of genes involved in these mechanisms that progresses with age and that affects the quadriceps and gastrocnemius-plantar muscles at 8 months. Mice homozygous for the mutation die within the first 24 hours of life. The endocytic defect could be responsible for this lethality. Heterozygote fibres also showed an accumulation of dysferlin. Atypical retention of dysferlin could therefore be considered a new marker to guide the genetic test.Mon, 29 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5258.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5257.phpDysferlin is a large membrane protein, found in skeletal and cardiac muscle, monocytes, macrophages and the placenta. It plays a crucial role in the repair of cell membranes. When mutated or absent, dysferlin causes dysferlinopathies, such as limb girdle muscular dystrophy type 2B and Miyoshi myopathy. There is currently no treatment for these myopathies. Moreover, the transfer of the gene encoding dysferlin in adeno-associated virus is not viable for a gene therapy treatment, because of the huge size of the gene. This article describes the case of a patient with late-onset dysferlinopathy, with a naturally shorter and partially functional dysferlin (called “minidysferlin”). This shortened form therefore allowed the investigators to integrate the cDNA of this minidysferlin into an adeno-associated virus that they injected into dysferlin deficient mice. The human minidysferlin was strongly expressed in muscles of mice from the first month, demonstrating the stability of the protein produced, and it is correctly positioned at the sarcolemma. It also helps to efficiently repair the sarcolemma, the primary function of dysferlin, when the mouse muscle fibres are damaged. These results pave the way for new therapeutic strategies in dysferlinopathies.This work was funded by the AFMMon, 29 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5257.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5256.phpNG2 expressing glial cells (NG2+ cells) are the principal dividing cells in adult CNS. Although these progenitors are primarily restricted to an oligodendrocyte (OL) fate in the normal CNS, they have the capacity to differentiate into multiple cell types in vitro, including OLs, astrocytes and neurons upon exposure to different combinations of growth factors, suggesting that their environment can influence their fate. In neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), NG2+ cells increase their proliferation rate, indicating that pathologic changes within the spinal cord have a pronounced effect on the behaviour of these resident progenitors. However, the behaviour of NG2+ cells in the context of this disease has not been described quantitatively, and it is not known if the increase in proliferation is accompanied by alterations in their fate. In this article, a team of Johns Hopkins researchers analyzed changes in the behaviour of NG2+ cells during the course of disease in a mouse model of ALS (SOD1 G93A). The results revealed that NG2+ cells were the predominant proliferating cell type in ventral horn of spinal cord at disease onset, and this accelerated proliferation persisted until end stage. These changes in proliferation were accompanied by reactive changes in cell morphology. Green fluorescent protein (GFP) was used to monitor the fate of NG2+ cells in the spinal cord and showed that the number of GFP+ cells increased in ALS mice as compared to control during disease progression. When sacrificed at end stage, 46±4 % of GFP+ cells in ALS mice were immunopositive for an OL marker, whereas only 32 ±7% of GFP+ cells were positive for this marker in control mice, suggesting that NG2+ cells differentiate into oligodendrocytes at an accelerated rate in the diseased spinal cord. GFP+ cells did not immunolabel with markers for astrocytes, microglia (or neurons during the course of the disease. These results suggest that despite their increase in proliferation, NG2+ cells remain restricted to the oligodendrocyte lineage and do not contribute to the replacement of astrocytes or neurons in ALS.Mon, 29 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5256.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5255.phpFriedreich's ataxia (FA) is a progressive, autosomal recessive, multisystem degenerative disease ascribed to frataxin gene expansion. There is currently no effective treatment. FA has been shown to result from an iron-induced injury to the mitochondrial respiratory chain. Recent studies have suggested that lipid-soluble antioxidants lead to a modest reversal of cardiomyopathy in patients with FA. It is possible that antioxidants may also prevent the progression of neurodegeneration. In this paper Daniel Velasco-Sanchez and colleagues describe the results of an open-label clinical trial conducted in Spain involving 20 individuals with FA, aged 8 to 25 years old. Individuals received a combined treatment with the antioxidant idebenone and an iron-removal drug called deferiprone (DFP). Neurological evaluations were performed every six months using standardized measurements defined by the International Cooperative Ataxia Rating Scale (ICARS), which scores posture and gait, fine motor function, speech and eye-movement problems. Cardiac status was assessed through clinical evaluations, electrocardiograms and echocardiograms, which look at heart structure and performance. Magnetic resonance imaging (MRI) was used to measure iron levels in the brain. Stabilization in neurological function was observed, as the overall ICARS scores remained stable. Although posture and gait scores worsened, a significant improvement was observed in fine motor function. Data from echocardiogram testing showed improvement in several variables that measure cardiac hypertrophy, including a significant reduction in thickness of the septum. Analysis revealed significant reduction of iron levels in the brain. In addition, blood-iron level measurements were significantly decreased in all trial participants after the treatment period. Furthermore, side effects were mild and disappeared within two days following treatment. Further studies are needed to determine both the potential of and the most effective methods for using combined antioxidant/iron-chelation treatment.Mon, 29 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5255.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5254.phpFacioscapulohumeral dystrophy (FSHD) is an autosomal dominant muscular dystrophy. It has previously been shown that two genetic changes on chromosome 4, a contracted region of DNA in a region called D4Z4 and a “permissive” signal nearby that "opens" part of the DNA in D4Z4, were needed to cause FSHD. DUX4 is a protein that is normally active only during early development. In this paper, scientists have found that in the muscles and possibly in other tissues of people with FSHD, the DUX4 gene is mistakenly activated because of changes on chromosome 4, allowing some of this developmental protein to be produced. As such, FSHD represents the first human disease to be associated with the incomplete silencing of a gene that's normally expressed only during early development. It's The findings confirm and extend prior FSHD studies by analyzing a large number of muscle cells in vitro, from individuals with and without FSHD; studying RNA from muscle biopsy samples taken from individuals with and without FSHD; identifying a shortened form of DUX4 RNA in the muscle cells of individuals without FSHD and a full-length form of DUX4 RNA and full-length DUX4 protein in the muscle cells of people with FSHD; finding relatively high amounts of full-length DUX4 RNA in human testes and stem cells. These data provide a basis for explaining the molecular underpinnings of FSHD in the following way: i) normally, full-length DUX4 RNA is made from the D4Z4 region on chromosome 4 in stem or stem-like cells; ii) normally, in differentiated cells, DUX4 RNA expression from the D4Z4 region is, for the most part, repressed. Some DUX4 DNA escapes repression, allowing DUX4 RNA to be made, but in a shortened form, resulting in a shortened DUX4 protein; iii) in FSHD-affected cells, a contracted D4Z4 DNA region on chromosome 4 interferes with DUX4 gene silencing and also allows full-length, rather than short-form, DUX4 to be made when silencing is removed; iv) full-length DUX4, when produced after early development and in cells that are not stem cells, can cause damaging cellular changes. Short-form DUX4 protein does not appear to cause these. Strategies to block DUX4 either at the genetic level or the protein level could be developed. However, targeting such therapies precisely to the cells where DUX4 is being produced and precisely to DUX4 DNA, RNA or protein will no doubt pose many challenges.Mon, 29 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5254.phphttp://www.institut-myologie.org/anglais/ewb_pages/n/news_5236.phpAminoglycosides are antibiotics that disrupt protein synthesis by binding to ribosomes. They have the unique ability to suppress gene translation termination induced by premature stop codons, thereby allowing translation of the whole protein. In mdx mice, a reduction in serum creatine kinase as well as the full expression of dystrophin were observed after 14 days treatment with gentamicin. In this study, the effects of a long-term treatment with gentamicin were investigated. A first group comprising 10 DMD patients, with a stop codon in the gene encoding dystrophin, and a second group of 8 DMD patients, with a reading frameshift mutation, were treated with intravenous gentamicin (7,5 mg/kg) for 14 days. Serum creatine kinase level for subjects with a stop codon decreased by 50% and remained unchanged for subjects in the second group. Two other groups of 12 and 4 DMD patients with a stop codon in the dystrophin gene were treated with gentamicin for 6 months, respectively, 1 or 2 times a week. The group of 4 patients was originally to include 12 people, but 8 of them chose to participate in a protocol using oral treatment, which is easier to administer, PTC124. Therefore the results of both groups were then analyzed in one group of 14 subjects. Serum creatine kinase level was reduced and the level of dystrophin in the muscle biopsy was significantly increased. Muscle strength was stabilized and vital capacity increased slightly. No renal or hearing impairment was observed. In one patient, analysis of markers of the immune system showed signs of sensitivity to the newly formed dystrophin. Sun, 07 Nov 2010 11:00:00 +0100http://www.institut-myologie.org/anglais/ewb_pages/n/news_5236.php