The limb girdle muscular dystrophies (LGMD) are a group of at least 19 conditions affecting mainly the muscles around the shoulders and hips. LGMD2L patients generally start to experience symptoms in adulthood, including weakness and wasting of the shoulder, hip and thigh muscles. Miyoshi myopathy type MMD3 (also known as non-dysferlin Miyoshi myopathy) symptoms also emerge in adulthood. Initial symptoms can include calf weakness and wasting, along with difficulty in walking on tiptoes. As the condition progresses the shoulder, hip and thigh muscles may also start to weaken. Recent research has led to the identification of a gene that causes limb girdle muscular dystrophy type 2L (LGMD2L) and Miyoshi myopathy type (MMD3). In this multinational collaborative study, researchers examined DNA from French-Canadian, Finnish and Dutch families with either of these two conditions. They have identified specific mutations in the anoctamin 5 (ANO5) gene on chromosome 11 that can cause LGMD2L and MMD3: two ANO5 mutations that cause LGMD2L, two that cause type 3 Miyoshi myopathy, and one that can cause either disease. These muscular dystrophies have now been called the ‘anoctaminopathies’. The authors suggest that the ANO5 protein functions as a so-called calcium-activated chloride channel. The newly identified mutations may result in malfunctions in this channel, leading to a disruption of the repair process in muscle-fiber membranes. Although there is no immediate potential for treatment from the new findings, further characterization of ANO5 may result in a broader base of knowledge that could prove helpful in the study of LGMD, Miyoshi myopathy and possibly other muscle diseases. This information will help researchers to pursue the development of therapies.


Références : Recessive Mutations in the Putative Calcium-Activated Chloride Channel Anoctamin 5 Cause Proximal LGMD2L and Distal MMD3 Muscular Dystrophies.
Am J Hum Genet. 2010 Feb 12;86(2):213-221. Epub 2010 Jan 21.