Congenital myopathies are a very heterogeneous group of neuromuscular diseases, classically characterised by their very early onset and a lack of symptomatic progression. Among them, myotubular myopathy is distinguished by its poor prognosis but also by the encouraging prospects brought by gene therapy in the canine model of the disease and the start of a clinical trial in humans.
Inherited as an X-linked recessive condition, it results in major hypotonia as well as ventilation and swallowing disorders that lead to an early death, with some exceptions. Numerous mutations of the MTM1 gene are involved.
Here, French researchers looked at the symptoms presented by females with myotubular myopathy. An analysis of clinical, genetic and histopathological data was performed in seventeen new cases. Together with twenty-six previously reported cases, the analysis highlighted a wide spectrum of phenotypes. With the exception of rare cases with very early detection, the most frequently encountered picture was that of a slowly progressive muscular deficit, with or without ophthalmoplegia, and very often asymmetrical. Asymmetry of growth was also noted. The authors estimate that in the absence of family history, the diagnosis remains difficult. The presence of centralised nuclei or necklace fibres on the muscle biopsy, and especially the more systematic study of the MTM1 gene using next generation sequencing techniques (NGS) will address the frequently reported diagnostic error.
