Congenital myopathies are a very heterogeneous group of neuromuscular diseases. Despite the early onset of symptoms and stable course that they have in common, their clinical expression is highly variable. The number of genes involved (whether dominant or recessive) continues to increase. The nosological frameworks of this vast set of pathologies were based on the presence, not always specific, of elementary lesions visible under the optical and/or ultrastructural (cores, rods, central nuclei…) microscope.
In this article, an international consortium of researchers described a recent discovery associating centronuclear lesions and mutations of the RYR1 gene, the latter coding for a ryanodine receptor. The RYR1 gene has historically been associated with malignant hyperthermia and central coronary myopathy. In the present case, these were autosomal recessive forms (a very unusual mode of transmission for RYR1), which were described in 21 patients belonging to 18 families and presenting great variability in the clinical and histological expression of the disease. The abnormal positioning of the nuclei was often associated with myofibrillar disorganisation. The mutations found were never homozygous. Therefore, the RYR1 gene has now been added to the list of genes responsible for centronuclear myopathy, such as the MTM1, BIN1, CCDC78, DNM2 and SPEG genes.
