Dysferlinopathies: phenotypic study of a Moroccan series of 28 cases

Introduction Dysferlinopathies are a spectrum of autosomal recessive muscular dystrophies caused by mutations in the dysferlin gene (DYSF), leading to heterogeneous phenotypes, mainly limb-girdle muscular dystrophy type 2R (LGMDR2) and Miyoshi distal myopathy (MMD1). In Morocco, dysferlinopathies accounted for 18% of all limb-girdle muscular dystrophies, ranking second after sarcoglycanopathies. Methods We retrospectively analyzed 28 confirmed cases, diagnosed either by dysferlin deficiency or DYSF mutation. Results The median age at examination was 25,5 years (21-33). Twelve patients (43%) were female, and 19 (68%) had consanguineous parents. The proximodistal phenotype was predominant (50%), followed by LGMDR2 (39%) and MMD1 (11%). Selective biceps brachii involvement was observed in 68% of patients. Seven patients (25%) showed hypertrophy of the extensor digitorum brevis muscle, and two (7%) presented with severe genu recurvatum. In addition to dystrophic lesions, muscle biopsy revealed inflammatory infiltrates in 15 cases (58%), leading to an initial misdiagnosis of inflammatory myopathy in two cases. Dysferlin deficiency confirmed the diagnosis in 26 cases, while two others had homozygous DYSF variants. Four patients received corticosteroids, with clear improvement in only one. Overall, disease progression was slow, although two patients lost ambulation at the ages of 26 and 32. Regular physical activity appeared to have a beneficial effect in most patients.