RESUMO
Dysferlinopathies encompass a large variety of neuromuscular diseases characterized by the absence of dysferlin in skeletal muscle and an autosomal recessive mode of inheritance. So far, three main phenotypes have been reported: Miyoshi myopathy (MM), limb girdle muscular dystrophy type 2B (LGMD 2B), and distal myopathy with anterior tibial onset (DMAT). A growing number of clinical variants have recently been described with a much wider range of symptoms and onset. Although rare, dysferlinopathies can account for up to 30% of progressive recessive muscular dystrophies in certain geographical areas, notably in the Middle East and the Indian subcontinent. Dysferlin is a large protein involved in membrane repair and vesicle trafficking and interacts probably with important immunological pathways. New insights in its pathophysiology may result in innovative therapies in the near future.
RESUMO
Long-term observations over a period of 22 years in an Indian family with primary dysferlinopathy are recorded, defining phenotypic variability. In the propositus, the dystrophy began distally in the tibialis anterior muscles, before involving the gastrocnemius. Transient painful calf hypertrophy, followed by calf wasting was observed. The proximal lower and upper limbs weakened after three to four years. The younger sibling presented with the proximo-distal phenotype. Both patients showed very high creatine kinase values early into the illness. Disease progression was slow. The younger sibling lost ambulation 14 years after onset, while the elder one remains ambulatory 22 years into the illness. Muscle biopsy showed dystrophic features and absence of dysferlin. Monocyte western blotting confirmed absence of dysferlin. Genetic analysis detected a heterozygous mutation in Exon 54 [c.6124C>T] in the DYSF gene. This is the first family with a diagnosis of dysferlinopathy supported by genetic data, reported from India.