Miyoshi myopathy: diagnosis of a familial case of dysferlinopathy

Abstract

Miyoshi myopathy (MM) is a rare distal form of limb-girdle muscular dystrophies characterized by weakness primarily affecting the calves in adolescence or young adulthood, with slow progression, the ascending pattern of involvement of muscle groups in an atrophic process, and with obvious clinical polymorphism at onset (3 allelic variants are described). In MM, hypercreatine phosphatemia is noted to be 20– 50 times the normal blood concentrations. MM is referred to the dysferlinopathies with different mutations in the DYSF gene. In that manuscript we describe a 20-year familial case of 2 brothers with MM, including changes in their clinical manifestations, biochemical, CT and EMG parameters. The diagnosis was verified by whole exome sequencing of the DYSF gene to identify a homozygous missense mutations (c. 5302C>T) leading to replacement in the polypeptide chain of DYSF p.Arg1768Trp. The differential diagnosis of MM with clinically similar hereditary neuromuscular diseases is discussed.