Miyoshi myopathy; late-onset distal muscular dystrophy; distal myopathy, Nonaka type
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Introduction
form of muscular dystrophy
Pathology
- muscular dystrophy
- concentric lamellar bodies & acid phosphatase positive rimmed vacuoles seen on muscle biopsy
Genetics
- autosomal recessive
- associated with mutations in gene for dysferlin
Clinical manifestations
- muscle weakness that initially affects the gastrocnemius during early adulthood
- predilection for distal lower limb musculature
- hand & foot muscles relatively spared
- otherwise the phenotype overlaps with LGMD2B, especially in age at onset & creatine kinase elevation
Laboratory
- serum creatine kinase: mildly elevated
- dysferlin in leukocytes (defective, may or may not be present)