This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Miyoshi myopathy is a type of muscular dystrophy characterized by muscle weakness and atrophy (wasting), mainly in the distal parts of the legs. The first symptoms typically begin in young adulthood (on average 20 years of age) and include weakness and atrophy of the calves (sometimes asymmetrically), leading to inability to jump, run or walk on tiptoes. Over a period of years, the weakness and atrophy typically spread to the thighs and gluteal muscles. The forearms may become mildly atrophic with decrease in grip strength. Blood exams show an elevation of the creatine kinase (CK) often 10-100 times above the normal values. It is caused by variations (mutations) in the DYSF gene. Inheritance is autosomal recessive. Management may include physical therapy, use of mechanical aids, surgical intervention for orthopedic complications, respiratory aids, and social and emotional support.
Miyoshi myopathy is part of the group of diseases known as “Dysferlinopathies“, which are caused by DYSF pathogenic variants.
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