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. It is caused by variations in the DYSF gene. Inheritance is autosomal recessive. Diagnosis may be confirmed by blood tests results showing an elevation of the creatine kinase (CK) and genetic testing. Miyoshi myopathy is part of the group of diseases known as "Dysferlinopathies", which are caused by different genetic changes in the DYSF gene.