From OMIMMiyoshi muscular dystrophy (MMD) is an autosomal recessive skeletal muscle disorder characterized by onset in young adulthood of distal muscle weakness affecting the upper and lower limbs but sparing the intrinsic hand muscles. Muscle weakness and atrophy particularly affects the gastrocnemius and soleus muscles, and can later spread to involve the thigh and gluteal muscles. Patients showed impaired tiptoe standing, difficulty in climbing stairs, and difficulty walking, but usually remain ambulatory. Serum creatine kinase is increased and muscle biopsies show myopathic and dystrophic changes with necrosis (summary by Miyoshi et al., 1986).
Genetic Heterogeneity of Miyoshi Muscular Dystrophy
Miyoshi muscular dystrophy is a genetically heterogeneous disorder: MMD2 (613318) has been mapped to chromosome 10p, and MMD3 (613319) is caused by mutation in the ANO5 gene (608662) on chromosome 11p14.
See also Welander myopathy (604454), an autosomal dominant form of late-onset distal myopathy.
http://www.omim.org/entry/254130 From MedlinePlus GeneticsAs Miyoshi myopathy slowly worsens, the muscle weakness and atrophy spread up the leg to the muscles in the thigh and buttock and can also involve the upper arm and shoulder muscles. Eventually, affected individuals may have difficulty climbing stairs or walking for an extended period of time. Some people with Miyoshi myopathy may eventually need wheelchair assistance.
Rarely, abnormal heart rhythms (arrhythmias) have developed in people with Miyoshi myopathy. Individuals with Miyoshi myopathy have highly elevated levels of an enzyme called creatine kinase (CK) in their blood, which often indicates muscle disease.
Miyoshi myopathy is a muscle disorder that begins with weakness in the muscles that are located away from the center of the body (distal muscles), such as those in the legs. During early to mid-adulthood, affected individuals typically begin to experience muscle weakness and wasting (atrophy) in one or both calves. If only one leg is affected, the calves appear different in size (asymmetrical). Calf weakness can make it difficult to stand on tiptoe.
https://medlineplus.gov/genetics/condition/miyoshi-myopathy