MMA is described most frequently in Asia, with studies of a few hundred individuals emerging from Japan, China and India; it is much less commonly seen in North America and Europe. The disease (disorder) was first described by Keizo Hirayama in 1959 as "juvenile muscular atrophy of unilateral upper extremity". In 1984 Mandavilli Gourie-Devi (et al) introduced the term<unk> ”. The disease primarily (but not exclusively) affects young (15- to 25-year-old) males. As of 2014 there had been less than 1500 described cases, starting with the patients in Hirayama's 1959 study. The condition is disproportionately high in Asia but no conclusive reason has been found for this. To date the largest studies recorded are Japan (333 cases), India (279 cases), and China (179 cases).
Monomelic amyotrophy
Congenital distal spinal muscular atrophy
Chondrodystrophy
Spinal muscular atrophy with lower extremity predominance 1
Hereditary neuralgic amyotrophy
Spinal muscular atrophy
Congenital muscular dystrophy
Spinal and bulbar muscular atrophy