First Japanese case of muscular dystrophy caused by a mutation in the anoctamin 5 gene

Mutations in the anoctamin 5 gene cause either limb girdle muscular dystrophy or Miyoshi muscular dystrophy 3 in Caucasians. We herein describe a 49-year-old Japanese man with asymmetry of the leg circumference since childhood. Muscle involvement began at the calf muscles, and later spread to the thigh and paraspinal muscles on imaging and physical examination. His external genitalia were morphologically hypoplastic. Genetic analysis identified a novel homozygous mutation, c.1178G>A (p.Trp393X), in the anoctamin 5 gene. This is the first Japanese case with Miyoshi muscular dystrophy 3 caused by an anoctamin 5 gene mutation (anoctaminopathy). The muscle impairment associated with Miyoshi muscular dystrophy 3 appears to spread from the distal to proximal lower extremities.