"Quadriceps myopathy": a clinical variant form of Becker muscular dystrophy.

A 26-year-old male with "quadriceps myopathy" is presented. He had a family history and only the bilateral quadriceps were wasted, without symptomatic weakness. The specimen of the muscle biopsy showed typical myopathic features without inflammatory reactions. The patchy defect of muscular dystrophin was proved by immunohistochemical study. Dystrophin analysis revealed abnormal 380 kDa dystrophin. Gene deletion was proved at exon 45-48 of Xp21 without frameshift. This case was considered to be a clinical variant form of Becker muscular dystrophy.