In humans, dystrophin diseases are caused by mutations in the DMD gene and include the allelic phenotypes of Duchenne muscular dystrophy (DMD) [OMIM:310200], Becker muscular dystrophy (BMD) [OMIM:300376] and X-linked dilative cardiomyopathy (XLDCM) [OMIM:302045] [1-3]. The gene discussed is DMD; the disease is Becker muscular dystrophy.