An unusual family of benign "X" linked muscular dystrophy with cardiac involvement.

A family of benign X-linked muscular dystrophy is described. Two of the 3 affected members appear quite representative of Becker's dystrophy. A third shows no pseudohypertrophy, only gross atrophy, affecting proximal and distal muscles and also shows early onset contractures and electrocardiographic abnormalities and is in these ways much more representative of the variety described by Emery and Dreifuss (1966). Two of the cases have distinctly abnormal electrocardiograms with extensive and deep Q waves and abnormal R/S ratios and VI. Both these have shown progression of electrocardiographic abnormalities during a 2-year follow-up. The family is reported to document this very unusual occurrence.