A family of Becker's progressive muscular dystrophy with severe cardiomyopathy.

A family of Becker's muscular dystrophy with marked cardiomyopathy was studied. The propositus, a 16-year-old boy with marked pseudohypertrophy in calves, showed electrocardiographic abnormalities resembling those in the Duchenne's type. Radionuclide study and endomyocardial biopsy revealed remarkable degeneration of myocardium. His uncle, who also had slight proximal muscular atrophy and weakness, and calves' pseudohypertrophy, died of heart failure at the age of 47, and autopsy showed dystrophic changes in skeletal muscles and extensive myocardial damage. Severe cardiac involvement can occur in Becker's muscular dystrophy which has been known to have an essentially benign clinical course, and radionuclide investigation is useful for the detection of preclinical cardiac lesions in patients with muscular dystrophy.