Cardiac involvement in a family with Becker muscular dystrophy.

We report a family with Becker muscular dystrophy (BMD) presenting with cardiac involvement. The proband was a 41-year-old Japanese man who was hospitalized with exertional dyspnea and muscle weakness. Cardiac examination showed findings consistent with dilated cardiomyopathy. Dystrophin immunohistochemical analysis showed a discontinuous patchy staining pattern in cardiac and skeletal muscles biopsied from the proband. His brothers had high creatine kinase (CK) activity and abnormal electrocardiogram. Dystrophin gene analysis revealed that the proband and his brothers had G-to-T transversion at the terminal nucleotide of exon13. We conclude that the mutated dystrophin gene may cause cardiac involvement as a symptom precedent to skeletal muscle involvement.