In HCM, the causative genes most commonly involved are those encoding the cardiac β-myosin heavy chain (MYH7; thick filament), cardiac troponin T (TNNT2; thin filament) and cardiac myosin-binding protein C (MYBPC3; thick filament)5,8,11, (Fig. 1); disease-causing mutations have been detected in these three genes in South African families with AD patterns of inheritance.12-14 Parallel attempts to identify South African families segregating dilated cardiomyopathy (DCM) have not been successful to date (unpublished observation). The gene discussed is MYH7; the disease is dilated cardiomyopathy.