Disease-modifying mutations in familial hypertrophic cardiomyopathy: complexity from simplicity.

Cardiomyopathies are primary disorders of cardiac muscle associated with abnormalities of cardiac wall thickness, chamber size, contraction, relaxation, conduction, and rhythm. They are a major cause of morbidity and mortality at all ages and, like acquired forms of cardiovascular disease, frequently progress into heart failure.1 In contrast to dilated cardiomyopathy (DCM), which is characterized by left or biventricular dilation in association with depressed myocardial contractility,1 familial hypertrophic cardiomyopathy (FHC) is characterized by increased cardiac mass with myocyte and myofibrillar disarray. The disease is associated with electrical instability (ie, atrial and ventricular arrhythmias), which makes it the leading cause of death in young athletes. There is marked diversity in the morphological features and clinical manifestations of both DCM and FHC.2