Hypertrophic cardiomyopathy (HCM) is a primary cardiac muscle disorder with unique pathophysiology, heterogeneous expression, and diverse clinical presentations, with an overall mortality rate for untreated patients of approximately 1.3% per year. It is probably the most common genetically transmitted heart disease. HCM is often familial, of autosomal dominant transmission, and has a high degree of variable clinical penetrance. The latter is age related with typical features developing during adolescence. Approximately 50–70% of patients present mutations in one of the genes that encode different components of the cardiac sarcomere.