Familial hypertrophic cardiomyopathy (FHCM) is a primary disorder of the cardiac myocytes that is characterized by left ventricular hypertrophy (thickening of the ventricle wall and/or interventricular septum), in the absence of another cardiac condition or systemic disease capable of producing significant hypertrophy. It is the most common inherited cardiac disorder, affecting 1 in 500 adults. The clinical expression of FHCM is highly variable, ranging from a complete absence of clinical symptoms to a severe form with a high risk of early death. Symptoms include fatigue, chest pain, shortness of breath, palpitations, syncope (fainting), and/or heart failure. The age at disease onset is typically in late adolescence or adulthood, although onset as early as the neonatal period has been reported. The genes that cause FHCM all encode components of the cardiac sarcomere:
myosin-bi