**2. Hypertrophic cardiomyopathy**

Hypertrophic cardiomyopathy (HCM) is a familial disease that in fifty percent of the cases is inherited in an autosomal dominant pattern. The disorder shows complete penetrance in most families although it depends on the age and the sex of the patients (Nimura, 1998, Richard, 2003, Richard, 2006).

As the prevalence of HCM is 1: 500, it can be stated that HCM is undoubtedly the most common cardiovascular disorder (Maron, 2002).

HCM has been traditionally described as an unexplained hypertrophy of the left ventricle that develops in the absence of systemic hypertension, valvular heart disease or amyloidosis. The left ventricular hypertrophy (LVH) is usually asymmetric and involves the septum.

The clinical presentation is variable. There can be varying degrees of clinical severity which can range from dyspnea, palpitations, atrial fibrillation, and syncopal episodes to congestive heart failure and sudden death. Many can be asymptomatic throughout their whole life, whereas others may even require heart transplantation. It is the most common cause of death in young athletes while practicing sports.

HCM generally has normal systolic function, impaired diastolic function and outflow ob‐ struction in about 25%. The histopathology shows myocyte disarray, interstitial fibrosis and hypertrophy (Richard, 2006, Ho, 2007).

Mutations in any of the thirteen sarcomeric genes lead to HCM. (See Table 1). The sarcomere has a complex structure where the proteins that form it interact among themselves. The different mechanisms that cause HCM are not yet completely understood. Most mutations in HCM are private of each family and there is clinical heterogeneity within family members (Richard, 2006 Hayashi, 2004; Frank, 2011).
