If an immediate family member, such as a parent, sibling, or child, has hypertrophic cardiomyopathy - a disease in which the muscle of the lower left chamber of the heart (the left ventricle) becomes abnormally thick and enlarged - you should speak with a cardiologist about being screened for the disease. Because an HCM patient will sometimes have no symptoms but may suddenly experience cardiac arrest, even those without symptoms need to be followed up regularly to assess their risks for sudden death and to consider preventive treatments.
It is becoming increasingly clear that the most common type of HCM is caused by genetic abnormalities that affect the structural components of heart muscle and the way that the heart muscle is regulated at the molecular level. Currently, about 75 percent of patients with HCM have an identifiable genetic mutation that can be screened with a simple blood test. Once a defective abnormality is known, screening other family members becomes much easier. Importantly, if you have HCM, there is a 50 percent chance that other first-degree relatives also have it, whether or not they know it.