Medical conditions that run in a family are inherited or genetic—caused by changes in genes that are passed from generation to generation. Many different types of heart disease can be inherited.
Some conditions, like high blood pressure or coronary artery disease (blockages in the arteries that supply the heart with blood), run in families but probably result from a number of different genetic changes that individually have a subtle effect, but work collectively in a complex manner to cause disease.
There are other less common inherited heart diseases that are caused by just one or very few genetic changes that have a very strong effect in causing disease. Examples include conditions that affect the heart muscle, called inherited cardiomyopathies, such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). There are also inherited heart conditions that affect the electrical system of the heart, causing abnormal heart rhythms called arrhythmias. Examples of inherited arrhythmias include Long QT syndrome and Brugada syndrome. Some of these conditions may require changes in lifestyle or medical therapy. All inherited heart diseases require special attention not only for the individual patient but also for their family to see if other relatives are in need of medical care.
Secondary, or incidental, findings are genetic testing results of relevance for phenotypes or diseases beyond that which triggered the genetic test. (This contrasts with a primary genetic finding that explains disease in a patient tested after already being confirmed or suspected to have disease.) In most situations, the individual, when clinically evaluated, will have no evidence of the expected cardiovascular phenotype implicated by the variant identified by the specific genetic test. This has brought about a new dimension in clinical cardiovascular genetics: what to do with an individual identified with a putatively relevant (and usually disease-causing) variant with no phenotype.
