Many cardiac disorders can be inherited, including arrhythmias, congenital heart disease, cardiomyopathy, and high blood cholesterol.
Genetic traits that run in families can influence the risk for heart disease in many ways. Genes control every aspect of the cardiovascular system, from the strength of the blood vessels to the way cells in the heart communicate. A change, known as a genetic variant or mutation, in a single gene can affect the likelihood of developing heart disease. For example, a genetic variant can change the way the body processes cholesterol, increasing the likelihood of blocked arteries. These genetic variations are passed from parents to children in the DNA of the eggs and sperm. The parents' genetic code is then copied into every cell of a child's body during development.
When a family member is diagnosed with heart disease or a heart disorder, other family members are encouraged to undergo screening for risk factors and early stage disease that may not yet produce symptoms.
Inherited conditions that lead to arrhythmias and sudden cardiac death are particularly well understood. Some of these include:
- Long QT Syndrome: a genetic condition in which the heart takes longer than normal to recover electrically between beats (prolonged QT interval), increasing the risk of dangerous fast heart rhythms.
- Short QT Syndrome: a rare inherited condition where the heart’s electrical recovery phase is abnormally short (shortened QT interval), also increasing the risk of dangerous heart rhythms.
- Brugada Syndrome: a genetic condition affecting electrical signaling in the lower chambers of the heart (the ventricles). The heart structure is usually normal, and symptoms may be absent until a serious event occurs.
- Catecholaminergic polymorphic ventricular tachycardia: A disorder of calcium handling within heart muscle cells. Heart rhythm is usually normal at rest, but physical activity or emotional stress can trigger dangerous ventricular arrhythmias, leading to fainting or cardiac arrest
- Hypertrophic cardiomyopathy: a condition in which the heart muscle becomes abnormally thick, which can increase the risk of arrhythmia.
- Arrhythmogenic cardiomyopathy (including arrhythmogenic right ventricular cardiomyopathy): an inherited condition in which normal heart muscle is gradually replaced by fatty or scar tissue, disrupting electrical signalling and increasing the risk of ventricular arrhythmias.