Genetic diseases of the heart are those that are caused by a mutation in one or more genes that affect the structure or function of the heart muscle. Many of these diseases are rare, inherited only when one or both parents pass down the affected gene. Some of these conditions are especially common in certain communities or cultures where the populations are relatively isolated.

Arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia is a genetic disease in which normal heart tissue is progressively replaced with fat and scar tissue. According to St. Lukes-Roosevelt Hospital Center, tissue damage occurs predominantly in the right chamber of the heart 1. People who inherit this genetic disease may develop arrhythmias, or abnormal heart rhythms. Arrhythmogenic right ventricular dysplasia is a known cause of sudden death from cardiac arrest in people younger than 30. The condition is especially prevalent in communities in northeast Italy.

Brugada Syndrome

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Brugada syndrome is a life-threatening, frequently inherited disorder characterized by an abnormal heart rhythm, called a Brugada sign, according to the Mayo Clinic 3. This arrhythmia prevents the chambers of the heart from pumping effectively, preventing blood from traveling normally throughout the body. As a result, fainting or sudden heart attack leading to death can occur.

Familial Dilated Cardiomyopathy

Dilated cardiomyopathy is a condition in which the heart’s left ventricle becomes enlarged and weak, reducing the heart’s ability to pump blood. Over time, the disorder can damage multiple organs and lead to congestive heart failure. According to the Cleveland Clinic, about one-third of patients with dilated cardiomyopathy have an inherited form called familial dilated cardiomyopathy. Familial dilated cardiomyopathy is autosomal dominant, meaning you need only to get the abnormal gene from one parent in order to inherit the condition.

Long QT Syndrome

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Congenital long QT syndrome occurs in approximately 1 in 7,000 to 10,000 people in the United States, according to St. Lukes-Roosevelt Hospital Center 1. This condition is the result of gene mutations that lead to abnormal heart rhythms. A form of Long QT syndrome called Ward-Romano syndrome leads to abnormal electrical conduction in the heart that can cause fainting and sudden death, according to the Howard Hughes Medical Institute 2.

Ellis-van Creveld Syndrome

Ellis-van Creveld syndrome is a rare genetic condition commonly found among Amish people. In addition to short-limb dwarfism and other physical abnormalities, this syndrome causes a defect between the heart’s two upper chambers, or atria. These defects--known as atrial septal defects--can lead to shortness of breath, respiratory infections or arrhythmias, according to the Howard Hughes Medical Institute 2. Serious defects can lead to eventual heart failure.

Other Rare Genetic Diseases

Holt-Orams syndrome is a genetic disorder affecting approximately 1 in 100,000 individuals, according to the National Institutes of Health. The condition causes life-threatening heart defects and abnormally developed bones in the upper limbs. The most common defect seen in those with Holt-Orams syndrome is a hole in the septum between the atria. Some people may develop a hole in the septum between the lower heart chambers. In other cases, cardiac conduction disease can occur, causing a slower-than-normal heart beat called bradycardia or a rapid, uncoordinated heart contraction called fibrillation.

Marfan Syndrome is an inherited disorder of the connective tissue that affects roughly 1 in 5,000 people, according to the National Institutes of Health. It can cause structural heart abnormalities that lead to arrhythmias, palpitations, shortness of breath and fatigue. A weakening and stretching of the aorta can lead to life-threatening complications, including a bulge in a blood vessel wall called an aneurysm or a tearing of the the wall of the aorta.

Familial hypertrophic cardiomyopathy is a complex heart disease that may be caused by one of 900 known mutations on 12 different genes, according to the National Institutes of Health. The condition causes a thickening of the heart muscle wall. While it may cause no symptoms in some people, it can lead to fainting, chest pain, shortness of breath or--in rare cases--sudden death.