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Nonsyndromic dilated cardiomyopathy
Nonsyndromic dilated cardiomyopathy is a heart condition where the heart muscle becomes thin and enlarged, impairing its ability to pump blood effectively without affecting other parts of the body.
Overview
Dilated cardiomyopathy is a form of heart disease in which the heart becomes thin and enlarged (dilated), typically starting in the lower left chamber (left ventricle). It is classified as "nonsyndromic" when it cannot be explained by other causes like heart attacks or valve damage and is not associated with symptoms affecting other body systems.
Symptoms
Symptoms vary widely and can begin at any age, though they typically appear in mid-adulthood. They include:
- Palpitations (a sensation of fluttering or pounding in the chest).
- Shortness of breath, especially during physical activity or when lying down.
- Fatigue.
- Swelling of the legs and feet.
- Dizziness or fainting (syncope).
Over time, individuals may develop life-threatening complications, including abnormal heart rhythms (arrhythmias) and heart failure.
Causes
Variants in more than 20 genes have been linked to the condition. These genes provide instructions for proteins in cardiac muscle cells called cardiomyocytes. Many of these proteins are essential for muscle contraction through structures called sarcomeres or by forming the structural framework (cytoskeleton) of the cells. A notable example is the TTN gene, which provides instructions for the protein titin; variants in this gene account for 15 to 20 percent of all cases.
Inheritance
Nonsyndromic dilated cardiomyopathy is usually inherited in an autosomal dominant pattern, where one copy of an altered gene is sufficient to cause the disorder. However, it can also be inherited in an autosomal recessive pattern. Some cases result from new (de novo) variants that occur during the formation of reproductive cells or early embryonic development.