Familial isolated dilated cardiomyopathy

Familial isolated dilated cardiomyopathy (DCM) is a genetic form of heart muscle disease in which the left ventricle (or both ventricles) of the heart becomes enlarged (dilated) and weakened, reducing the heart's ability to pump blood effectively. Unlike dilated cardiomyopathy caused by infections, toxins, or other acquired factors, this condition runs in families and occurs without other associated syndromic features. It is estimated that 20–50% of all dilated cardiomyopathy cases have a genetic basis. The disease primarily affects the cardiovascular system and can lead to progressive heart failure, arrhythmias (abnormal heart rhythms), thromboembolic events (blood clots), and in severe cases, sudden cardiac death. Key symptoms include shortness of breath (dyspnea), fatigue, exercise intolerance, peripheral edema (swelling of the legs and ankles), palpitations, and syncope (fainting). Some individuals may remain asymptomatic for years before the disease is detected, often through family screening. The severity and age of onset can vary considerably, even within the same family, reflecting the genetic heterogeneity of the condition. Familial isolated dilated cardiomyopathy is genetically heterogeneous, with pathogenic variants identified in over 40 genes. The most commonly implicated genes include TTN (encoding titin), LMNA (lamin A/C), MYH7 (beta-myosin heavy chain), TNNT2 (cardiac troponin T), and SCN5A (sodium channel). Treatment follows standard heart failure management guidelines and includes ACE inhibitors or angiotensin receptor blockers, beta-blockers, diuretics, mineralocorticoid receptor antagonists, and newer agents such as sacubitril/valsartan and SGLT2 inhibitors. Implantable cardioverter-defibrillators (ICDs) may be recommended for patients at high risk of sudden cardiac death, and cardiac resynchronization therapy (CRT) can be beneficial in selected cases. Heart transplantation remains an option for end-stage disease refractory to medical therapy. Genetic counseling and cascade family screening with echocardiography are strongly recommended for at-risk relatives.

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