Clinical Information

The cardiomyopathies are a group of disorders characterized by disease of the heart muscle. Cardiomyopathy can be caused by either genetic (inherited) factors or nongenetic (acquired) causes such as infection or trauma. When the presence or severity of the cardiomyopathy observed in a patient cannot be explained by acquired causes, genetic testing for the inherited forms of cardiomyopathy may be considered. The hereditary forms of cardiomyopathy include hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy (ARVC or AC), left ventricular noncompaction, and restrictive cardiomyopathy.(1) Cardiomyopathy may also be a feature of an underlying systemic condition such as Noonan syndrome, a mitochondrial disorder, a muscular dystrophy, or a metabolic storage disorder.(1) In these cases, cardiomyopathy may be the first feature to come to attention clinically.

Cardiac arrhythmias are a group of conditions characterized by abnormal heart rhythms. Arrhythmias can be caused by either genetic (inherited) factors or by nongenetic (acquired) causes such as medications and infection. The more common hereditary forms of cardiac arrhythmias include long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and Brugada syndrome.(2) Other inherited forms of arrhythmia can include, but are not limited to, ARVC and atrial fibrillation.(2) Additionally, other forms of inherited cardiomyopathies may first come to medical attention due to an associated arrhythmia. Cardiac arrhythmias can also be a feature of rarer, syndromic conditions including Andersen-Tawil syndrome, Cantu syndrome, Carvajal syndrome, Jervell and Lange-Nielsen syndrome, Naxos disease, Timothy syndrome, and Emery-Dreifuss muscular dystrophy.(2)

Inherited cardiomyopathies and inherited cardiac arrhythmias can follow autosomal dominant, autosomal recessive, X-linked, and digenic patterns of inheritance. Genes associated with mitochondrial inheritance of cardiomyopathy and cardiac arrhythmia are not assessed on this panel.