A genetically heterogeneous cardiac disorder caused by pathogenic variants in the TNNT2 gene and inherited in an autosomal dominant manner. Affected individuals present with a spectrum of cardiomyopathy phenotypes, including dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), and left ventricular noncompaction (LVNC). Clinical features may include heart failure, ventricular arrhythmias, and sudden cardiac death. Overlapping or mixed cardiomyopathy phenotypes, as well as variable expressivity within families, have also been reported.