TTN and familial dilated cardiomyopathy: DCM has genetic (truncating TTN, LMNA, pathogenic desmosome, and BAG3 gene variants) and nongenetic (ethanol, cocaine, anthracyclines, viral and bacterial myocarditis, and peripartum cardiomyopathy) causes leading to LV systolic dysfunction, which is not explained by HTN, valvular heart disease, or CAD.