Definitive disease-causing variants in both disorders have been identified in cardiac actin (ACTC1), β-myosin heavy chain (MYH7), the troponins (TNNT2, TNNI3), and α-tropomyosin (TPM1), with putative DCM mutations also identified in cardiac troponin-c (TNNC1) and myosin binding protein C (MYBPC3) [1]. The gene discussed is ACTC1; the disease is familial dilated cardiomyopathy.