RBM20 and familial dilated cardiomyopathy: Clinically, the features of DCM with an RBM20 mutation were reported as (1) the severely compromised cardiac systolic function leading to the need for heart transplantation at a very young age compared to that in DCM caused by mutations in other genes22, (2) higher incidence of sustained ventricular arrhythmias and sudden cardiac death than that in patients with a mutation in TTN23, and (3) higher incidence of atrial fibrillation (AF) than in patients with other idiopathic DCM16.