SCN5A and familial dilated cardiomyopathy: In contrast, only iPSC-CMs with multiple gene mutations (SCN5a p.C335R and TTNtv) showed a more significant dysregulation of sarcomere structures compared to iPSC-CMs with SCN5a p.C335R or healthy controls (Figure 4), which may explain the severity of the disease and earlier onset of DCM in patient IV.1.