In 8/12 probands (66.7%), we found likely causative variants in known cardiomyopathy genes (TTN, DSP, SCN5A, TNNC1, TPM1, CRYAB, and MYH7), which were confirmed as de novo (six DCM, one HCM, and one RCM case, Table 1, Figure S1). The gene discussed is SCN5A; the disease is familial dilated cardiomyopathy.