The long-QT syndrome that shows segregation in iPSCORE family 2 (Figure 4A; Table S1A) is caused by the p.W1001∗ mutation in KCNH2, which encodes the α subunit of a potassium ion channel essential for the final repolarization of the ventricular action potential (Kupershmidt et al., 2002). This evidence concerns the gene KCNH2 and Prolonged QT interval.