KCNH2 and familial long QT syndrome: Although12.9% of the cells displayed arrhythmic activity such as EADs, the iPSC modeldemonstrated that even mild arrhythmias can be captured in LQTS studies.Treatment with a human ether-a-go-go-related gene (hERG) channel activator normalized APD, confirming the accuracyof the iPSC-CMs in reflecting patient responses.