As a proof-of-concept for 3D tissue modeling with isogenic iPSCs, we targeted KCNH2, encoding the potassium channel Kv11.1 or hERG, where the N588D and N588K mutations uniquely cause two distinct clinical disorders, long (LQTS) and short (SQTS) QT syndromes respectively22–26. The gene discussed is KCNA3; the disease is Familial short QT syndrome.