Whole-cell patch-clamp recording of genome edited LQTS iPSC-CMs. (A) Actionpotential recordings from un-edited, piG269S, and ziG269S iPSC-CMs showing ventricular-like and atrial-like morphologies. All the LQTS iPSC-CMs displayed the marked APD prolongation in both ventricular-like and atrial-like iPSC-CMs. (B) APD50, APD70, and APD90 values in unedited control and LQTS iPSC-CMs. **P<0.01 when compared to control cells. Error bars show mean ± s.e.m. (C) Development of triggered activity in LQTS iPSC-CMs, manifested as EADs or even single and multiple triggered beats. The EADs or aberrant beats were indicated by red arrows.