CALM3 and familial long QT syndrome: In order to investigate the effect of the LQTS-associated variant CaM E140G on the voltage-dependent characteristics of Cav1.2 whole-cell currents (ICav1.2), patch-clamp electrophysiology was performed on HEK293-Cav1.2 cells transiently transfected to overexpress CaM-WT or E140G (Fig. 3A).