SCN5A and Ventricular arrhythmia: Unlike type 3 long QT syndrome, in which most of the SCN5A mutations cause a significantly enhanced persistent INa contributing to the life-threatening ventricular arrhythmias (Malan et al., 2011; Ma et al., 2013), the mutation p.S1812X in our study did not alter the persistent INa in BrS-CMs.