KCNA3 and familial long QT syndrome: Although a major LQTS subtype with types 1 and 2, LQT3 comprises just about ≈5% to 10% of patients with LQTS, Wilde et al. provided one of the most current and detailed backgrounds in LQTS 3, and they explained in detail the significant difference of this phenotype from the other types 1 and 2, which is in the sodium channel mutation versus the potassium channel mutation [14].