KCNA3 and long QT syndrome 5: LQT1, LQT5, JLN1, JLN2: KCNQ1 (causing LQT1 and JLN1) and KCNE1 (causing LQT5 and JLN2) encode respectively for the alpha (KvLQT1) and the beta (MinK) subunits of the potassium channel conducting the IKs current, the slow component of the delayed rectifier current (IK) the major repolarizing current during phase 3 of the cardiac action potential.