KCND2 and familial long QT syndrome: It has been reported that KCND2 and KCND3 (Frank-Hansen et al., 2005), encoding of the voltage-gated potassium channel alpha subunits, Kv4.2 and Kv4.3, conducting the fast transient outward K+ current (Ito,f) in the prolongation of AP duration, which may be associated with the development of LQTS in the myocardium.