Clinically, more than 300 loss-of-function mutations in KCNQ1 have been found to induce functional defects to the IKs current, causing long QT syndrome (LQTS) that predisposes patients to life-threatening cardiac arrhythmia (Schwartz et al., 2012; Wang et al., 1996). This evidence concerns the gene KCNQ1 and familial long QT syndrome.