The KCNQ1-p.R583H variant was previously reported to be associated with LQTS [15,16,17]; KCNH2-p.C108Y is a novel variant; and KCNH2-p.K897T and KCNE1-p.G38S were reported to influence the electrical activity of cardiac cells and to act as modifiers of the KCNH2 and KCNQ1 channels [9,18,19,20,21,22,23,24,25,26,27,28]. Here, KCNQ1 is linked to familial long QT syndrome.