Twelve additional genes encoding either ion channel subunits (KCNJ5, KCNE1, KCNE2, and SCN4B) or proteins that regulate ion channel function (AKAP9, CAV3, ANKB, SNT1, CALM1, and CALM2) have been associated with LQTS; however, most of them are only rarely implicated (<1%) [7]. Here, CALM2 is linked to familial long QT syndrome.