Originally characterized as an AD inheritance syndrome, called Romano–Ward syndrome (LQT1–6 and LQT9–13), today 17 LQTS-associated genes are known (AKAP9, ANK2, CACNA1C, CALM1, CALM2, CAV3, KCNE1, KCNE2, KCNH2, KCNJ2, KCNJ5, KCNQ1, SCN1B, SCN4B, SCN5A, SNTA1 and TRDN) (Table 1) [29,30]. This evidence concerns the gene TRDN and familial long QT syndrome.