KCNJ2 and Familial short QT syndrome: To date, current data concerning SQTS and overlapping phenotypes included a total of 34 rare variants (31 missense and four radical -one indel and three nonsense-) located in seven different genes (CACNA1C, CACNB2, KCNH2, KCNJ2, KCNQ1, SLC22A5 and SLC4A3).