In addition to the potassium channel genes KCNH2 (SQT1), KCNQ1 (SQT2) and KCNJ2 (SQT3), the cardiac chloride-bicarbonate exchanger AE3 encoded by SLC4A3 is a main cause for SQTS. The gene discussed is SLC4A3; the disease is Familial short QT syndrome.