SCN5A and familial long QT syndrome: Recently, the genes associated with LQTS linked to chromosomes 3 (LQT3), 7 (LQT2), and 11 (LQTl) were identified as SCN5A, the cardiac sodium channel gene and as human ether-a-go-go-related gene (hERG) and KvLQTl potassium channel genes.