Romano-Ward syndrome, the autosomal dominant LQTS is sub classified in to LQT 1, which is the commonest form of LQTS and where the mutation is in the gene KVLQT1 on chromosome 11, LQT 2 in HERG on chromosome 7, LQT 3 in SCN5A on chromosome 3, LQT 4 in chromosome 4 and LQT 5 with mutation in Min K on chromosome 21. Here, KCNQ1 is linked to familial long QT syndrome.