KCNQ1 and long QT syndrome 1: The first heart channelopathy to be discovered was a congenital form of long QT syndrome (LQT1) due to mutations in KCNQ1 encoding the main subunit (Kv7.1) of the K channel responsible for the slow delayed rectifier current (IKs) in cardiomyocytes (Wang et al., 1996).