LQT1 is associated with loss-of-function mutations in the KCNQ1 gene, which encodes for the α-subunit of the channel conducting the slowly activating delayed rectifier potassium current (IKs), while LQT2 arises from loss-of-function mutations in KCNH2 (also known as hERG), encoding the rapidly activating delayed rectifier potassium current (IKr). Here, KCNQ1 is linked to long QT syndrome 1.