In order of frequency, LQT1 is followed by LQT2, which originates from loss-of-function mutations in the gene KCNH2, which produces a protein called human Ether-á-go-go-related gene (hERG, a subunit of Kv11.1, a voltage-gated potassium channel) that participates in the rapid delayed rectifier current of the cardiac action potential. The gene discussed is KCNH2; the disease is long QT syndrome 1.