Loss-of-function mutations of KV11.1 reduce the amplitude of IKr and lead to long QT syndrome 2 (LQTS2).115 About 300 different KV11.1 mutations are linked to LQTS2.116 These mutations cause loss of KV11.1 channel function by a range of mechanisms, including reducing channel synthesis, suppressing trafficking to the cell membrane, altering channel gating kinetics, or suppressing ion permeation through the channel pore.116 Most mutations appear to affect trafficking. Here, KCNH2 is linked to familial long QT syndrome.