Kir2.1 has a fundamental role in controlling the resting potential of cardiac myocytes and shaping the cardiac action potential. It is therefore likely that drugs affecting this channel will have an effect on cardiac excitability. Mutations in the KCNJ2 gene that encodes Kir2.1, reduce expression of the channel and cause a form of long QT syndrome (Andersen Syndrome, LQT7) that predisposes individuals to ventricular arrhythmias.Recognition that the dysfunction of this channel can lead to long QT has lead to it’s inclusion into the cardiac panel.