KCNH2

About KCNH2

KCNH2 on chromosome 7q36.1 encodes the alpha subunit of the hERG potassium channel, which carries the rapid delayed rectifier current that helps end each heartbeat by repolarizing cardiac muscle cells. Loss of function variants cause long QT syndrome type 2, one of the three most common forms of congenital long QT syndrome, which predisposes to the dangerous arrhythmia torsades de pointes, fainting, and sudden cardiac death. In type 2, events are classically triggered by sudden loud noises such as an alarm clock, or by emotional stress. Gain of function variants cause short QT syndrome. The hERG channel is also notorious in drug development because many unrelated medications can block it and prolong the QT interval, and several drugs have been withdrawn from the market for this reason, so screening compounds for hERG activity is a standard step in drug safety testing.