The KCNH2 gene is located on chromosome 7q36.1, where it gives instructions for making the pore-forming (alpha) subunit of voltage-gated potassium channel (KV). This protein, made up of 1159 amino acids and weighing about 127 kDa, belongs to the 6-TM family of potassium channel. The KCNH2 subunits oligomerize to form a tetramer that inserts into the cell membrane to form the functional K+ channel, which is active in cardiac muscles. These subunits are involved in recharging the cardiac muscle after each heartbeat to maintain a regular rhythm.

Defects in the KCNH2 protein are the cause of long QT syndrome 2, and Short QT syndrome 1. Long QT syndrome is a disorder of the heart's electrical activity, characterized by a prolongation of the QT interval at basal ECG and by a high risk of life-threatening arrhythmias.