The KCNE2 gene encodes the subunit of a voltage gated potassium channel. By associating with the pore forming protein KCNH2, it generates a rapid delayed-rectifier channel. KCNE2 is responsible for modulating the gating kinetics and enhancing the stability of the channel complex. As it regulates several cardiac ion channels, it is integral to the maintenance of the heart rate and rhythm.
Mutations in KCNE2 have been associated with Long QT Syndrome 6 (LQT6). These mutations alter the protein’s functioning, resulting in slowly-opening and rapidly-closing channels that decrease the flow of potassium ions out of the cells. This causes delayed repolarization of the heart following a heartbeat and results in arrhythmia. In LQT6, also known as Romano-Ward syndrome, this can lead to syncope, seizures and even sudden death. A mutation in the gene has also been linked to rare cases of familial atrial fibrillation 4. The mutation alters the protein function leading to an increase in the flow of potassium ions through certain channels. The enhanced ion transport results in uncoordinated electrical activity in the atria of the heart.