SQT3 variant (linked to the inward rectifier potassium current I <sub>K1</sub>) of SQTS, results from a gain-of-function mutation (Kir2.1 D172N) in the KCNJ2-encoded channels, which is associated with ventricular fibrillation (VF).
The SQTS variant 3 is linked to D172N mutation to the KCNJ2 gene that causes a gain-of-function to the inward rectifier potassium channel current (I <sub>K1</sub>), which shortens the ventricular action potential duration (APD) and effective refractory period (ERP).
A gain-of-function <i>KCNJ2</i> D172N mutation in KCNJ2-encoded Kir2.1 channels underlies one form of short QT syndrome (SQT3), which is associated with increased susceptibility to arrhythmias and sudden death.
One form of the short QT syndrome (SQT3) has been linked to the D172N gain-in-function mutation to Kir2.1, which preferentially increases outward current through channels responsible for inward rectifier K(+) current (I(K1)).