This potassium channel is controlled by G proteins. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. Can be blocked by external barium (By similarity). Predominantly detected in fetal and adult heart. Defects in KCNJ8 may be associated with susceptibility to J-wave syndromes, a group of heart disorders characterized by early repolarization events as indicated by abnormal J-wave manifestation on electrocardiogram (ECG). The J point denotes the junction of the QRS complex and the ST segment on the ECG, marking the end of depolarization and the beginning of repolarization. An abnormal J wave is a deflection with a dome or hump morphology immediately following the QRS complex of the surface ECG. Examples of J-wave disorders are arrhythmias associated with an early repolarization pattern in the inferior or mid to lateral precordial leads, Brugada syndrome, some cases of idiopathic ventricular fibrillation (VF) with an early repolarization pattern in the inferior, inferolateral or global leads, as well as arrhythmias associated with hypothermia. Disease susceptibility is associated with variants affecting the gene represented in this entry. The disease may be caused by variants affecting distinct genetic loci, including the gene represented in this entry. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ8 subfamily.