potassium inwardly rectifying channel subfamily J member 8
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From NCBI Gene:
Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins. Defects in this gene may be a cause of J-wave syndromes and sudden infant death syndrome (SIDS). [provided by RefSeq, May 2012]
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).
Covered on Genetics Home Reference:
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.
Hypertrichotic osteochondrodysplasia (HTOCD): A rare disorder characterized by congenital hypertrichosis, neonatal macrosomia, a distinct osteochondrodysplasia, and cardiomegaly. The hypertrichosis leads to thick scalp hair, which extends onto the forehead, and a general increase in body hair. In addition, macrocephaly and coarse facial features, including a broad nasal bridge, epicanthal folds, a wide mouth, and full lips, can be suggestive of a storage disorder. About half of affected individuals are macrosomic and edematous at birth, whereas in childhood they usually have a muscular appearance with little subcutaneous fat. Thickened calvarium, narrow thorax, wide ribs, flattened or ovoid vertebral bodies, coxa valga, osteopenia, enlarged medullary canals, and metaphyseal widening of long bones have been reported. Cardiac manifestations such as patent ductus arteriosus, ventricular hypertrophy, pulmonary hypertension, and pericardial effusions are present in approximately 80% of cases. Motor development is usually delayed due to hypotonia. Most patients have a mild speech delay, and a small percentage have learning difficulties or intellectual disability. [MIM:239850]
Sudden infant death syndrome (SIDS): SIDS is the sudden death of an infant younger than 1 year that remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of clinical history. Pathophysiologic mechanisms for SIDS may include respiratory dysfunction, cardiac dysrhythmias, cardiorespiratory instability, and inborn errors of metabolism, but definitive pathogenic mechanisms precipitating an infant sudden death remain elusive. [MIM:272120]