KCNJ2
potassium inwardly rectifying channel subfamily J member 2
Normal Function
Health Conditions Related to Genetic Changes
Andersen-Tawil syndrome
More than 60 mutations in the KCNJ2 gene have been found to cause Andersen-Tawil syndrome, a disorder characterized by episodes of muscle weakness (periodic paralysis), changes in heart rhythm (arrhythmia), and physical abnormalities affecting the face, other parts of the head, and the limbs. Most of the mutations change a single protein building block (amino acid) in the KCNJ2 protein.
Mutations in the KCNJ2 gene lead to the production of a nonfunctional potassium channel. Some mutations change the shape of the channel so it cannot transport potassium ions, while other mutations prevent the channels from being inserted correctly into the cell membrane. Many KCNJ2 mutations prevent PIP2 from effectively binding to and activating potassium channels. If the KCNJ2 protein is unable to bind to PIP2, the channels remain closed and potassium ions are unable to flow across the cell membrane. Researchers believe that problems with PIP2 binding are a major cause of Andersen-Tawil syndrome.
A loss of this channel's function in skeletal and cardiac muscle cells disrupts the normal flow of potassium ions out of these cells, resulting in periodic paralysis and an irregular heart rhythm. It is not known how mutations in the KCNJ2 gene contribute to the physical abnormalities often found in Andersen-Tawil syndrome.
More About This Health ConditionRelated Conditions
Andersen-Tawil syndromeShort QT syndromeFamilial atrial fibrillation
Health Conditions Related to Genetic Changes
More than 60 mutations in the KCNJ2 gene have been found to cause Andersen-Tawil syndrome, a disorder characterized by episodes of muscle weakness (periodic paralysis), changes in heart rhythm (arrhythmia), and physical abnormalities affecting the face, other parts of the head, and the limbs. Most of the mutations change a single protein building block (amino acid) in the KCNJ2 protein.
Mutations in the KCNJ2 gene lead to the production of a nonfunctional potassium channel. Some mutations change the shape of the channel so it cannot transport potassium ions, while other mutations prevent the channels from being inserted correctly into the cell membrane. Many KCNJ2 mutations prevent PIP2 from effectively binding to and activating potassium channels. If the KCNJ2 protein is unable to bind to PIP2, the channels remain closed and potassium ions are unable to flow across the cell membrane. Researchers believe that problems with PIP2 binding are a major cause of Andersen-Tawil syndrome.
A loss of this channel's function in skeletal and cardiac muscle cells disrupts the normal flow of potassium ions out of these cells, resulting in periodic paralysis and an irregular heart rhythm. It is not known how mutations in the KCNJ2 gene contribute to the physical abnormalities often found in Andersen-Tawil syndrome.
Mutations in the KCNJ2 gene can also cause a heart condition called short QT syndrome, which is a type of arrhythmia. In people with this condition, the cardiac muscle takes less time than usual to recharge between beats. This change increases the risk of abnormal heart rhythm that can cause fainting or sudden death.
At least two mutations in the KCNJ2 gene have been found to cause short QT syndrome in a small number of affected families. These mutations change single amino acids in the KCNJ2 protein, which increases the activity of channels made with this protein. As a result, more potassium ions flow out of cardiac muscle cells at a critical time during the heartbeat, which can lead to an irregular heart rhythm.
MedlinePlus Genetics provides information about Familial atrial fibrillation