KCNQ3 gene

The KCNQ3 gene provides instructions for making potassium channels that regulate electrical signals in the brain, preventing neurons from becoming overactive.

Normal Function

The KCNQ3 gene belongs to a family of genes that provide instructions for making potassium channels. These channels transport positively charged potassium ions into and out of cells, which is essential for generating and transmitting electrical signals. In the brain, KCNQ3 channels are active in nerve cells (neurons), where they transmit a specific electrical signal called the M-current. This current prevents neurons from being constantly active or excitable.

Potassium channels are composed of four alpha subunits. While four KCNQ3 subunits can form a channel, they can also interact with subunits from the KCNQ2 gene to form functional channels that transmit a much stronger M-current.

Health Conditions Related to Genetic Changes

Benign familial neonatal seizures

Mutations in the KCNQ3 gene have been identified in some individuals with benign familial neonatal seizures (BFNS), a condition characterized by recurrent seizures in newborns. These seizures typically begin around the third day of life and resolve within one to four months.

The identified mutations change single amino acids in the KCNQ3 protein, resulting in a reduced M-current. Researchers believe that a 25 percent reduction in this current is sufficient to cause the excessive neuronal excitability that leads to seizures. It is thought that KCNQ2 and KCNQ3 proteins play a major role in preventing excitability in newborns, but that other mechanisms develop during infancy, which explains why the seizures typically stop by four months of age.

Genomic Location

The KCNQ3 gene is found on chromosome 8.