KCNQ4

The KCNQ4 gene provides instructions for making a protein called potassium voltage-gated channel KQT-like protein 4. The KCNQ4 protein is part of a protein family that forms channels to transport positively charged potassium atoms (potassium ions) between neighboring cells. The channels, made from four protein subunits, play a key role in the ability of cells to generate and transmit electrical signals. The specific function of a potassium channel depends on its protein components and its tissue location. Potassium channels made with the KCNQ4 protein are found in the inner ear and along part of the nerve pathway from the ear to the brain (auditory pathway). KCNQ4 potassium channels are also found in small numbers in the heart and some muscles.

Because KCNQ4 potassium channels are present in the inner ear and auditory pathway, researchers have focused on their role in hearing. Hearing requires the conversion of sound waves to electrical nerve signals. This conversion involves many processes, including maintaining the proper level of potassium ions in the inner ear. Although the exact role of KCNQ4 channels remains unknown, these channels appear to be critical for the efficient transmission of electrical nerve signals. KCNQ4 channels may help recycle potassium ions within the inner ear to maintain the proper potassium ion balance.

nonsyndromic deafness - caused by mutations in the KCNQ4 gene

Several KCNQ4 mutations have been reported in individuals with a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNA2. Most KCNQ4 mutations change one of the building blocks (amino acids) used to make the KCNQ4 protein. Nearly all of these changes affect the region of the protein that forms the pore or channel opening. As a result, the channel does not function properly and normal potassium ion levels may be disturbed. Two mutations delete part of the KCNQ4 gene, which results in an abnormally small KCNQ4 protein that cannot form functional channels. It is unclear whether deafness results from disturbed potassium levels within the inner ear, alterations in the auditory pathway, or both.