DFNB31

The DFNB31 gene provides instructions for making a protein called whirlin. Whirlin belongs to a group of proteins that have specialized regions called PDZ domains. PDZ domains are sites of protein-protein interactions that are important for normal cell functions.

Whirlin is made in several types of cells, but it has been best studied in cells from the inner ear and the light-sensitive tissue at the back of the eye (the retina). In the inner ear, it appears that whirlin is needed for normal hearing. Hearing requires the conversion of sound waves to nerve impulses that are transmitted via the auditory nerve to the brain. Researchers suggest that whirlin plays an important role in the development and maintenance of stereocilia, the hairlike structures that project from specialized cells called hair cells. Stereocilia line the inner ear and bend in response to sound waves. This bending motion is critical for converting sound waves to nerve impulses. In the retina, whirlin's function is not well understood. Research findings indicate that it may be important in the development and function of photoreceptor cells, which detect light and color.

nonsyndromic deafness - caused by mutations in the DFNB31 gene

Researchers have identified two mutations in the DFNB31 gene that cause a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNB31. These mutations introduce a premature stop signal in the instructions for making whirlin. As a result, no protein is produced, or an abnormally small protein that is missing a PDZ domain is made. The abnormal whirlin protein or the absence of whirlin probably impairs the function of stereocilia, leading to hearing loss.