USH1G

The USH1G gene provides instructions for making a protein called SANS. This protein is found in cells of the inner ear and the part of the eye that detects light and color (the retina). SANS interacts with other proteins, forming a larger protein complex that is critical for the development and function of the retina and inner ear.

In the inner ear, SANS promotes the proper development and maintenance of the hair bundles, tufts of hairlike projections on cells lining the inner ear. These hairlike projections, called stereocilia, bend in response to sound waves and transmit signals to the brain.

In the retina, SANS probably plays a role in the formation and maintenance of specialized retinal cells that detect light and color (photoreceptor cells).

Usher syndrome - caused by mutations in the USH1G gene

At least five mutations in the USH1G gene have been shown to cause Usher syndrome type 1G. Some of the mutations in the USH1G gene involve changes that lead to the production of an abnormally short, and probably nonfunctional, SANS protein. Other mutations lead to changes in single protein building blocks (amino acids) in the SANS protein, which alter its function. An abnormal SANS protein prevents the proper development of the inner ear and retina, leading to the hearing and vision loss characteristic of Usher syndrome.