What are the genetic changes related to Usher syndrome ?
Mutations in the ADGRV1, CDH23, CLRN1, MYO7A, PCDH15, USH1C, USH1G, and USH2A genes can cause Usher syndrome.  The genes related to Usher syndrome provide instructions for making proteins that play important roles in normal hearing, balance, and vision. They function in the development and maintenance of hair cells, which are sensory cells in the inner ear that help transmit sound and motion signals to the brain. In the retina, these genes are also involved in determining the structure and function of light-sensing cells called rods and cones. In some cases, the exact role of these genes in hearing and vision is unknown. Most of the mutations responsible for Usher syndrome lead to a loss of hair cells in the inner ear and a gradual loss of rods and cones in the retina. Degeneration of these sensory cells causes hearing loss, balance problems, and vision loss characteristic of this condition.  Usher syndrome type I can result from mutations in the CDH23, MYO7A, PCDH15, USH1C, or USH1G gene. At least two other unidentified genes also cause this form of Usher syndrome.  Usher syndrome type II is caused by mutations in at least four genes. Only two of these genes, ADGRV1 and USH2A, have been identified.  Mutations in at least two genes are responsible for Usher syndrome type III; however, CLRN1 is the only gene that has been identified.