So far, 11 genetic loci (a segment of chromosome on which a certain gene is located) have been found to cause Usher syndrome, and nine genes have been pinpointed that cause the disorder. They are:
- Type 1 Usher syndrome: MY07A, USH1C, CDH23, PCDH15, SANS
- Type 2 Usher syndrome: USH2A, VLGR1, WHRN
- Type 3 Usher syndrome: USH3A
With so many possible genes involved in Usher syndrome, genetic tests for the disorder are not conducted on a widespread basis. Diagnosis of Usher syndrome is usually performed through hearing, balance, and vision tests. Genetic testing for a few of the identified genes is clinically available. To learn about laboratories that conduct clinical testing, visit the Web site www.GeneTests.org and search the laboratory directory by typing in the term “Usher syndrome.” Genetic testing for additional Usher syndrome genes may be available through clinical research studies.