Usher syndrome is a combination of retinitis pigmentosa and sensorineural hearing loss with or without vestibular dysfunction. Usher syndrome represents 50% of all cases with deafness and blindness. Usher syndrome is inherited in an autosomal recessive manner. Three major clinical types can be distinguished. Usher syndrome type I (USH1) is characterized by severe to profound congenital hearing loss, RP and vestibular areflexia. Patients with Usher syndrome type II (USH2) have moderate to severe hearing loss, RP and normal or variable vestibular function. Patients with Usher syndrome type III (USH3) have progressive hearing loss, RP and variable vestibular function.
Indications for genetic testing:
1. Confirmation of clinical diagnosis
2. Carrier testing for at-risk family members
3. Genetic counseling
4. Prenatal diagnosis for known familial mutation