Usher syndrome type 3

Usher syndrome type III is characterized by postlingual, progressive hearing loss, variable vestibular dysfunction, and onset of retinitis pigmentosa symptoms, including nyctalopia, constriction of the visual fields, and loss of central visual acuity, usually by the second decade of life (Karjalainen et al., 1985; Pakarinen et al., 1995). For a discussion of phenotypic heterogeneity of Usher syndrome, see USH1 (276900). Genetic Heterogeneity of Usher syndrome Type III Usher syndrome type IIIB (614504) is caused by mutation in the HARS gene (142810) on chromosome 5q31.3. [from OMIM]