JOHN A. GERMILLER MD, PhD | Pediatric Otolaryngology | 2007 |
Usher syndrome is an autosomal recessive disorder characterized by retinitis pigmentosa, SNHL, and variable vestibular system pathology. Various types exist. Usher syndrome type I is the most severe type, with profound deafness at birth and severe vestibular dysfunction. It is caused by mutations in the MYO7A gene, which encodes a protein involved in proper functioning of the stereociliary bundle on sensory hair cells. Patients with type II Usher syndrome have less severe hearing impairment than in type I disease. Type III Usher's syndrome is characterized by intact hearing at birth that progressively deteriorates throughout life, without balance disturbance. In all forms of Usher syndrome, early referral to an ophthalmologist is important to monitor for retinitis pigmentosa and its associated vision loss. Hearing loss must be monitored especially carefully and managed aggressively in this syndrome because of the additional disability possible from multiple sensory impairments.