Usher syndrome: hearing loss with vision loss.

Usher syndrome (USH) is a clinically heterogeneous condition characterized by sensorineural hearing loss, progressive retinal degeneration, and vestibular dysfunction. A minimum test battery is described as well as additional clinical evaluations that would provide comprehensive testing of hearing, vestibular function, and visual function in USH patients. USH is also genetically heterogeneous. At least nine genes have been identified with mutations that can cause USH. The proteins encoded by these genes are thought to interact with one another to form a network in the sensory cells of the inner ear and retina.