Usher syndrome is a rare, inherited disorder that involves loss of hearing and sight. Hearing loss is due to the inability of the auditory nerves to send sensory input to the brain. This is called sensorineural hearing loss.

The vision loss, called retinitis pigmentosa (RP), usually happens after age ten. RP is a deterioration of the retina. The retina is a layer of light-sensitive tissue that lines the back of the eye. It changes visual images into nerve impulses in the brain that allow us to see. RP slowly gets worse over time.

Nerve and Retina of the Eye
Normal Anatomy of the Eye
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Three types of Usher syndrome have been identified: types I, II, and III. The age of onset and severity of symptoms separate the different types.

Usher syndrome is caused by a genetic mutation. A child must inherit one defective gene from each parent in order to develop Usher syndrome. A child with one defective gene is a carrier and will not have any symptoms. It is not clear what causes the mutation in the gene.