What is Usher syndrome?

Usher syndrome is the most common genetic cause of combined deafness and blindness. 

More than 400,000 people are estimated to have Usher syndrome worldwide.

Usher syndrome impacts three major senses in the body:

Hearing: Children with Usher syndrome are born with or develop hearing loss. It’s estimated that upward of 10 percent of individuals with congenital bilateral, sensorineural hearing loss have Usher syndrome.

Vision: Progressive vision loss in Usher syndrome is caused by retinitis pigmentosa (RP). RP causes the light-sensing cells in the retina to gradually deteriorate. The first sign of RP is nyctalopia - difficulty seeing in dim lighting. Nyctalopia is also known as night blindness. This symptom is often overlooked or undetected for years as the child naturally and cleverly adapts to the slow change of function. Also, since vision is only affected in dim lighting (restaurants, at bedtime, etc.), the loss of visual function in the dark can be incorrectly attributed to inattentiveness, distraction, or clumsiness.

The second symptom of RP is a slow and progressive narrowing of the visual fields, leading to tunnel vision. With RP, visual acuity/central vision often remains good until the final stages of vision loss. Cataracts are common in individuals with RP/Usher syndrome. Some individuals will develop CME - cystoid macular edema. You can discuss both of these conditions with your ophthalmologist.  

RP is inherited and can occur in individuals who have typical hearing. RP plus hearing loss CAN mean Usher syndrome, but hearing loss can have many causes. The only way to make sure someone has Usher syndrome is through genetic testing. 

Balance: Balance is achieved and maintained through input from your eyes, the vestibular organs in the inner ear, and the sensory systems of the body, such as the skin, muscles, and joints. Individuals with type 1, and some with type 3 Usher syndrome experience severe balance issues due to vestibular dysfunction.

Types: There are three clinical types of Usher syndrome: type 1, type 2 and type 3, which are distinguished by the age of onset and the severity of symptoms. There are at least 10 subtypes of Usher syndrome, as determined by the genes that are involved. Variants on 5 genes cause the symptoms known as Usher type 1; variants on three genes cause the sUsher type 2, and variants on 2 genes cause Usher type 3. One cannot determine the genetic type by clinical testing; DNA testing is the only reliable way of determining the true genetic type.

You are not alone.