BACK TO USHER SYNDROME OVERVIEW

There are three general categories of Usher syndrome. Type 1 and type 2 are the most common forms of Usher syndrome in the United States. These 2 types account for about 95% of all cases of the syndrome. A total of nine genes that cause Usher syndrome have been identified.

Type 1

Children with type 1 Usher syndrome are born profoundly deaf and have severe balance difficulties. Many of these children do not benefit from hearing aids and may be candidates for cochlear implants.

Because of the balance problems associated with type 1 Usher syndrome, children with this disorder are slow to sit without support. They typically are not able to walk until 18-24 months old.

These children usually begin to develop vision problems in early childhood, almost always by age 10. The vision loss is caused by retinitis pigmentosa (RP), a degenerative condition of the retina. Vision problems most often begin with difficulty seeing at night, but tend to progress to total blindness.

The associated genes are MY07A, USH1C, CDH23, PCDH15, and SANS.

Type 2

Those with type 2 Usher syndrome are born with moderate to severe hearing loss and normal balance. Most of these individuals can benefit from hearing aids and can communicate orally. Vision problems in those with type 2 Usher syndrome tend to progress more slowly than those in type 1, with the onset of RP often not apparent until adolescence or shortly after. Type 2 does not result in total blindness. Hearing loss usually remains stable.

The associated genes are USH2A, VLGR1, and WHRN.

Type 3

Children with type 3 Usher syndrome have typical hearing at birth. Although most children with the disorder have normal to near-normal balance, some may develop balance problems later on. Hearing and sight worsen over time, but the rate at which they decline can vary from person to person, even within the same family. A person with type 3 Usher syndrome may develop hearing loss by the teens, and he or she will usually require hearing aids by mid- to late adulthood. Night blindness usually begins sometime during puberty. Blind spots appear by the late teens to early adulthood, and, by mid-adulthood, the person is usually legally blind.

The associated gene is USH3A.

Sources: Cleveland ClinicGenetic and Rare Diseases Information Center; National Institute on Deafness and Other Communication Disorders

There is no known cure for Usher syndrome, but there are ways to manage its effects on hearing, balance, and vision.

The most efficient treatment plans involve early identification and intervention through tailored educational programs to prepare the individual for employment and independent living. Educational programs for Usher consider the severity of the hearing and vision loss as well as the child’s age and abilities.

Treatment for hearing loss may include hearing aids, assistive listening devices, cochlear implants, American Sign Language, and speech therapy.

Treatment for balance difficulties may include physical and occupational therapy and orientation and mobility (O&M) training. O&M training teaches the individual to get from point A to point B. It also helps him or her strengthen muscles, particularly the core, to improve balance.

Treatment for vision loss may include Braille instruction, auditory training, and low-vision services. Provided by an optometrists, low vision services can include the following: training to use optical and electronic devices correctly; training to help use remaining vision more effectively; and improving lighting and enhancing contrast.

Additionally, a high dose of vitamin A may slow retinitis pigmentosa, but not cure it, per the results of a long-term clinical trial supported by the National Eye Institute and the Foundation for Fighting Blindness. Researchers recommend that most adult patients with the common forms of RP take a daily supplement of 15,000 IU (international units) of vitamin A under the supervision of their eye care professional. As patients with type 1 Usher syndrome did not take part in the study, high-dose vitamin A is not recommended for them.

Sources: American Foundation for the Blind; National Eye Institute; National Institute on Deafness and Other Communication Disorders