May 11, 2008

Usher Syndrome

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The information provided in this Resource Guide was developed by the National Eye Institute (NEI) to help patients and their families in searching for general information about Usher syndrome. An eye care professional who has examined the patient’s eyes and is familiar with his or her medical history is the best person to answer specific questions.

What Is Usher Syndrome?

Usher syndrome is an inherited condition that causes 1) a serious hearing loss that is usually present at birth or shortly thereafter and 2) progressive vision loss caused by retinitis pigmentosa (RP). RP is a group of inherited diseases that cause night-blindness and peripheral (side) vision loss through the progressive degeneration of the retina, the light-sensitive tissue at the back of the eye that is crucial for vision.

Researchers have described three types of Usher syndrome-type I, type II and type III.

  • Individuals with Usher syndrome type I are nearly or completely deaf and experience problems with balance from a young age. They usually begin to exhibit signs of RP in early adolescence.
  • Individuals with Usher syndrome type II experience moderate to severe hearing impairment, have normal balance, and experience symptoms of RP later in adolescence.
  • Individuals with Usher syndrome type III are born with normal hearing but develop RP and then progressive hearing loss.

How is Usher syndrome inherited?

Chart of the Autosomal Recessive The Usher syndrome types are inherited as an autosomal recessive trait. This means that an affected person receives one abnormal gene from each of his or her parents. A person who inherits a gene from only one parent will be a carrier, but will not develop the disease.

A person with Usher syndrome must pass on one disease gene to each of his or her children. However, unless the person has children with another carrier of Usher genes, the individual’s children are not at risk for developing the disease. Currently we cannot reasonably test everyone for carrier status, but this may change in the years ahead.

How is Usher syndrome diagnosed?

Since individuals with Usher syndrome have both hearing and visual symptoms, we perform testing of both systems. This testing includes:

  1. visual function tests: visual fields and electroretinogram (ERG)
  2. a retinal examination
  3. hearing tests
  4. balance tests for all patients age ten years and older

Although some of the genes that cause Usher syndrome have been identified, the diagnosis is still based on ocular and clinical testing.

Is genetic testing for Usher syndrome available?

At this time, genetic testing for Usher syndrome is done only as part of research projects. This is due to many factors. Usher syndrome is not caused by only one gene. So far, 10 Usher genes have been mapped: 7 for type I, 3 for type II, and 1 for type 3. There are still more genes to find. A few of these genes have been sequenced and described. These are MYO7A, harmonin, CDH23, PCDH15, all causing type I. The usherin gene causes type II disease.

Finding the genes is a very important advance in the fight against Usher syndrome. Further study is required to characterize these genes, and determine how the mutated genes cause Usher syndrome. Additional genes that cause Usher syndrome also need to be identified. Several researchers throughout the world are working on Usher syndrome. Findings from this research may one day allow treatments for Usher syndrome to be developed.

National Eye Institute Research

Researchers at of the National Eye Institute have been following individuals with Usher syndrome (Research Protocol # 93-EI-0161.) They are available for patient examination and consultation. The vision and hearing of each patient is evaluated. In addition, samples of blood from each patient are studied to better understand the genes involved in Usher syndrome. Patients interested in participating in this research study should contact:

Meira R. Meltzer, MA, MS
Genetic Counselor
National Eye Institute
(301) 402-4175
meira.meltzer@nih.gov

Other Resources

Individuals with Usher syndrome may find the following organizations useful for more information on the disease and rehabilitation:

American Association of the Deaf-Blind (AADB)
814 Thayer Avenue, Suite 302
Silver Spring, MD 20910-4500
(301) 495-4403
(301) 495-4402–TTY
http://www.aadb.org/
Encourages independent living for individuals who are deaf-blind. Provides technical assistance to persons who are deaf-blind, families, educators, and service providers.

DB-LINK: National Information Clearinghouse on Children Who are Deaf-Blind
345 N. Monmouth Avenue
Monmouth, OR 97361
1-800-438-9376
1-800-854-7013–TTY
http://www.tr.wou.edu/dblink/
Offers information that assists education, medical, and service personnel in providing comprehensive services infants, toddlers, children, and youth who are deaf-blind in the U.S.

(The) Foundation Fighting Blindness
Executive Plaza 1, Suite 800
11435 Cronhill Drive
Owings Mills, MD 21117-2220
1-888-394-3937
1-800-683-5555 (TDD)
(410) 568-0150
(410) 363-7139 (TDD)
http://www.blindness.org
Acts as a clearinghouse and distributor of self-help program information. Sponsors research on the cause, prevention, and treatment of retinitis pigmentosa, Usher’s syndrome, macular degeneration, and other retinal degenerative conditions. Conducts education programs for those affected by the disorders as well as professionals and the general public. Coordinates a national information and referral service and the Retinal Donor program. Publishes newsletters and other publications.

Helen Keller National Center for Deaf-Blind Youths & Adults (HKNC)
111 Middle Neck Road
Sands Point, NY 11050
(516) 944-8900
http://www.hknc.org/
Offers intensive and comprehensive rehabilitation training to individuals who are deaf-blind. Provides evaluation and training in communication skills, adaptive technology, orientation and mobility, independent living, work experience, and other support services.

National Family Association for Deaf-Blind (NFADB)
111 Middle Neck Road
Sands Point, NY 11050
1-800-255-0411
http://www.nfadb.org/
Serves as the largest national network of families focusing on issues surrounding deaf blindness.

National Organization for Rare Disorders
55 Kenosia Avenue
P.O. Box 1968
Danbury, CT 06813-1968
1-800-999-6673
(203) 744-0100
(203) 797-9590 (TDD)
http://www.rarediseases.org
Acts as a clearinghouse for information about rare disorders. Fosters networks between families with similar disorders. Educates the general public and medical profession about the existence, diagnosis, and treatment of rare disorders.

Office of Rare Diseases, National Institutes of Health
6100 Executive Boulevard
Room 3B01, MSC 7518
Bethesda, MD 20892
(301)402-4336
http://rarediseases.info.nih.gov
Coordinates the Rare Disease Clinical Research Database (RDCRD). Offers information on more than 6,000 rare diseases, current research and clinical trials, and support groups.

For additional information, you may also wish to contact a local library.

Medical Literature

Below is a sample of the citations available through MEDLINE/PubMed, a service of the National Library of Medicine. MEDLINE/PubMed provides access to over 11 million medical literature citations from 1966 to the present and includes links to many sites providing full text articles and other related resources. You can conduct your own free literature search by accessing MEDLINE through the Internet at http://medlineplus.nlm.nih.gov/hinfo.html. You can also get assistance with a literature search at a local library.

To obtain copies of any of the articles listed below, contact a local community, university, or medical library. If the library you visit does not have a copy of a particular article, you may usually obtain it through an inter-library loan.

Please keep in mind that articles in the medical literature are usually written in technical language. We encourage you to share any articles you order with a health care professional who can help you understand them.

The Usher syndromes. Keats BJ, Corey, DP. LSU Medical Center, New Orleans, LA. American Journal of Medical Genetics 89(3):158-166, 1999
This article reviews the information known by 1999 about the different types of Usher syndromes and the different genes found that cause them. It concentrates mainly on the MYO7A gene.

Genetic heterogeneity of Usher Syndrome: Analysis of 151 families with Usher Type I. Astuto, LM, et al. American Journal of Human Genetics 67:1569-1574, 2000
This article gives genetic information about 151 Usher I families studied. It provides a better idea of the percentage of Usher I caused by each of the 6 genes that have been mapped so far. MYO7A accounted for the largest percentage of families in their study.

Early diagnosis of Usher syndrome in children. Mets, MB, et al. Northwestern University Medical School, Chicago, IL. Trans Am Ophthalmol Soc 98:237-242, 2000
This article reports the results of a screening study on children with severe to profound, preverbal hearing-impaired children for Usher syndrome by examination and ERG testing. They found that 10% of such children were diagnosed with Usher syndrome and conclude that all children with severe to profound, preverbal hearing impairment should be screened for Usher syndrome.

The National Eye Institute, part of the National Institutes of Health, is the Federal government’s principal agency for conducting and supporting vision research. Inclusion of an item in this Information Resource Guide does not imply the endorsement by the National Eye Institute or the National Institutes of Health.

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