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The official name of this gene is “Usher syndrome 2A (autosomal recessive, mild).”
USH2A is the gene's official symbol. The USH2A gene is also known by other names, listed below.
The USH2A gene provides instructions for making a protein called usherin. Usherin is an important component of basement membranes, which are thin, sheet-like structures that separate and support cells in many tissues. Usherin is found in the inner ear and the layer of light-sensitive tissue at the back of the eye (the retina). Although the function of usherin has not been well established, studies suggest that it is part of a group of proteins (a protein complex) that plays an important role in inner ear and retinal development. In these locations, the protein complex may also be involved in the function of synapses, which are junctions between nerve cells where cell-to-cell communication occurs.
The USH2A gene belongs to a family of genes called fibronectin type III domain containing (fibronectin type III domain containing).
A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.
Several mutations in the USH2A gene have been reported to cause retinitis pigmentosa. USH2A gene mutations are the most common cause of the autosomal recessive form of retinitis pigmentosa, accounting for 10 to 15 percent of all cases. This form of the disorder is described as nonsyndromic, which means that it is not part of a larger genetic syndrome (such as Usher syndrome, described below).
The USH2A gene mutations that cause autosomal recessive retinitis pigmentosa change single protein building blocks (amino acids) in the usherin protein. Through a mechanism that is not well understood, these genetic changes lead to the gradual breakdown of specialized light receptor cells (photoreceptors) in the retina. A loss of these cells underlies the progressive vision loss characteristic of this condition.
More than 200 mutations in the USH2A gene have been identified in people with Usher syndrome type IIA. Several of these mutations change single protein building blocks (amino acids) in the usherin protein. These mutations often lead to the production of an abnormally short version of the protein or prevent the cell from making any functional usherin. Other mutations insert or delete small amounts of DNA in the USH2A gene, which probably impairs the normal function of usherin. Researchers have not determined how a missing or altered usherin protein leads to the hearing impairment and vision loss that are characteristic of Usher syndrome type IIA.
It is unclear why some USH2A gene mutations result in Usher syndrome type IIA, while other mutations cause retinitis pigmentosa without hearing loss.
Cytogenetic Location: 1q41
Molecular Location on chromosome 1: base pairs 215,622,894 to 216,423,396
The USH2A gene is located on the long (q) arm of chromosome 1 at position 41.
More precisely, the USH2A gene is located from base pair 215,622,894 to base pair 216,423,396 on chromosome 1.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about USH2A helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
acids ; autosomal ; autosomal recessive ; basement membranes ; breakdown ; cell ; DNA ; gene ; protein ; receptor ; recessive ; retina ; syndrome ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.