Usher Syndrome II

Usher syndrome type II occurs at least as frequently as type I, but because type II may be under diagnosed or more difficult to detect, it could be up to three times as common as type I.

Mutations in the MASS1 (also called VLGR1) and USH2A genes cause Usher syndrome type II. Usher syndrome type II may be caused by mutations in any of three different genes, two of which have been identified to date. These genes are called USH2A and MASS1. Usherin, the protein made by the USH2A gene, is located in supportive tissue in the inner ear and retina. Usherin is critical for the proper development and maintenance of these structures, which may help explain its role in hearing and vision loss. The precise function of the protein made by the MASS1 gene is not yet known.

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