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GEN News Highlights : Mar 21, 2007

Prenatal Testing for X-Linked Mental Retardation a Possibility with New Discovery

Investigators from Cambridge Institute and Sanger Institute believe that their finding of mutated gene ZDHHC9 can be used as a molecular diagnostic.

Researchers identified a novel gene mutation that causes X-linked mental retardation, according to an article to be published online in The American Journal of Human Genetics.

"We have identified the cause of problems in certain families and are able to tell whether or not women are carriers of the condition," says F. Lucy Raymond, Ph.D.,  of the Cambridge Institute of Medical Research and one of the investigators. "Consequently, the families that had previously chosen to forego having children because there was no method of testing can now be tested. We have been able to test a substantial number of people to identify whether or not they are carriers, and we can offer prenatal testing to the carriers who want it."

Dr. Raymond and Patrick S. Tarpey of Wellcome Trust Sanger Institute, another researcher on the study, describe the ZDHHC9 gene found in those with severe retardation as being mutated to the point of entirely losing function.
Working through a large, international collaboration, the researchers collected genetic samples from 250 families in which at least two boys have mental retardation.

"ZDHHC9 is a novel gene," remarks Dr. Raymond. "This gene would not have been predicted to play a role in mental retardation based on the previous genetics work. It was found only because we were systematically looking at all the genes on the X chromosome irrespective of what they do."