The researchers found a single gene, Angiotensin II receptor 2 known as AGTR2 on the X chromosome that may trigger mental retardation when the gene is abnormal. Srivastava, associate research geneticist in Greenwood and adjunct research professor at Clemson, has linked this gene to mental retardation in males.

"The identification of a single gene mutation that may prove to be the cause of some cases of mental retardation is very encouraging," said Duane Alexander, M.D., director of the National Institute of Child Health and Human Development, which funded the study. "This advance not only may lead to insights into a variety of new therapies, but may also help us to better understand the processes involved in normal brain development."

The research was conducted at the Center for Molecular Studies at the J.C. Self Research Institute of Human Genetics in Greenwood. "Identification of genes that cause mental retardation and other human disabilities is a major focus of the institute," said Dr. Charles Schwartz, head of the research program.

A single patient led scientists to research the connection. Knowing beforehand that the mentally retarded female patient had an abnormally arranged X chromosome, they theorized that a single gene was silenced by the rearrangement, resulting in the patient's developmental disabilities. Dr. Srivastava's team identified the gene that was silenced and then studied it in 590 male patients with unexplained mental retardation, identifying mutations in eight of them.

"Although an AGTR2 mutation appeared to be present in only 1.5 percent of males with unexplained mental retardation, this percentage is significant," said James Hanson, M.D
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Contact: Peter Kent
peter.kent@clemsonews.clemson.edu
864-656-0937
Clemson University
27-Jun-2002