Researchers funded by the National Institute of Child Health and Human Development (NICHD) have come one step closer to identifying one of the causes of previously unexplained mental retardation. The researchers report finding a single gene on the X chromosome, called AGTR2 for short, that when abnormal, appears to result in mental retardation (MR). The study, by Dr. Anand K. Srivastava and colleagues of the J.C. Self Research Institute of Human Genetics at the Greenwood Genetic Center in South Carolina, is published in the June 28 issue of Science.
"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 NICHD. "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."
Like an instruction manual, a gene contains information that tells the body how to make one or more specific proteins. A protein, in turn, performs a specific activity or group of activities within the body's cells. When a gene is mutated, or altered, however, it will produce an altered protein or will not produce a protein at all. Often, a gene mutation does not noticeably affect the body. Other gene mutations, however, can result in disease or disrupt normal development.
The researchers linked a mutation in the AGTR2 (Angiotensin II receptor 2) gene to mental retardation by studying a female patient with unexplained MR. The researchers knew that this patient had a chromosome translocation between one of the X chromosomes and one of the number 7 chromosomes, meaning that during development, two of her chromosomes broke, and then switched pieces. They suspected that this translocation resulted in a mutation in one of the genes on the broken X chromosome and that the mutation could have resulted in the patient's developmental disabilities. To t
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NIH/National Institute of Child Health and Human Development