By following clues left by thalidomide - the drug that caused birth defects infamous - researchers have identified a gene on chromosome 7 which can be responsible for some cases of autism. Meanwhile, another study showed that long stretch of chromosome 15 can hold even more genes that predispose children to the disease.
Autism affects about 1 in 500 children, preventing them to connect with others or communicate and causing repetitive and stereotyped behavior and often mental retardation. Researchers have implicated at least three and possibly up to 15 genes in disorder, and they suspect that toxic chemicals may also play a role.
high levels of studies thalidomide revealed autism and facial deformities and ears among those exposed to the drug in the fourth week of gestation. Similar brain and facial defects occur in mice engineered to lack HOXA1 , a gene known to be involved in early development. That's why a team led by Patricia Rodier at the University of Rochester in New York decided to look for a mutation in HOXA1 in humans.
57 autistic patients tested by the team, nearly 40% had a mutation in one copy of the gene (one of them had mutations in both). Of 166 family members who were also tested, more than a third had the mutation and those who are more likely to have mild versions of autistic traits. Among 225 unrelated controls, only 25% had the altered gene, the team reports in the December issue of Teratology .
The study is "a very important scientific achievement," says Marie Bristol -Power, who chairs the Autism Coordinating Committee at the National Institutes of Health (NIH) in Bethesda, Maryland. neuropathological data showed that everything that happens in autism occurs in the first 7 months of gestation. This research contributes to narrow the window of time for the first 3 to 4 weeks, she said.
Another discovery appears in the December issue of American Journal of Medical Genetics. Researchers led by Anne Spence and Moyra Smith at the University of California, Irvine, say an autistic 7 year old girl missing a stretch of about 1 million base pairs on one copy of chromosome 15 . previous linkage studies also pointed out that the area of the chromosome, so the genes that are normally found in the missing area are obvious candidates that may play a role in autism, the team concludes.
network autism NIH consists of 10 research programs at different institutions can now detect more people to HOXA1 and refine the search section on chromosome 15, said Bristol -Power. Finally, the work may lead to new tests that could predict whether a fetus is at risk for autism, or even drugs to treat the disease, she added.
Autism Research at the University of Rochester
NIH information on autism page
website of autism at the National Institute of child health and human development
homepage Moyra Smith
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