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Nam Y. Huh/AP
Nine-year-old Charlie Blakey, who was diagnosed with autism at age 3, eats dinner at his
home in Oak Park, Ill.

Human Genome Offers Clues About the Origins of Autism

May 01, 2009 07:20 AM
by Emily Coakley
New studies of the human genome are revealing more about the genetic factors that could influence autism, as research into the mysterious condition continues.

The Quest to Understand Autism

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A trio of studies on the genetic roots of the condition published this week describe a common gene variation that, if fixed, could reduce autism's prevalence by as much as 15 percent

The BBC summarized the studies as examining “the human genome for small differences between people who have an [Autism Spectrum Disorder], and those who do not.”

The University of Pennsylvania led the biggest study, which involved 10,000 people. Results from that study suggest that genetic differences are associated with chromosome five. That chromosome and the variants were involved in the “production of proteins which help cells stick to each other, and make nervous connections,” according to the BBC.

The studies listed other variations that affected how brain cells moved to their proper places, connected with adjacent neurons, and maintained those connections.

One gene, CDH10, had a variant discovered in more than 65 percent of the cases of autism researchers studied.

“Until now, no common genetic variant has been identified with such overwhelming evidence to support its role in autism spectrum disorders,” said Dr. Margaret Pericak-Vance, a professor at the University of Miami, Reuters reported.
In 2007, the Autism Genome Project announced it had found several genes and abnormalities that are implicated in autism. The project studied the genomes of more than 1,100 families throughout the world who have two or more children with autism. Though the research didn’t yield clues to a cure, it did suggest that concerns about environmental factors in autism may be unfounded.

“The evidence suggests autism is over 90 percent caused by genes,” said Joseph Buxbaum, one of the study’s lead investigators, in a 2007 interview with ABC News.

“The puzzle is slowly being pieced together, and the science of autism is accelerating in promising ways,” said Simon Baron-Cohen, a University of Cambridge professor and autism expert, according to the BBC.

Baron-Cohen told the news service that researchers have now found 133 genes linked to autism.

Background: Autism’s rise

According to the U.S. Centers for Disease Control and Prevention, autism may affect one in every 150 people. Autism diagnosis rates have been climbing for years, and no one is sure why.

In Minneapolis, education officials are trying to figure out why there are so many children who speak Somali in autism programs. Minneapolis has the largest population of Somalis outside of East Africa. About six percent of the district's students speak Somali at home, but the same group accounts for nearly 25 percent of the children in autism programs.

And in California, the number of autism cases has risen sharply to more than 3,000 in 2006, up from just 205 in 1990, according to a study published in January. In that study, author Irva Hertz-Picciotto of the University of California-Davis, said more money should be spent researching environmental factors’ role in autism.

Reference: Autism resources online

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