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Gene Variants Hold New Clues to Autism

Researchers Identify Gene Mutations That May Raise Risk of Autism Spectrum Disorders

DNA Duplications and Autism Risks

In the second study, Hakonarson and colleagues used the same genome-wide association approach to find genes that were either duplicated or deleted in those with autism or ASD. For this study, the researchers looked at 2,195 children with ASD and 2,519 children without ASD.

They found some previously reported genes, but also some new ones.

And the newly discovered gene variants tended to affect genes involved in cell adhesion, linking the findings to those in the first study.

Search for Genetic Variants

In another study, published online in the Annals of Human Genetics, Margaret Pericak-Vance, PhD, director of the Miami Institute for Human Genomics at the University of Miami Miller School of Medicine, searched for small genetic variants associated with ASD also using a genome-wide association approach.

She used a data set of 438 families with autistic children and then validated the findings with another data set of 487 families with autistic children.

"We found basically the same thing as the Nature paper,'' she says. In addition to multiple and rare gene variants, she concludes that part of "complex genetic architecture of autism involves common variation."

She calls the new research "the most significant finding to date, the most universal finding to date, that clearly shows common gene variants can play a role in giving someone a risk for autism."

Gene Variants and Autism: Interpretations

The new research still doesn't give autism researchers the whole picture, says Daniel Geschwind, MD, PhD, one of the principal investigators on the Nature research and director of the Center for Autism Research and Treatment, University of California Los Angeles.

But, he tells WebMD, "Over the last five years, there has been remarkable progress in autism genetics." That's primarily due to the relatively new technique of genome-wide association studies, he says.

"We know that rare genetic variation probably contributes more [to autism risk] than we thought it did," Geschwind says. "This study, looking at common variation, is more evidence that common variation is also involved."

Other research, including his own, has found that other common genetic variations also raises autism risk. "Each common variation is likely to be contributing a small amount," he says.

The new research, Geschwind says, is just the beginning. Information about involvement of specific genes will lead researchers to find the mechanism of the disease. "And the mechanism will lead us to treatment and maybe prevention."

Genetic Risks for Autism: Second Opinion

Together, the three studies provide very useful information, says Thomas Insel, MD, director of the National Institutes of Health's National Institute of Mental Health, who was not a co-author on any of the studies. The National Institutes of Health was one of numerous funding sources for the research.

The study findings don't immediately point to a specific cause or treatments, he says. "If you think about autism as a jigsaw puzzle with 500 pieces, each of these findings is an 'edge' piece." But many edge pieces are needed to make progress, he says.

"It would be a mistake for people to read this and think this is only about genetics," Insel says. "Almost everybody agrees that autism is a collection of different disorders. Some of them may be heavily genetic. But I think most experts would say the bulk of autism is the result of both genetic and environmental effects that are interacting in some way that we have yet to fully describe."

"This begins to fill out the genetic part of the equation."

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