A Massive Search for Autism Genes Begins

New gene chips could finally bring clues to this complex disorder.

The hunt for the genetic basis of autism may soon be closing in on its elusive target. Scientists at 11 Boston-area institutions, including MIT and the Broad Institute, will use new tools to analyze DNA samples from thousands of autistic people and their families. It is expected to be the largest search to date for the genetic causes of autism and may yield candidate genes in as little as six months.

Identifying genetic variations that increase the risk for autism could lead to new treatments for the disorder. (Credit: Istockphoto.com/mevans)

"This project will allow us to study the genome with an unprecedented level of detail," says Mark Daly, a researcher at the Broad Institute who is participating in the project. "Once we have an understanding of the genes and causal pathways underlying the disease, we can focus [on] research and development of therapeutics for those genes."

Scientists know that autism, which occurs in about one in 166 children, has a genetic component; siblings of autistic people have a much higher chance of developing the disorder than the general population. But the disease probably has a number of causes, including environmental influences and multiple genes. As with other complex genetic diseases, pinpointing the genes that increase risk has been enormously difficult.

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Previous studies have identified large regions of the genome that appear to contain genetic variations linked to autism. That region might contain hundreds of genes, however, and the limits of DNA-analysis technology have made identifying the specific culprit a challenge. In such situations, scientists usually make a guess based on the known biology of the disease. "It's very frustrating," says Rudy Tanzi, a neurologist at Harvard Medical School and a collaborator on the project. "The odds are low that you've picked the right gene."

But scientists can now scan the genome much more thoroughly using newer varieties of gene chips, tiny glass slides coated with particular sequences of DNA that can identify sequences in a sample by binding to them. The latest chips can quickly detect more DNA sequences than ever before -- hundreds of thousands of them at a time. "Now we can find diamonds among the glass," says Tanzi.