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Common genes greatest risk factor for autism

Genes that are common in the population carry the most genetic risk for autism, according to recent study findings published in Nature Genetics.

“Genetic variation likely accounts for roughly 60% of the liability for autism, with common variants comprising the bulk of its genetic architecture,” Joseph Buxbaum, PhD, of the Icahn School of Medicine at Mount Sinai, said in a press release. “Although each exerts just a tiny effect individually, these common variations in the genetic code add up to substantial impact, taken together.”

Buxbaum and colleagues evaluated about 3,000 people, including those with autism, to determine the effect of inheritability on autism risk. New statistical methods were used to sort out the inheritability of the disorder.

Researchers found that about 52% of autism risk was linked to common and rare inherited variation, whereas 2.6% were spontaneous mutations.

“From this study, we can see that genetics plays a major role in the development of autism compared to environmental risk factors, making autism more like height than we thought — many small risk factors add up, each pushing a person further out on the spectrum,” study researcher Kathryn Roeder, PhD, of Carnegie Mellon University, said in the release. “These findings could not have happened without statistics, and now we must build off of what we learned and use statistical approaches to determine where to put future resources, and decide what is the most beneficial direction to pursue to further pinpoint what causes autism.”

Researchers can now identify specific genetic risk factors detected in the sample. Although only a small number of spontaneous mutations were found, they lend important clues to understanding the molecular underpinnings of the disorder.

“Within a given family, the mutations could be a critical determinant that leads to the manifestation of [autism spectrum disorder] in a particular family member,” Buxbaum said. “The family may have common variation that puts it at risk, but if there is also a ‘de novo’ mutation on top of that, it could push an individual over the edge. So for many families, the interplay between common and spontaneous genetic factors could be the underlying genetic architecture of the disorder.”

Disclosure: The researchers report no relevant financial disclosures.