Children with autism, as a group, are genetically more similar to one another than to a group of their unaffected siblings, a new study suggests1. The findings support the notion that people with the condition share common inherited variants that boost autism risk.
Studies comparing people who have autism with unrelated controls suggest common variants can contribute as much as 49 percent to autism risk. But ethnic differences between the two groups in previous studies may have skewed this estimate too high, says Michael Wigler, professor at Cold Spring Harbor Laboratory in New York.
In the new study, Wigler and his team compared people with autism with their unaffected siblings, who have similar genetic backgrounds. They found strong evidence that variants of small effect that are passed down for generations contribute to autism risk, Wigler says. “It was significant at a very substantial level,” he says.
The study does not provide an estimate of how much common variants contribute to autism risk. But it adds to mounting evidence that these variants play an important role, says David Goldstein, director of the Institute for Genomic Medicine at Columbia University in New York, who was not involved in the study.
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