In autism, connections are important, new research suggests. Three genetic studies attempting to understand the disorder’s development point to molecules that form and maintain connections between cells.
“Of all the 20,000-plus genes [in the human genome], we’re down to a small family that keeps getting implicated,” says Thomas Insel, director of the National Institute of Mental Health, in Bethesda, Md.
Scientists previously thought it would be easy to identify common genes for common disorders. Given a large enough study size, statistical methods such as genome-wide associations would “pop out genes like olives out of a bottle,” says Steven Moldin, a human geneticist at the University of Southern California in Los Angeles. But until now, scientists have not been able to find a common genetic link among people with autism.
One of the new studies encompasses more than 14,000 people and has uncovered a variant found in about 65 percent of people with autism. More than half of people without autism or related disorders also have the variant, indicating that other genes and environmental factors are necessary to trigger autism. Still, the variant may account for up to 15 percent of autism cases, a team led by researchers at the Children’s Hospital of Philadelphia and the University of Pennsylvania School of Medicine, also in Philadelphia, reports online April 28 in Nature.