JAMA: Two genetic tests, not one, could work better at diagnosing autism

Stephen Scherer

As researchers look for innovative ways to diagnose children with autism, scientists are revealing new evidence showing the efficacy of using two genetic tests together to screen for the disorder.

Stephen Scherer, director of the Centre for Applied Genomics and a professor at the Hospital for Sick Children in Toronto, and his colleagues compared chromosomal microarray analysis, a common genetic test, and whole-exome sequencing (WES), a more extensive test, to determine which was better at uncovering autism in 258 children with the disorder. The team also pitted the genetic tests against traditional behavioral evaluations to assess which was better at diagnosing the children.

Scientists found that while the tests on their own could detect autism at about the same rate--around 8% to 9%--together they could uncover nearly 16% of cases. But despite these results, more labs and clinicians are favoring WES, Scherer told Time Magazine. That's a problem, he added, because the two genetic tests pick up markers for different kinds of autism, potentially missing about half of the possible genetic predictors for the disorder. Researchers published their findings in a recent issue of the Journal of the American Medical Association (JAMA).

"We need to use both technologies now," Scherer said, as quoted by Time. "If we only used one, we would miss some important information."

The group also studied how nongenetic tests could complement genetic testing to diagnose autism. Scientists divided the children into three groups based on physical differences indicating the disorder and used techniques including brain scans to pinpoint signs of autism. The two genetic tests and the nongenetic screening method together diagnosed autism in 37.5% of cases in children with more physical abnormalities, suggesting that a three-pronged approach could be more effective.

But Scherer said in some cases, WES might be useful in screening for autism if a chromosomal test comes back negative, Time reports. And a behavioral test should still be the first step, followed by a chromosomal test that gives additional information about potential indicators of the disorder, he added.

- read the JAMA abstract
- here's the Time article