Testing for Autism in Toddlers
A panel of genes expressed in blood can distinguish toddlers who will later be diagnosed with autism from those without the disorder 83 percent of the time.
The finding, reported 4 March in JAMA Psychiatry, suggests that signaling pathways involved in inflammation, immune responses and protein synthesis are at play in autism. It also hints at the still-distant possibility of a blood test for the disorder.
Others are more equivocal about the promise of the approach for predicting autism. “This study tells us that there’s a real signal there, but by itself it may not be good enough to make a diagnosis, ” says Isaac Kohane, professor of pediatrics and health sciences technology at Boston Children’s Hospital, who was not involved in the study. “I think the most important contribution of this study is to cause us to focus even more tightly on these particular sets of pathways, to understand what’s causing them.”
Clinicians currently rely on a battery of behavioral evaluations to diagnose autism. But the average age of diagnosis hovers stubbornly around 4 years, long after symptoms emerge and behavioral interventions are believed to be most effective.
“What we’re looking for is something that might be an earlier, more objective indicator, ” Courchesne says. “It’s a whole line of research aimed at identifying babies at risk for autism to get them into evaluation and treatment at early ages.”
Courchesne and his team measured gene expression in blood samples from 142 boys between the ages of 1 and 4. The researchers selected the boys from community pediatric clinics that had flagged them using the Infant-Toddler Checklist — a 24-item screening test for developmental disorders.
Of the 142 boys, 87 were later diagnosed with autism. The remaining 55, including 14 with developmental delays, made up the control group.
The researchers found that 2, 765 genes were expressed at different levels in the boys with autism than in the controls. The genes cluster into 12 distinct networks, dubbed ‘modules.’ Each module consists of genes that are turned on or off at the same time and tend to have a shared biological function.