Researchers found that a set of 32 RNAs in saliva could eventually help doctors diagnose autism spectrum disorder earlier. While ASD diagnosis is possible as early as 24 months old, most diagnoses come around the fourth year of life. File photo by OndroM/Shutterstock

Nov. 12 (UPI) -- Scientists have developed a way to pinpoint autism in children at earlier ages by testing their saliva, avoiding more invasive means of detection.

Researchers found a set of 32 RNA factors in saliva that can accurately distinguish children with autism spectrum disorder, or ASD, from children without it. Based on their researcher, they say the factors could be used to develop an objective biomarker-based test.


Steven Hicks, of the Pennsylvania State College of Medicine, and Frank Middleton, of SUNY Upstate Medical University, along with scientists from Quadrant Biosciences, published a study in Frontiers in Genetics outlining the method.

The researchers analyzed the RNA of more than 450 children between the ages of 18 months and 6 years old. With 85 percent accuracy, they found differences in 238 children with autism spectrum disorder, or ASD, from 218 children showing normal typical developmental delay.

The researchers used comprehensive next-generation sequencing to measure RNAs in the saliva, using a machine-learning algorithm for the first 372 children. They validated the remaining 84 children's samples without the machine learning.

Levels of human and bacterial RNAs were measured in the saliva samples using comprehensive next-generation sequencing. The top RNAs were identified using robust machine-learning algorithms from the first 372 children and then validated in the remaining 84 samples that were not used in the machine learning.

This method gave the researchers a way to more widely investigate the genomic, physiologic, microbiome and environmental factors that cause ASD.

"Growing evidence suggests that autism arises from interactions between a child's genes and the environment," Hicks said in a press release. "This study measured factors that may control interactions between genes and the environment, especially the microbiome."

This new screening method gives researchers and parents a more accurate way to assess autism in children. Current screening uses the Modified Checklist for Autism in Toddlers Revised, or MCHAT-R, a parent-based test that generally takes over a year to render results and often turns up false positives.

In the U.S., the average age for ASD diagnosis is older than four-years-old. So the earlier the diagnosis, the sooner experts can deliver intensive treatment, which can improve autism symptoms in children.

"The ability to accurately discriminate between children with autism and their peers with non-ASD developmental delay is of paramount importance in the field," Middleton said.

"While the algorithm is not designed as a screening tool, it can provide valuable information in children with a positive MCHAT-R screen, over 80 percent of whom will not have ASD. In this way, it can be used to prioritize specialist referral or to provide an objective aid to an autism diagnosis," Middleton said.