Researchers make discovery while searching for epigenetic diagnostic biomarkers for autism

SYRACUSE, N.Y. /PRNewswire/ -- Scientists have discovered certain molecules in the saliva that not only differentiate children with autism spectrum disorder (ASD), but appear to correlate with specific autism traits.  Although the study primarily assessed the ability of specific microRNA ("miRNA") molecules to accurately differentiate children with autism, the researchers made the additional discovery that levels of certain salivary miRNAs were associated with specific ASD behaviors. These insights have important implications in providing an objective, molecular biomarker for autism diagnosis or therapeutic monitoring.

The paper, "Saliva microRNA Differentiates Children With Autism From Peers With Typical and Atypical Development" was published online by the Journal of the American Academy of Child and Adolescent Psychiatry by researchers Steven Hicks, M.D., Ph.D., of the Pennsylvania State College of Medicine and Frank Middleton, Ph.D., of SUNY Upstate Medical University, in collaboration with scientists from Quadrant Biosciences Inc.

The multi-center, case-control study collected saliva samples from 443 children, ages 2-6 years, who were receiving well child or developmental specialist care at the Penn State College of Medicine, or SUNY Upstate Medical University. The authors compared saliva samples from 225 children with ASD to 218 children without ASD (including 84 children with developmental delay and 134 with typical development). Levels of miRNAs were measured in the saliva samples using comprehensive next-generation sequencing.  Additionally, extensive medical and demographic data were collected, and behavioral assessment was performed using the Vineland Adaptive Behavior Scales and the Autism Diagnostic Observation Schedule.

miRNA as Differentiators of ASD

The first key finding was confirmation that miRNAs in the saliva had predictive value for ASD diagnosis. Specifically, a panel of four miRNAs was able to differentiate children with autism from their peers with typical development, as well as those with non-autism developmental delays. This confirmed the results of an earlier pilot study, supporting the feasibility of an objective, molecular test for autism. And, as Dr. Middleton points out, this could have a positive impact on the current ASD diagnostic pathway.  "The ability to accurately differentiate between children with autism and their peers with non-ASD developmental delay is of paramount importance in the field, as it can be used to prioritize specialist referral or to provide an objective aid to an autism diagnosis."

However, Middleton also noted that while this approach has promise, improving the specificity of the test would be essential for clinical use. "Instead," he explains, "a 'poly-omic' approach, using several classes of molecules, is likely necessary to identify autism spectrum disorder."  Indeed, other research published recently by this same group ("Validation of a Salivary RNA Test for Childhood Autism Spectrum Disorder published recently in the journal Frontiers in Genetics") confirmed the superiority of such a poly-omic approach as a diagnostic tool for ASD. Moreover, it represents the foundational science behind a new epigenetic saliva test for ASD coming to market shortly.

Correlation to ASD Phenotypes

Another potentially groundbreaking insight was that levels of specific salivary miRNAs were associated with children's adaptive and social abilities. For instance, levels of eight saliva miRNAs were significantly associated with the severity of a child's social deficits, while levels of ten miRNAs were associated with frequency of a child's repetitive behaviors (as measured with standard autism assessments).

Dr. Hicks pointed out the significant clinical benefit this discovery may hold in the future. "This large study allowed us to begin examining relationships between specific microRNAs and specific autism symptoms. These findings will need to be validated in further studies, but they provide early evidence that saliva miRNA levels may eventually be used for prognosis, or even assess a child's biologic response to behavioral interventions." Currently there are no objective, biologic tests to predict the extent to which a child with autism will improve with therapy, or to determine if therapy is working.   

Establishing an SOP for Future Autism Epigenetic Research

Finally, the study helped to identify the multitude of factors that influence childhood miRNA expression, including RNA quality, time of collection, sex, and age.  According to Dr. Middleton, "accounting for the potential influences of different subject and sample parameters on the sequencing data outcome is crucial for ongoing and future efforts to develop reliable RNA-based biomarkers for autism or other disorders."

Richard Uhlig, CEO of Quadrant Biosciences, and the developer of an autism saliva test based on this research, agreed. "Thanks to this research, these critical elements have now been incorporated into the standard operating procedure for the research methodology behind our Clarifi autism saliva test, and all future research projects at Quadrant."

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This study was funded by a research agreement with Quadrant Biosciences Inc. (QB; formerly Motion Intelligence), the State University of New York Upstate Medical University, the Penn State College of Medicine, the Kirson-Kolodner-Fedder Charitable Foundation, and the National Institutes of Health (R41MH111347).