December 09, 2019
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DNA testing may predict ASD in siblings of individuals with the disorder

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Stephen W. Scherer

DNA testing of siblings of individuals with autism spectrum disorder may help predict a future diagnosis, according to findings published in Nature Communications.

“In families having a history of autism, specific genetic factors known as copy number variations (CNVs), if present in their next born child, can predict autism with over 85% accuracy,” Stephen W. Scherer, PhD, FRSC, of The Hospital for Sick Children in Toronto, told Healio Psychiatry. “The challenge is still that the type of autism that arises could be quite variable in symptoms and severity, but this finding is an important start for the development of early pre-symptomatic biomarkers which can help in early identification enabling intervention.”

According to Scherer and colleagues, subclinical traits related to ASD show familial clustering. A substantial portion of familial liability is attributed to genetic factors, they noted. In the present study, they analyzed the Baby Siblings Research Consortium, which encompasses 288 infant siblings whose family history is associated with a higher probability of developing ASD. From this, they determined clinical microarray findings for 253 longitudinally phenotyped ASD families. A total of 103 siblings (35.8%) by age 3 were diagnosed with ASD and 54 (18.8%) were developing atypically. Further, 13 siblings had CNVs involving ASD-relevant genes — six with ASD, five atypically developing and two typically developing. These CNVs in a sibling had a positive predictive value for ASD or atypical development of 0.83 — the Simons Simplex Collection of ASD families shows similar values, the researchers noted. They highlighted that common genetic variants may also contribute to ASD, according to polygenic risk analyses.

“The earlier that autism can be diagnosed, the better the chance for a positive outcome enabled by early behavioral and speech and language training,” Scherer said. “The families studied already had one child with autism, and the CNV markers used highlighted that autism would present in subsequent siblings about 7% of the time.” – by Joe Gramigna

Disclosures: Scherer reports serving on Scientific Advisory Committees for Population Bio and Deep Genomics, and The Hospital for Sick Children has license software code he co-developed to Lineagen.