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Autism spectrum disorder

New research has found that testing the DNA of siblings of individuals with autism spectrum disorder (ASD) may be predictive of a future diagnosis, even if symptoms aren’t apparent.

ASD refers to a group of neurodevelopmental conditions resulting in challenges related to communication, social understanding and behaviour.

Studies show families who have a child with ASD have a 6.9% to 19.5% chance of another child having ASD and a 30% to 40% chance of another child having atypical development.

Stephen Scherer, principal investigator of the study, said: “Genetic factors are the most likely reason we see a clustering of ASD-related traits in families.

“We wanted to investigate the possible benefits of genetic testing for infants whose older sibling had already been diagnosed with ASD. If we can identify those children early, we may be able to enrol them earlier in therapies.”

The researchers looked for the presence of genetic alterations that have been linked to ASD called copy number variations (CNVs) in over 288 infant siblings from 253 families.

By age three, 157 siblings were either diagnosed with ASD or developing atypically. DNA testing revealed CNVs in genes relevant to ASD in 11 (7%) of the 157 siblings who were eventually diagnosed.

The study found that the presence of an ASD-relevant CNV in a sibling had a high likelihood of predicting a future diagnosis of ASD or atypical development. This is the first time the predictive value of CNVs have been quantified in determining these diagnoses.

Image credit | iStock

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