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Younger siblings of those with ASDs at increased risk for recurrence
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Siblings of those with autism spectrum disorders are at increased risk for the disorders themselves compared with siblings of those without autism spectrum disorders, according to recent study findings published in JAMA Pediatrics.
“To date, this is the first population-based study to examine the recurrence risk for autism spectrum disorders, including time trends, and the first study to consider the [autism spectrum disorders] recurrence risk for full- and half-siblings,” Therese K. Grønborg, MSc, of Aarhus University in Denmark, and colleagues wrote.
The population-based cohort study included all children born in Denmark from 1980 to 2004. All participants were followed up until 2010.
Researchers found that, overall, the recurrence risk for autism spectrum disorders (ASDs) was 6.9 (95% CI, 6.1-7.8), and similar risks were found between maternal and paternal full-siblings. For half-siblings, relative recurrence risks were 2.4 (95% CI, 1.4-4.1) for maternal and 1.5 (95% CI, 0.7-3.4) for paternal.
Participants who have an older sibling with an ASD are seven times more likely to have an ASD compared with participants whose older sibling did not have an ASD.
“Although the results from our comparison of recurrence in full- and half-siblings support the role of genetics in ASDs, the significant recurrence in maternal half-siblings may support the idea of a contributing role of factors associated with pregnancy and the maternal intrauterine environment,” researchers wrote. “Finally, the lack of a time trend in the relative recurrence risk in our data suggests that the likely combination of genetic and environmental factors contributes to the risk for ASD recurrence in siblings or that the risk of recurrence because of such factors has not been affected by the rise in ASD prevalence.”
Disclosure: The study was funded in part by Aarhus University.
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