MONDAY, Aug. 15 (HealthDay News) -- The sibling recurrence risk of autism spectrum disorders (ASD) among infants with an older affected sibling is almost 19 percent, and is significantly predicted by infant gender and having more than one affected sibling, according to a study published online Aug. 15 in Pediatrics.
Sally Ozonoff, Ph.D., from the University of California Davis Health System in Sacramento, and colleagues obtained an updated recurrence risk of ASD among 664 infants with an older affected biological sibling. Data were collected from the multisite international network Baby Siblings Research Consortium. All the participants were followed up from early in life to 36 months and were categorized into ASD and non-ASD outcome groups. The ASD outcome group included participants who scored above the ASD cutoff of the Autism Diagnostic Observation Schedule and received a clinical diagnosis from an expert clinician.
The investigators found that 132 infants met the ASD criteria, resulting in an estimated recurrence rate of 18.7 percent. Gender of the infant and presence of more than one affected sibling (multiplex family status) were significant predictors of ASD outcome. The risk of ASD increased 2.8-fold in male infants, and two-fold if there was more than one older affected sibling. The infant's age at enrollment, gender, functioning level of the infant's older sibling, and other demographic factors were not predictive of ASD outcome.
"The sibling recurrence rate of autism spectrum disorder is higher than suggested by previous estimates," the authors write.
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