August 18, 2011
Andrew Adesman, MD
About one in 110 US children has been diagnosed with an autism spectrum disorder (ASD), and children who have an older sibling diagnosed with ASD are more likely to receive that diagnosis, according to a study just published online by the journal Pediatrics.
Using data from 12 different sites internationally, this large, well-designed study of families with an older child with an autism spectrum disorder employed a systematic and rigorous approach to evaluating the recurrence risk for an autism spectrum disorder in subsequent children when evaluated at age 3.
This study found a higher than expected recurrence rate for an ASD. Whereas prior research has suggested that the recurrence rate for another child with an autism spectrum disorder ranges from 3 percent to 10 percent, this study suggests the overall recurrence rate is 18.7 percent. Recurrence risks were found to be especially high for boys and in families with more than one affected child. In this study, there was almost a three-fold greater risk for an ASD in later male children compared to female children (26.2 percent vs. 9.1 percent, respectively). In families with two or more older children, there was a much higher risk of recurrence if two older children had an ASD compared to households with only one affected older child (32.2 percent vs. 20.1 percent).
To the extent that recurrence risks were found to be higher than previously reported, these new findings must be rather sobering and disconcerting for parents who have one or more children with an ASD and who are considering having another child.
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