Children Whose Siblings Have Autism Much Likelier To Have It Too

Siblings more likely to have autism too.

Parents’ confusion and concerns about autism may widen even further with a new study, published online today in the journal Pediatrics, which finds that one in five children in families with one child already diagnosed with autism spectrum disorders (ASD) will develop the illnesses as well. Researchers found that children who have an older sibling with an ASD are twice as likely than was previously believed to have the disorders themselves.

In the past, the recurrence rate of autism spectrum disorders in families with one diagnosed child was thought to be between three and ten percent.  The new study, conducted by researchers from the US and Canada who are part of the High Risk Baby Sibling Research Consortium, found a recurrence rate of 18.7 percent.  If two or more children in the family have been diagnosed with autism spectrum disorders, then the likelihood that future children will have the same diagnosis jumps to 32 percent.

The study also aimed to identify which factors do not contribute to a child being diagnosed with ASDs.  The American Academy of Pediatrics reports “neither parental age, gender of the sibling, functioning of the sibling, or birth order was a significant factor of ASD outcome.”

While this news is likely to be of serious concern to many parents who already have one child with ASD, Sally Ozonoff, the study’s lead author and a psychiatry professor at the Mind Institute at the University of California at Davis, says the study is not a guarantee that future children will have the same fate.  In an interview with the Associated Press, she noted that ” … 80 percent of the siblings studied did not develop autism, and that the prevalence rate was an average.  It may be different for each family, depending on other risk factors they may face.”

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