Siblings of Children with Autism Merit a Closer Look

Registry study finds elevated risk of autism, related problems

Even if they don’t have autism themselves, sisters and brothers of children with autism spectrum disorder (ASD) may carry traits that need attention. So suggests new research from Cleveland Clinic Children’s Center for Autism.

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Thomas Frazier

Thomas Frazier, PhD

“In families that are affected by autism, you want to pay close attention to the siblings and make sure they’re not affected by autism or something related,” says Center for Autism Director Thomas Frazier, PhD, who led the new study, published October 27 in Molecular Autism. He collaborated with Cleveland Clinic Genomic Medicine Institute Chair Charis Eng, MD, PhD, and colleagues from several other U.S. and Canadian institutions.

Three high-risk family scenarios identified

Among 2,577 families with at least one child with ASD, the researchers identified three high-risk family scenarios:

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  • Having more than one child with autism
  • Having a female child with autism
  • Having a history of language delay or autistic-like speech patterns in non-ASD siblings

Siblings who don’t have ASD but whose families fit one of these three situations merit special attention for several reasons, Dr. Frazier says. “These sibs really need to be looked after carefully because they have elevated traits and may be at risk of passing along autism to their kids when they’re older,” he explains. “And even if they don’t have autism, they may have other diagnoses like attention deficit hyperactivity disorder or anxiety. Or they may just have problems that require specific treatment, like speech therapy or occupational therapy.”

More findings from the Internet-based registry analysis

The study data came from the Interactive Autism Network, an Internet-based registry for families with one or more children with ASD. In all, there were 2,262 families with one child diagnosed with ASD and 315 families with more than one. At least one female with ASD was present in 459 of the families.

Among the findings:

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  • Higher levels of autistic symptoms were seen among siblings of children with autism from families with more than one ASD-diagnosed child relative to families with just one child with ASD. There has been debate as to whether at least some of these siblings might just have a milder form of autism, but Dr. Frazier says some of his prior data show that “they don’t actually have autism — they just have elevated traits.”
  • Among the non-ASD siblings, higher levels of autistic symptoms, language delay and autistic speech patterns were significantly associated with motor delay and older age at first independent walking and first meaningful-phrase speech.
  • Siblings from families in which a female child has ASD had higher autism symptom levels than did those from families in which the ASD-diagnosed children are males. “We think that’s because to be a female with autism you have to have additional genetic hits,” Dr. Frazier explains. “So undiagnosed sibs are more likely to have elevated traits in those families.”

A more comprehensive care model for ASD-affected families

Cleveland Clinic Children’s Center for Autism provides comprehensive care for ASD-diagnosed children as well as their non-ASD siblings with other needs, but that is not the case everywhere, Dr. Frazier notes.

“I think as we’re learning about these subtle difficulties that kids have, it’s important not to forget about them and focus only on those with more obvious difficulties,” he says. “We need better treatment services both for people with autism and for their siblings who may require other forms of care.”