Jul 13, 2017

What the genetics of eye contact tell us about autism

Washington University School of Medicine

Scientists say they can show that how a child looks at the world is directly and fundamentally influenced by his or her genes — a finding that could reverberate in the autistic world, according to a study published in Nature Wednesday. Warren Jones, study author and director of research at the Marcus Autism Center, says:

"That's not a metaphorical statement: These results show that a child's genome influences how and when she moves her eyes, the direction in which she moves her eyes, and the content she spends time looking at. The implications of that are amazing: How a child looks at the world is how she learns about the world, and this study shows that how she looks at the world is fundamentally influenced by her genes. A child's worldview is shaped by her genes."

Why this is important: The study suggests common behavior in autism — particularly reduced attention to other people's eyes — is directly influenced by a child's genetic makeup.

Study details: The scientists studied 338 children total, grouped by their genetic similarities (identical twins, fraternal twins, unrelated, and those diagnosed with autism). They used eye-tracking technology to analyze the movement of each child's eyes while they watched videos of commonly experienced childhood scenes (such as children at play or a maternal figure). The scientists tracked their eyes and measured the time and location to see what percentage of time each child looked at each region. Follow-up tests were run 15 months later to confirm continued genetic influence.

The findings:

Children not diagnosed with autism spectrum disorder:

  • 82 identical twins (sharing 100% genome) had a 91% match (mirroring each other's behavior to within as little as 17 milliseconds) for the eyes and 86% match for looking at the mouth.
  • 84 non-identical twins (sharing roughly 50% genome) showed a 35% match for the eyes and 44% for the mouth.
  • 84 unrelated children (when matched on age and sex) had a 16% match for the eyes and 13% for the mouth.
  • Those same 84 unrelated children had a 0% match when randomly assigned together for both eyes and mouth.

For the 88 toddlers diagnosed with ASD, the scientists found:

  • The children spent significantly less time looking at faces and more time looking at objects. Jones said they looked at objects almost twice as much as typical children, and at faces about half as much time as typical children look.

Reaction to the findings: "That is fantastically significant data," says Judith Miles, a child health geneticist at the Thompson Center for Autism and Neurodevelopmental Disorders who was not part of this study. She says it is important because it first determined that there is a genomic biomarker for eye-looking and then showed that children with ASD had reduced eye movement for both eye and mouth-looking gazes, which are the social engagement behaviors shown to be influenced by genetics.

Yes, but: Just because genetics may be a factor in some behavior shown by autistic children does not mean that parents cannot play a role in helping their child overcome autistic behaviors. "Early intervention is key," Jones says. "It's important for parents to know that just because we determine that a behavior is heavily influenced by a child's genes doesn't mean that it can't be changed. Genes are the ingredients but it's not a predetermined outcome; genes still interact with environment and learning."

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