Genetics play a big part in the way children see the world, according to new research from the Washington University School of Medicine in St. Louis and Emory University School of Medicine in Atlanta.
This discovery brings new data and details in understanding autism spectrum disorder. More specifically, the St. Louis and Emory study which was published online July 12 in the journal Nature found that the moment-to-moment movements of children's eyes as they seek visual information about their environment are abnormal in autism and under stringent genetic control in all children.
Lead author John N. Constantino, MD, the Blanche F. Ittleson Professor of Psychiatry and Pediatrics at Washington University, states that, "these new findings demonstrate a specific mechanism by which genes can modify a child's life experience. Two children in the same room, for example, can have completely different social experiences if one carries an inherited tendency to focus on objects while the other looks at faces and these differences can play out repeatedly as the brain develops early in childhood."Dr. Constantino also said "Now that we know that social visual orientation is heavily influenced by genetic factors, we have a new way to trace the direct effects of genetic factors on early social development, and to design interventions to ensure that children at risk for autism acquire the social environmental inputs they need to grow and develop normally."
There were 338 toddlers between 18 and 24 months old were studied using an Emory developed eye-tracking technology. The technology allows researchers to follow a young children’s visual orientation to eyes, faces, or objects while the children looked at videos with people interacting.
The children were a group of twins: 41 pairs of identical twins and 42 pairs of fraternal twins. Identical twins share 100% of their DNA, while fraternal twins share 50% give or take. On top of that researchers studied 88 children who were diagnosed with autism spectrum disorder and 84 unrelated children.
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Warren R. Jones, Ph.D.D, and Ami Klin, Ph.D., of Emory University School of Medicine and Constantino studied the eye-tracking data. Each twin was tested independently, at different times, without the other twin present.
The identical twins were almost exactly the same in the time they spent looking at another person’s eyes, however, the fraternal twins eye movements in one twin accounted for less than 10 percent of the variation in the eye movements of their co-twin. Identical twins also were more likely to move their eyes at the same moments in time, in the same directions, toward the same locations and the same content, mirroring one another’s behavior to within as little as 17 milliseconds. However, with the fraternal twins eye movements in one twin accounted for less than 10 percent of the variation in the eye movements of his or her co-twin. Identical twins also were more likely to move their eyes at the same moments in time, in the same directions, toward the same locations and the same content, mirroring one another's behavior to within as little as 17 milliseconds. When evaluated together the findings tell of a strong link between genetics and visual behavior.
Constantino, who also directs the William Greenleaf Eliot Division of Child and Adolescent Psychiatry at Washington University, said "the moment-to-moment match in the timing and direction of gaze shifts for identical twins was stunning and inferred a very precise level of genetic control." he also stated "We have spent years studying the transmission of inherited susceptibility to autism in families, and it now appears that by tracking eye movements in infancy, we can identify a key factor linked to genetic risk for the disorder that is present long before we can make a clinical diagnosis of autism."
A year later the same twins were tested again and identical twins pretty much stayed the same in where they looked while the fraternal sets attained more of a difference from the original study.
Lisa Gilotty, PhD, chief of the Research Program on Autism Spectrum Disorders at the National Institute of Mental Health, which provided support for the study in tandem with the Eunice Kennedy Shriver Institute of Child Health and Human Development said "Studies like this one break new ground in our understanding of autism spectrum disorder: Establishing a direct connection between the behavioral symptoms of autism and underlying genetic factors is a critical step on the path to new treatments."
Autism spectrum disorder is a lifelong condition that affects about 1 in 68 children in the United States and it is widely known the be genetic.