Environmental Factors Increase Autism Risk in Some Children

A new study shows that environmental factors increase autism risk in few children, who are born to mothers aged above 35 years.

The study, conducted by researchers at Yeshiva University's Albert Einstein College of Medicine, found that in some cases, environment - not genetics, might be linked to autism.

Autism Spectrum Disorders are a group of developmental disorders that lead to significant social, communication and behavioral challenges. Estimates from CDC's Autism and Developmental Disabilities Monitoring (ADDM) Network suggest that one in every 68 children in the U.S. have ASD.

Genetic factors account for about half of all autism diagnosis. Other researchers have attributed the other half to non-genetic factors. In the present study, researchers looked at both genetic and non-genetic factors to find why older mothers have higher chances of having a baby with autism.

"We hypothesized that whatever influences lead to ASD in children of older women probably are already present in the reproductive cells that produce the embryo or during the very earliest stages of embryonic development-in cells that give rise to both the buccal epithelium and the brain," said John Greally, the study's senior author, according to a news release. "This would mean that whatever abnormalities we found in the cheek cells of children with ASD versus TD children should exist in their brain cells as well."

The study included 47 children with ASD and 48 typically developing (TD). The study included children belonging to Hispanic and African-American ethnicities. The team then obtained cheek cells to see if there was any genetic defect.

The team didn't find chromosomal defects in the genes. But, when they looked into environmental factors, they found clear difference between typical children and those with ASD, Medical Daily reported.

The team found two groups of genes that were epigenetically distinctive in children with ASD, according to a news release. These genes code for proteins that are associated with brain abnormalities seen in autistic children. But, these epigenetic changes were seen only in a subset of the ASD children. Epigenetics refers to the several chemical reactions that activate or deactivate genes.

"Genes interact with each other to create molecular pathways that carry out important functions," said Dr. Greally. "Our findings suggest that, at least in some individuals with an ASD, the same pathways in the brain seem to hit by both mutations and epigenetic changes. So the severity of someone's ASD may depend on whether or not a gene mutation is accompanied by epigenetic alterations to related genes."

The study is published in the journal PLOS One.