New research appears to confirm that environmental influences on genes, and not just gene mutations, play a role in the development of autism.
Previous research has suggested that gene mutations account for only about half of the risk for developing autism, the study authors pointed out.
Scientists know that men who are older than 40 are at greater risk for having a child with autism because of genetic mutations that accumulate over the years in sperm-making cells. Women who are 35 and older also face a greater chance for having a child with autism. The reason why, however, has been unclear.
In conducting the study, the researchers looked at environmental changes to genes that could help explain this increased risk, such as conditions in the mother’s uterus, stress and diet. These types of changes are called epigenetic changes.
The study, published online May 29 in the journal PLOS Genetics, involved 47 children with autism spectrum disorder (ASD) and 48 typically developing children of women aged 35 and older. The kids lived throughout the United States, as well as in Chile and Israel.
To look for differences in genes between the children, the researchers analyzed cells that lined their cheeks (the buccal epithelium).
“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,” study senior author Dr. John Greally, director of the Center for Epigenomics at Einstein, said in a news release.