a mother and childResearch into the causes of autism spectrum disorders (ASD) suggests that the interplay of genetic and environmental factors is responsible for the disorder. A study from Albert Einstein College of Medicine of Yeshiva University identified gene groups altered by environmental factors in children with autism. The findings may explain why autism seems to sometimes be caused by genetics, but sometimes caused by the environment.

The researchers evaluated genetic samples from 47 children with ASD and 48 typically developing children. All of the children were born to mothers aged 35 years or older. The children came from diverse backgrounds: there were a significant number of Hispanic and African American children and the children were from the United States, Israel, and Chile. To access the children’s genetic material, the researchers collected samples from of buccal epithelial cells, which are found in the lining of the cheek.

The researchers analyzed the cell samples, searching first for abnormal chromosome numbers or other chromosomal defects, since older mothers tend to have children with chromosomal abnormalities. Then, they looked for environmental, or epigenetic, differences. Epigenetics deals with heritable changes to genetic activity that are inherited, but not caused by changes in the DNA sequence. For children with autism, the most likely cause of epigenetic changes are the environmental conditions that a pregnant mother is subjected to.

They found two epigenetically distinctive groups among the ASD children, but the epigenetic markers were not found in the typically developing children. This indicates that environmental factors were the primary causes of autism for the children. These distinctive gene groups are involved in nerve transmission in the brain. Other studies have identified these genes as playing a role in ASD.

“Genes interact with each other to create molecular pathways that carry out important functions. Our findings suggest that, at least in some individuals with 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,” stated Dr. Greally, senior author of the study and director for the Center for Epigenomics at the Children’s Hospital at Montefiore.
This research is published in the journal PLOS Genetics.

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