Study into the Genetics of Autism Offers New Clues, as well as More Questions

A new study into the 651 genes associated with autism has been published in the medical research journal Behavior Genetics. The findings of the study, conducted by researchers at Ben-Gurion University of the Negev (BGU), lays new groundwork for understanding the biological processes involved in the condition, one that now affects one in fifty children in the United States, according to the Center for Disease Control.

“We are now a step closer to understanding the genes associated with autism and understanding the biological process involved in the disease,” explains Dr. Idan Menashe, a member of the BGU Department of Public Health in the Faculty of Health Sciences. “This study gives us a tool to help identify additional autism genes using the genetic signature we found. From there, we hope to be able to diagnose autism earlier.”

One unexpected aspect of genes associated with autism spectrum disorder (ASD) is their exceptional genomic length — 65 percent longer than the genes of other related diseases, such as Alzheimer’s and schizophrenia. The genes were also found to have evolved from a process called negative selection: this is an evolutionary process where disruptive mutations are negated, and wind up being removed from the gene pool.

But while looking for evidence of the effects of positive selection, a process where a trait spreads through the population, Dr. Menashe says they found that ASD-linked genes did not appear to have been formed this way:

“While this kind of mechanism could explain the prevalence of autism in the human population, we found no indications of positive selection acting on autism genes. Thus, while autism susceptibility mutations are in the human genome, they only present as an autism disorder when combined with other genetic, non-genetic or environmental factors.

“Our findings suggest that ASD genes have evolved under complex evolutionary forces, which have left a unique signature that can be used to identify new ASD candidate genes.”