Researchers at Ben-Gurion University of the Negev say they have taken “a step closer” to understanding the genetic basis of autism.
Dr. Idan Menashe and his colleagues, Erez Tsur and Prof. Michael Friger, studied the sequences of over 650 genes that are associated with autism and discovered characteristics that distinguish them from other genes in the genome. Their research was recently published in Behavior Genetics.
The researchers found that autism genes have the distinct characteristic of being exceptionally long, longer than other brain genes including those of closely related illnesses such as Alzheimer’s disease and schizophrenia.
Additionally, the researchers found that the negative selection process in these genes was more active than in other genes. Negative selection is an evolutionary process that removes disruptive mutations from genes over generations.
Menashe and his colleagues also searched for evidence of positive selection in these genes — to see if the body believes that autism could be actually beneficial to the body and therefore justifies the presence of autism in the human population. However, no indications of positive selection acting on autism genes were found.
Thus, the researchers believe that autism susceptibility mutations manage to survive in the human genome not because of a faulty negative selection process or the presence of a positive selection process. Rather, they probably survive because autism is created not just in the gene but in combination with other genetic and/or non-genetic or environmental factors, like the age of the mother or other external reasons.
The researchers also used the unique genomic characteristics found in the autism genes to identify additional candidate genes for the disorder. They showed that this evolutionary signature is highly efficient in capturing well-established autism genes, they said in a statement. These findings broaden the understanding about the genetic mechanisms that are involved in autism and provide new tools for the discovery of new candidate genes.
“We are a step closer to understanding the genes associated with autism and understanding the biological process that is involved in the disease,” said Menashe in a phone interview. “This study gives us a tool to help identify additional autism genes, using the genetic signature we have found, and from there hopefully to be able to diagnose autism earlier.”
Menashe and Tsur are members of the Department of Public Health, the Faculty of Health Sciences, and the Zlotowski Center for Neuroscience. Friger is a member of the Department of Public Health.