According to the Autism Society, the prevalence of autism in US children increased by 119.4 percent from 2000 (1 in 150) to 2010 (1 in 68). This makes autism the fastest-growing developmental disability.
In a new study, Israeli researchers at Ben-Gurion University of the Negev say they have taken “a step closer” to understanding the genetic basis of autism, which they hope will lead to earlier diagnosis of Autism Spectrum Disorder (ASD).
Dr. Idan Menashe, Mr. 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.
A unique signature
Among the distinct characteristics of autism genes is their exceptional genomic length, which is even longer than other brain-expressed genes of closely related diseases such as Alzheimer’s disease and schizophrenia. Additionally, the authors found a unique genomic signature in these genes that was shaped by negative selection, 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. Such a mechanism could explain the presence of autism in the human population. However, no indications of positive selection acting on autism genes were found. Thus, autism susceptibility mutations are maintained in the human genome probably because they cause the disorder only in combination with other genetic and/or non-genetic factors.
Finally, the authors used the unique genomic characteristics of 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. These findings broaden our understanding about the genetic mechanisms that are involved in autism, and provide new tools for the discovery of new candidate genes.
“A step closer”
“We are a step closer to understanding the genes associated with autism and understanding the biological process that is involved in the disease,” Menashe told The Times of Israel. “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.”