For the study, scientists analyzed data on gene expression produced by BrainSpan, a project designed to create an atlas of the human brain.
The findings revealed that particular neural circuits were affected by genes that carry a risk for autism, as well as “when, where and in what cell types those genes exert their effects on the developing human brain and lead to autism spectrum disorders,” according to the report, published in the journal Cell.
The researchers investigated nine genes already linked to autism and discovered two common “molecular crossroads.” The first was a cell type that becomes active three to five months after conception, and the second was the mid-fetal frontal cortex—responsible for cognition, language and complex motor behaviors, according to the report.
How the connection works, however, is still not clear.
“The brain is extraordinarily complicated, but this approach gives us a way to pinpoint some of the mechanisms that contribute to a host of complex brain disorders,” such as schizophrenia, said co-senior author Nenad Sestan, Ph.D., professor of neurobiology and investigator for the Kavli Institute for Neuroscience at Yale.
“We know now that we may not have to treat the whole brain, that changes related to mutations in autism-risk genes may affect particular neural circuits at specific places at specific times,” said Sestan.
Autism has been difficult to link to specific genes, since hundreds of genes have been found to have a relationship to the autism spectrum.
“The task of searching for a cause for the disorder is the scientific equivalent of trying to reach an unknown town in Maine knowing only that you started from a street in San Diego,” the report noted.
Autism spectrum disorder (ASD) is a range of complex neurodevelopment disorders, characterized by social impairments, communication difficulties, and restricted, repetitive, and stereotyped patterns of behavior, according to the National Institute of Neurological Disorders and Stroke.
Experts estimate that 1 out of 88 children age 8 will have an ASD with males being four times more likely to have an ASD than females.