In the world's largest DNA scan for autism, US scientists have uncovered a new gene variant, called CDH10, which is highly common in children suffering from the disorder.
In partnership with 30 research institutions across the US, scientists scrutinized the activity of CDH10 and found that it is most active in key regions that support language, speech and interpreting social behaviour.
The two findings suggest that CDH10 plays a critical role in shaping the developing brain and may contribute to a prenatal risk of autism.
"While this gene variant is common in the general population, we discovered that it occurs about 20 percent more often in children with autism. A major change like this in the genetic code is too common to be a simple mutation - it is a risk factor in the origin of the disease," Nature quoted study author Dr. Daniel Geschwind, director of the UCLA Center for Autism Treatment and Research, as saying.
Using the largest population sample till date, the scientists systematically scanned the DNA of 3,100 individuals from 780 families nationwide. Each family had at least two autistic children.
The scan linked autism to a specific region of chromosome 5, which was previously named as a hub for genetic variations linked to higher autism risk.
To verify the findings, researchers conducted a second scan on the DNA of 1,200 individuals from families affected by autism, as well as nearly 6,500 healthy controls. All participants shared European ancestry.
The scientists evaluated the relationship of more than half a million gene variants to autism and consistently discovered six changes that occurred more frequently in autistic children than in the control group.
It was found that the variants sat on chromosome 5 between two genes, CDH9 and CDH10.
In the second half of the study, the UCLA team looked at the two genes' presence in the developing human brain.
While CDH9's presence appeared minimal, the scientists discovered that CDH10 was most active in the fetal brain's frontal cortex, a region critical to language, social behaviour and complex thought processes such as judgment.
"This is a landmark finding. It's no coincidence that a gene linked to autism has a higher concentration in key brain regions that regulate speech and the ability to interpret social interaction. Our research suggests that CDH10 is switched on at a very early stage and plays an important role in regulating the developing brain. This prenatal activity somehow makes the infant more susceptible to autism," said Geschwind.
He claimed that by influencing the development of important brain structures, CDH10 provides a tangible link between genes, brain circuitry and a child's future behaviour.
The study is published in the advance online edition of the journal Nature.