In “a culmination of decades of cognitive behavioural work,” scientists have found the connection between an autism-risk gene and the part of the brain linked to autism.

“We believe we’re the first to look at a system-wide network in association with a gene,” Dr. Ashley Scott-Van Zeeland told the Star Wednesday. “This study provides that link.”

Discovering the link started with genetic variations in CNTNAP2 (fondly called “catnap2” by scientists), which have been associated with autism, specific language impairment and other neurological disorders.

“Everyone has two copies of the gene. Even if you just carry one copy of the version that is at risk for autism, it shows up in what the middle frontal part of the brain is hooked up to.”

The frontal lobes are responsible for “higher-order cognitive functions” such as decision-making, cognitive control and abstraction, as well as speech and language.

The brain mappings for children with the “risk variant” of CNTNAP2 genes, showed up as a stronger left connectivity in the frontal lobes and weaker long-range connections in the back of the brain.

“We tested to see if they are truly different,” said Scott-Van Zeeland. “The risk carriers have this over-connectivity in the front and reduced in the back.”

When that statistical evidence unfolded on her computer screen, said Scott-Van Zeeland, “I ran around the lab screaming, Eureka!’”

The celebration continues this weekend, she said, following Wednesday’s publication in Science Translational Medicine.

“It’s really exciting. Now we have the tools to look into the genome and to look into the brain. We can actually run this experiment. We’re a whole lot closer than we were” at finding the cause for or fixing autism.

Dr. Stephen Scherer, director of the Centre for Applied Genomics at Toronto’s Hospital for Sick Children, co-wrote the groundbreaking report in June that revealed autism is likely to have hundreds of genetic risk factors.

“From my perspective the data look interesting,” he said of the new study. “But I am not yet convinced the common variant they are testing is actually an autism-risk variant, so while this finding might support that it is, the argument is also somewhat circular.”

Scott-Van Zeeland cautioned that having the risk variant of the gene and the different brain wiring doesn’t mean a child will develop autism in its many forms. Other genetic and environmental factors are still required, she said.

What it does mean is that “very early therapies” such as intensive language training could rewire a young, malleable brain into a “more normal” one, she said.

The risk gene showed up in the brain scans as a frontal lobe over-connected to itself and connected differently to the rest of the brain.

Because of that, the frontal lobe “talks to itself” more than it talks to the rest of the brain. The left side of the brain is associated with language and in children with no risk variants of the gene, the frontal lobe was hooked up to the left side. In risk-variant children, it was hooked to both sides.

“The next step is to find out at what point this difference is detectable,” said Scott-Van Zeeland.

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Since many of children tested were healthy, science still has to learn if the risk variant gene translates into more difficulty acquiring language, even within the “normal” range, for kids who develop normally.

Researchers first examined 32 children, 16 developing normally and 16 with autism. To test their initial findings, they examined another 39 healthy children, 10 with no risk variants of CNTNAP2 and 29 with one or both genes at risk.