Autism is four times more common among males than females, and researchers are getting closer to figuring out why.
“I think the key to actually developing a treatment for autism is to understand the difference between males and females, why female prevalence is much lower,” said Stephen Scherer from the Hospital for Sick Children in Toronto.
“They must have some protective factors in their biology. So we think that this finding may lead us to discovering what those protective factors are.”
For the study, researchers analyzed genetic data from 1,158 Canadians and 456 Europeans with autism spectrum disorder and discovered a family in which males carrying the glitch were affected for four generations, but females were not. The males had high-functioning autism spectrum disorder, with a high IQ and strong verbal skills but poor social communication.
Researchers found that the SHANK 1 gene is involved. When male fetuses are missing one copy of the gene, it affects the developmental process so much that it leads to autism, but in female biology it makes no difference.
“These results will also have immediate relevance for clinical genetic testing in autism spectrum disorder,” the study’s authors concluded.
The gene can be tested for, so doctors can diagnose early on and treat affected males. If 100 people with autism spectrum disorder are given a full battery of genetic tests, Scherer estimated they could account for the genetic cause in 20 percent of those cases. Researchers have pinpointed three SHANK genes that are involved with neuron formation and interaction in the brain.
“We do have a handle on a significant proportion now,” Scherer said.
On its own, SHANK1 would account for 0.1 percent of the affected population, he said. This shows how scientists are slowly but successfully chipping away at figuring out what contributes to autism even though each person is a “genetic snowflake” with a unique form.
The study is published in the American Journal of Human Genetics.
Source: The Hospital for Sick Children