Genetics Of Autism
More evidence of a genetic basis for autism;
Using DNA samples from 120 families likely to possess a genetic risk factor on chromosome 17, the team found 19 different SERT mutations ( or variants ) in families with multiple affected males, consistent with the well-known sex-bias seen in autism incidence.
Four of these variants were in ‘coding’ regions, or parts of the gene that get translated into protein. The other 15 variants were in ‘noncoding’ regions, which are edited out of the final protein product but may have important regulatory roles in the expression of the gene. “These coding mutations tracked with an increased severity of rigid- compulsive behaviors,” Sutcliffe explained. These types of behaviors are a common characteristic of autism and related disorders like obsessive-compulsive disorders.
The findings underscore the relationship between autism and disorders like OCD and may explain why SSRIs are effective in treating these conditions, he said.
Based on these findings, Blakely and Sutcliffe predict that there will one day be a way to test autistic children for these gene variants, similar to the testing done for cystic fibrosis, a disease linked to a single gene but triggered by many different mutations.
“Autism has such a high genetic risk, but these new findings suggest that there may be many variants of individual genes at work,” Blakely said.
With such genetic testing, said Sutcliffe, “you might be able to predict which kids would respond positively to particular SSRI medications.”
“We now have concrete evidence in our families that the SERT gene is a risk factor in autism,” Blakely said. “Perhaps more importantly, we also have new pathways that could have some therapeutic end points, and that, to us, is really good news.”