U.S. psychiatric geneticists say they have confirmed an association between genetics and intelligence.

Washington University School of Medicine researchers in St. Louis gathered the most extensive evidence to date showing a gene that activates signaling pathways in the brain influences one kind of intelligence.

They report confirming a link between the gene CHRM2 and performance IQ, which involves a person's ability to organize things logically.

"This is not a gene FOR intelligence," said Danielle Dick, an assistant professor of psychiatry and lead author of the study. "It's a gene that's involved in some kinds of brain processing, and specific alterations in the gene appear to influence IQ. But this single gene isn't going to be the difference between whether a person is a genius or has below-average intelligence."

Dick's team found several variations within the CHRM2 gene could be correlated with slight differences in IQ performance scores that measure such things as visual-motor coordination and abstract problem solving skills.

The study's findings are available online in Behavioral Genetics and will appear in an upcoming print issue of that journal.