Gene variant may depress IQ of males
THE DALLAS MORNING NEWS
DALLAS Scientists in North Carolina say they have identified a gene that affects IQ, a finding that, if confirmed, would be a significant step toward understanding the genetic basis for intelligence.
The new research could also have ethical implications because the effect of the gene appears to be quite dramatic: The scientists say that males who inherit a particular version of the gene have, on average, an IQ that is 20 points lower than males who don’t.
„I have to admit, the ramifications of it are great,“ said Randy Jirtle, the Duke University biologist who led the new research, noting that current genetic-testing techniques can easily determine which males have that version.
However, he stressed that the IQ results in his research were based on a group average; individual males carrying the gene version had a wide range of IQ scores. While females also can carry the variation, it does not appear to affect their IQ, he said.
Jirtle reported the new findings last month at a scientific conference in Durham, N.C.
As early as the 1920s, research suggested that genetics play a key role in determining a person’s mental capabilities.
But so far, connections between IQ and specific genes have been just correlations, with little supporting evidence. The new research, Jirtle and other experts said, will need to be replicated before it is considered definitive.
Jirtle’s research centers on a gene identified as IGF2R, for type 2 insulinlike growth factor receptor. The gene governs the production of a protein that, among other jobs, affects cell growth. All people carry the gene, but some have a version with a slightly different code, Jirtle said. This variation, he and his colleagues found, correlates with a lower IQ.
The researchers studied about 300 children with an average age of 10. The children, all Caucasian, came from six counties in the Cleveland area. As a group, males but not females who had the variant gene had IQ scores about 20 points lower than males who didn’t.