Scientists dispute gene study results

NEW YORK (AP) — It made headlines last year: Scientists said they’d identified a gene that helps determine how anxious or laid-back people are.
Now another group of scientists says they found no sign of that effect.
That doesn’t necessarily mean last year’s study was wrong. It may only mean the gene affects anxiety traits in some groups but not others, says one author of the new study, Richard Ebstein of the Sarah Herzog Memorial Hospital in Jerusalem.
But an author of last year’s study says Ebstein’s project couldn’t have detected the effect anyway.
It’s at least the second time since November that a study proposing a personality gene has been followed by another that found no evidence. Last November it happened to Ebstein.
The new study followed up on a report from scientists in Germany and at the National Institutes of Health.
That report assessed 505 people with two psychological tests. In addition to those results, researchers used the data to predict how the subjects would have scored on a third test, which measures an anxiety-related trait called “harm avoidance.”
Across the three measures, a particular variant of the gene showed a consistent but small effect on a cluster of personality traits that are related to anxiety, they reported.
The gene plays a role in a brain communication system that uses the chemical serotonin.
Ebstein and colleagues report in the May issue of the journal Molecular Psychiatry that they found no effect of the gene variant on the harm avoidance trait, which they measured directly in 120 men and women.
“Now there is some element of doubt (about the original study) but it doesn’t mean they’re wrong,” Ebstein said in a telephone interview. Because of differences in genetic backgrounds and environment, the gene may influence the trait in some groups but not Israelis, he said.
Dean Hamer of the National Cancer Institute, one author of last year’s study, called Ebstein’s result meaningless.
The Israelis studied far too few people to detect the small effect on harm avoidance that last year’s study found, he said. Even with the 505 people in last year’s study, the effect was barely noticeable, Hamer said.
Ebstein said he didn’t check statistically to see if he had enough people to find an effect of the size reported last year. But his results didn’t even give a hint of one, he said, so he concludes it’s not there.
Ebstein himself published a study last year that suggested a gene influenced a trait called novelty-seeking, which includes impulsivity and excitability. Hamer and NIH colleagues got confirming results.
But 10 months later, another group reported finding no trace of that effect in two groups of Finns.