`FIRST MISSING LINK' FOUND FOR GENES AND PERSONALITY

Impulsive? Fickle? Quick-tempered? It could be in your genes.

Scientists say they've taken a step toward unraveling the genetics of personality by discovering a gene that could influence how excitable and impulsive you are.The discovery - made in two separate studies - provides the first confirmed association between a particular gene and a normal personality trait.

Previous studies have shown more generally that genes influence personality, as do a person's life experiences.

As scientists discover more individual genes that affect particular traits, it might open the door to identifying people at risk for such problems as drug abuse and counseling them on how to lower their risk, said researcher Richard Eb-stein.

It might also add a twist to the issue of who's entitled to know about a person's genetic makeup.

An insurance company might want to know that "genetically you're a thrill-seeker and enjoy jumping out of airplanes in a skydiving club and taking risks in general," said Ebstein, director of research at the Sarah Herzog Memorial Hospital in Jerusalem.

Ebstein is the lead author of one study of the gene in the January issue of the journal Nature Genetics. The second study reproduced Eb-stein's results in a different population.

"This is major news," said psychologist Brian Gladue, who studies the biology of behavior at the Institute for Policy Research at the University of Cincinnati.

"This is going to open up a whole new field of molecular personality research," he said.

The discovery provides "the first missing link" between genes and personality by implicating a particular communication system in the brain, Gladue said.

In that communication system, brain cells signal each other with a chemical messenger called dopamine. Dopamine is secreted by signaling cells, and delivers its message by binding to receptors on the surface of receiving cells.

The gene identified in the study tells cells how to make one kind of dopamine receptor.

The studies found that, on average, people with a particular version of the gene score about 10 percent higher on personality tests for a trait scientists call "novelty seeking."