NEW YORK (AP) _ Scientists have identified a gene that might slightly raise a person's risk of getting addicted to heroin.

The work is preliminary, but experts said it could be a step toward giving doctors a way to identify people vulnerable to heroin addiction. Such people could then be steered into prevention programs.

The gene is the same one that made headlines last year when researchers linked it to a personality trait called novelty-seeking, which includes impulsiveness, excitability and extravagance. Not all studies have found that link.

Drug abusers tend to score high on tests for this trait, which was one reason researchers decided to see if the gene influences the risk of heroin addiction.

In fact, the novelty-seeking trait might lead to the addiction risk, said Richard Ebstein of the Sarah Herzog Memorial Hospital in Jerusalem, the main author of the new study.

The gene also plays a role in a brain communication system that's implicated in addiction. Many brain cells communicate with each other by squirting a substance called dopamine. These brain-cell circuits are crucial to producing the psychological reward people feel with drugs.

Brain cells receive the dopamine signal on surface structures called receptors. The gene in the new study tells cells how to make one type of dopamine receptor.

Ebstein and colleagues focused on one variant of this gene. They found that 29 percent of a group of Israeli male heroin addicts had this variant, compared with only 12 percent of a group of nonaddicted Israeli men.

A statistical analysis found that people with the variant are about 2 1/2 times as likely to become addicted to heroin, the researchers reported in the May issue of the journal Molecular Psychiatry.

The study involved 141 addicts and 110 men with no history of substance abuse.

Ebstein said the gene variant is common in the general population, found in perhaps 30 percent of people in Europe and North America, so it's obviously not enough to make somebody a heroin addict. But ``it gives you a slightly increased risk.''

Scientists need to look more genes that affect a person's vulnerability to heroin addiction, he said.

Alan Leshner, director of the National Institute on Drug Abuse, called the work encouraging but stressed that genes aren't the only reason for addiction.