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Genes May Play Role in Quitting Smoking

TUESDAY June 3, 2008 -- Your ability to kick the smoking habit may have a lot to do with your genetic make-up, a new study finds.

Researchers have found gene patterns that influence a smoker's response to specific smoking-cessation treatments. The researchers identified several genetic variations that appear to indicate the likelihood of success or failure with nicotine replacement therapy and the smoking-cessation drug bupropion (Zyban).

"There is a significant chunk of evidence that the ability to quit smoking has inheritable components," said lead researcher Dr. George R. Uhl, chief of the molecular neurobiology research branch at the U.S. National Institute on Drug Abuse.

"There is no single gene that has variants related to smoking," Uhl said. "There is no gene that even has a large effect. But nevertheless, we have identified a number of different genes that are all contributors to the individual differences in the ability to quit smoking."

The findings were published in the June issue of the Archives of General Psychiatry.

For the study, Uhl's team analyzed the DNA of 550 smokers who were part of smoking-cessation studies. These people had been randomly assigned to receive either nicotine replacement therapy; the antidepressant Zyban, which has been found to help people quit smoking; or a placebo.

The researchers found 41 gene variants linked to smokers who successfully quit using nicotine replacement therapy, and 26 genes that were specific to successful quitting with Zyban.

Uhl said these genetic variants alone aren't enough to predict successful treatment to quit smoking. And, the specific role these genes play still isn't clear, he said.

But, the findings do explain why different people respond to different smoking-cessation treatments, Uhl said.

"We are now trying to use this information, in new studies of people who are trying to quit, to see if we can increase the power of the approaches to smoking cessation," Uhl said. "We want to target smokers with what would be the best way to help them quit."

In the future, knowing which smokers are more likely to respond to specific treatments would help tailor treatment to individual needs, Uhl said.

The study was supported by the U.S. National Institutes of Health, the tobacco company Philip Morris USA Inc., and the drug maker GlaxoSmithKline.

Dr. Norman H. Edelman, scientific consultant to the American Lung Association, said he thinks that using genetic information to help people quit smoking is still far in the future.

"There are a lot of powerful tools now that let people go on fishing expeditions for genetic linkages, and you're always going to find something," he said. "The fact that they found the few genes that correlate with whether you're successful in smoking cessation is not surprising. Your ability to quit is going to depend at least somewhat on your genetic background."

There may be value in being able to determine who will respond best to individual treatments, Edelman said.

"I don't think this is going to be used clinically anytime soon, but it's of some interest that they could make a distinction about who responds to which treatments," he said.

More information

For more on how to stop smoking, visit the American Cancer Society.

Posted: June 2008


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