Smoking may be especially addictive for young people with certain gene mutations.

So say Jennifer O’Loughlin of McGill University (search) and colleagues, after studying about 280 Canadian seventh graders who had started smoking.

A variety of factors determine whether someone initiates smoking and develops a dependence on nicotine. In adults, some studies have shown that nicotine addiction is linked to a person's genetics and the mechanisms in the liver that break down nicotine.

Abnormalities in the genes that break down nicotine might protect a new smoker against nicotine addiction by exposing him or her to nicotine toxicity symptoms, such as dizziness and nausea.

The study looked at the association between the genes that metabolize and break down nicotine and whether inactive genes would protect young teen smokers from tobacco addiction.

In roughly 2.5 years, more than 29 percent of the students became hooked on cigarettes.

The risk was especially high for those with an inactive CYP2A6 gene, which oversees clearing nicotine out of the body.

Mutations can leave that gene partially or totally inactive. That could make people more vulnerable to nicotine.

The longer nicotine lingers, the more chance it has to lure the body into addiction.

The students with the gene mutations smoked fewer cigarettes per week than those with the normal gene.

Those with the totally inactive gene smoked about 13 cigarettes weekly, compared with 29 for those with normal genes.

That may be because the nicotine buzz lasted longer in the gene mutation group, reducing their cigarette cravings.

The mutation deserves further study, say the researchers in the December issue of the journal Tobacco Control.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: O’Loughlin, J. Tobacco Control, December 2004; vol 13: pp 422-428. News release, BMJ Specialist Journals.