Those in the second group likely bear a gene type that not  only increases their addiction risk, but has been implicated in  the development of lung cancer, researchers said on Friday. “If you have this variant, you are going to like your  earliest experiences with smoking,” said Ovide Pomerleau of the  University of Michigan Medical School, whose research appears  in the journal Addiction. Pomerleau said the finding suggests that for some, smoking  even one cigarette is a bad idea. “It’s a trap,” he said in a  telephone interview. “What they don’t realize is if they have this kind of  genetic make-up, they are on their way to dependency,” he said,  and that raises their risk for lung cancer. The research is part of a growing understanding of genetic  factors involved in nicotine addiction and lung cancer. Teams of scientists reported earlier this year that smokers  who had certain changes in three nicotine receptor genes —  which control entry of nicotine into brain cells — were more  likely to develop lung cancer than other smokers. This week, Canadian researchers said that, by manipulating  receptors for the chemical dopamine, they were able to control  which rats in a study enjoyed their first exposure to nicotine  and which were repelled by it. Pomerleau said the field may soon lead to new treatments  for nicotine addiction and tests to assess addiction risks. Smoking causes nine out of 10 cases of lung cancer, the  leading cause of cancer death in men worldwide and the  second-leading cause of cancer death among women. Pomerleau and colleagues studied data from 435 people. Some  had tried a cigarette but never developed a habit; others  smoked at least five cigarettes a day for the past five years. Regular smokers in the study were far more likely than  those who had never smoked to have a change in the CHRNA5  nicotine receptor gene. Smokers were eight times more likely to  report liking cigarettes from the start. Pomerleau said work has begun to develop a genetic screen  for the CHRNA5 variant. Two other researchers on the team,  Laura Bierut and John Rice at Washington University, hold a  patent on the gene variant, which has been licensed by  privately held Perlegen Sciences Inc.    Pfizer Inc, maker of the smoking cessation drug Chantix  owns a $50 million stake in Perlegen. Pomerleau, who has served on Pfizer’s scientific advisory  board, said he favors development of diagnostic tests, as long  as people understand it is not the only risk factor for  nicotine addiction. “What we don’t know is far greater than what we do know,”  he said.
Gene raises risk of lifetime smoking habit: study.