The third study, from researchers in Iceland, also looked through the human genome to find genes associated with the number of cigarettes a person smokes daily. Using data from more than 70,000 smokers, it confirmed that genes on chromosome 15 were linked to tobacco use. The researchers also found two genes, CYP2A6 and CYP2B6, that were involved in nicotine metabolism and two others, CHRNB3 and CHRNA6, that play a role in how the body processes nicotine.
Some of these gene regions are also associated with a predisposition to lung cancer, the researchers noted.
"Key variants in each region associate with nicotine dependence and lung cancer, bringing up the question of whether the risk for lung cancer is through the effect on smoking behavior or whether it involves increased vulnerability to the harmful effects of smoking as well," the authors wrote.
Dr. Norman H. Edelman, scientific consultant to the American Lung Association, said that the information reported by the study "adds to the current limited data indicating that predilection to smoking has some, perhaps significant, genetic component."
However, Edelman said he thinks that any direct benefit from the findings is a ways off.
"I don't think it will directly alter our approach to smoking cessation and prevention in the short term, but down the line it may help change attitudes toward smokers," he said.
Too many people think of smokers as having self-imposed diseases, Edelman said. "Now we can see some had to fight a genetic predilection while being addicted by an aggressive tobacco industry while they were children, as almost all smokers start as teens or preteens."
Robert West, a professor of health psychology and director of tobacco studies at the Cancer Research UK Health Behaviour Unit at the University College London, added that "there is clear evi
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