The presence of a CYP2A6del allele, a specific form of the gene involved in processing nicotine in the body, may inhibit smokers from quitting, but it also seems to protect against the development of pulmonary emphysema, they conclude.
DNA was taken from 203 current or ex-smokers with suspected COPD and from 123 non-smoking healthy volunteers with few respiratory symptoms. All subjects were interviewed. Among the current or ex-smokers, the number of cigarettes consumed per day, the duration of smoking, and the time elapsed since quitting were recorded. CYP2A6 genotypes were determined in both groups.
The percentage of subjects with a CYP2A6del allele was lower in heavy smokers than in light smokers or non-smokers. It was also lower in ex-smokers than in current smokers.
The CYP2A6del allele appears to restrict the amount of lifelong cigarette consumption in heavy smokers but not in light smokers, say the authors. The CYP2A6del allele also appears to inhibit smokers from quitting smoking and acts as an intrinsic factor against the development of pulmonary emphysema, they write.
"These findings suggest that determination of the genotype will be useful in efficiently withdrawing patients from nicotine dependence in smoking cessation protocols with nicotine containing materials, and will give a new insight into the pathogenesis of smoking induced pulmonary emphysema," they conclude.
Thorax