Many other factors, such as depth of inhalation, number of puffs per cigarette, and age of starting smoking are also likely to affect the toxicant exposure and effect. Second, we also tested directly for an association between the amount of smoking, measured as pack-years, within cases and controls with the SNP rs8034191. There was no significant association between the SNPs and pack-years of smoking in the Bergen and NETT/NAS populations. This is consistent with the observed allele frequency among the Norwegian pediatric general population sample (minor allele frequency = 0.326, n = 551) which is between that observed for cases and controls and not significantly different from either.
