by smoking history, family history of lung cancer in a first-degree relative, and age. A dominant model was also tested for each SNP, with carriers of one or two copies of the minor allele compared with carriers of two major alleles, and results were very similar to those under the log-additive model so these results are not presented. For each SNP, a model including race and a race × genotype interaction term was also created to evaluate the significance of the difference between SNP associations by race. The association between mean cigarettes smoked per day and genotype was evaluated using one-way analysis of variance within racial group. Linkage disequilibrium (LD) between SNPs was determined using r2 values within each racial group. All statistics were derived using SAS version 9.1 (SAS Institute, Cary, NC), using the genetics module for analyses using SNPs.
