SNPs genotyped in the ACS subjects included those in the neuronal nicotinic acetylcholine receptor genes with p < 0.05 in the initial univariate analysis of the COGEND study of nicotine dependence (Bierut et al. 2007) and additional haplotype-tagging SNPs chosen using the method of Gabriel et al. (2002). After filtering for genotype quality control, the ACS data used in our analyses contain a total of 61 cholinergic nicotinic receptor subunit SNPs (a subset of the 210 COGEND cholinergic nicotinic receptor subunit SNPs). Detailed descriptions of the ACS sample ascertainment and genotyping quality control are described in Stevens et al. (2008).
