Five samples were used to conduct our GWAS meta-analysis of nicotine dependence: deCODE Genetics,4 Environment and Genetics in Lung Cancer Etiology Study (EAGLE),14, 15 Chronic Obstructive Pulmonary Disease Gene (COPDGene) Study,16 Collaborative Genetic Study of Nicotine Dependence (COGEND)3 and Study of Addiction: Genetics and Environment (SAGE*).9 These study participants, all of European-ancestry, had genome-wide SNP genotypes and FTND10, 11 scores to define nicotine dependence among participants who reported smoking more than 100 cigarettes in their lifetime. Quality control (QC) was conducted on genotyped participants and SNPs in each sample using PLINK17 unless otherwise stated.
