Results from 27 datasets, containing a total of 32,587 smokers with measures of cigarettes per day, contributed to the meta-analyses. Of these datasets, 9 consisted of European ancestry subjects (N=14,786), 7 consisted of Asians (N=6,889), and 11 consisted of African Americans (N=10,912). Twenty datasets were samples of unrelated individuals. The remaining seven datasets were family-based studies, for which the primary analyses involved an extraction of unrelated individuals. To be included in the analyses, each subject was required to have reported smoking cigarettes in his/her lifetime. Genotyping varied among studies from extensive coverage based on genome wide association genotyping to only a limited number of candidate SNPs genotyped in this 15q25 region. Text S1 provides additional details for each dataset, including recruitment, primary phenotypes, definitions for smokers and cigarettes per day, DNA source, genotyping platforms, and genotyping quality control. Table S1 shows the sample size and demographics for each participating dataset. Four of nine datasets of European ancestry were included in the previous report [Saccone, et al. 2010] (see Table S1 for the overlap, which involves only European-ancestry samples). The informed consent from participants and approval from the appropriate institutional review boards were obtained.
