To date, all published GWAS for smoking behaviors have been conducted in populations of European descent.11 Conducting GWAS in non-European populations, such as African ancestry populations is important because of their greater genetic diversity and population differences in disease allele frequency, linkage disequilibrium patterns and phenotype prevalence.12 For smoking behaviors, the need for GWAS in African American populations is particularly clear; African Americans, on average, initiate smoking later, smoke fewer cigarettes per day, yet are less likely to successfully quit smoking. Further, they have a higher risk of smoking-related lung cancer than many other populations.13 Ethnic differences in the clearance of nicotine, cotinine and other metabolites have been shown to contribute to the observed differences in cigarette consumption across populations, mediated in part by genetic variants in the cytochrome p450 2A6 gene.14, 15, 16
