Worldwide haplotype distribution. The frequencies of 7 globally distributed haplotypes for 6 SNPs in the VKORC1 gene are represented by pie charts over the country of origin of population samples from which they were derived. The SNPs are listed in the order in which they occur along the VKORC1 gene: −1639G>A, 497T>G, 1173C>T, 1542G>C, 2255C>T, 3730G>A. All haplotypes occurring at frequencies of less than 2.5% in all population samples tested are grouped together in the “Other” category. For the United States, the population samples are broken down into white (W), black (B), and Mexican American (MA) subgroups and by the study under which they were collected: International Warfarin Pharmacogenetics Consortium or National Health and Nutrition Examination Survey III. Detailed data underlying this figure can be found in supplemental Table 5.