LD is measured as the ξ coefficient, a standardized measure of overall nonrandomness of alleles at the sites in the haplotypes⁷⁰. The bars are the mean values of ξ across the same 21 independent haplotype systems in all populations. The standard errors of the means are given as the error bars and the median values are plotted as dots connected by the line. Bars are color-coded by geographic region of origin of the populations, from left to right as sub-Saharan Africa, African Americans, Southwest Asia, Europe, East Asia, Pacific, Siberia, North America and South America. Population and sample descriptions are in ALFRED⁶⁹. Different samples of populations with the same name are distinguished by initials: SF, San Francisco; TW, Taiwan; AZ, Arizona; MX, Mexico; R, Rondonian. The haplotyped loci were chosen with no prior knowledge of LD values at the locus. The number of sites per haplotyped locus varied from 2 to 7 for a total of 83 SNPs. The graph is based on published data on CD4, DM1, DRD2, DRD4, PAH and COMT plus unpublished data. These results show less LD in African populations than elsewhere and greater LD in the Native American populations than in other regions, as well as variation in LD within geographic regions.