The distribution of cis- associations relative to the transcription start site (TSS) shows that the majority of association signals are approximately symmetrically centered on the TSS (Figure 3), with the majority within 100 Kb of the TSS, as has been previously observed [13], [14], [15], [19], [29]. Significant associations extend out to 1 Mb (the limit tested in this analysis), with the strongest statistical signals located directly at the TSS. Note the smallest population sample, MEX, provided the weakest statistical signals as expected. We observe a pattern to this distribution when we partition associations into categories based on the number of populations in which the gene is found to have a significant cis- association. We observe that for those genes found to have a significant cis-eQTL in only one population, the distribution of most-significantly associated SNPs are uniformly distributed throughout the 2 Mb window (Figure 4 and Figure S11). For genes with significant cis-eQTL associations in all eight populations, the distribution is centered on the TSS, with few associations extending beyond +/−200 Kb from the TSS. As population sharing increases
