Consistent with previous work (20, 22), the majority of the significant cis-eQTLs clustered around the TSS of target genes in all nine tissues (fig. S9, A and B, and fig. S10). The eQTL signals also tended to show an upstream bias (fig. S10 and tables S6 and S7); an average of ~80% of significant eQTLs fell within ±100 kb around the TSS, and ~60% of all eQTLs were upstream despite testing a similar fraction of SNPs upstream and downstream of the TSS (tables S6 and S7) (23). A slight but distinct overrepresentation of nonsignificant eQTLs around the TSS (relative to other SNPs near the gene; red versus black line in figs. S9A and S11A) supports the existence of additional eGenes, which did not meet significance with current sample sizes.
