Genetic variability at 5p13 also contributes to other diseases with inflammatory components, including Crohn's disease,26, 27, 28, 29, 30, 31 ulcerative colitis,32, 33, 34 ankylosing spondylitis35 and multiple sclerosis.36, 37, 38 Furthermore, cis‐regulatory effects involving the expression of PTGER4 in some of these traits have been described previously in lymphoblastoid cell lines.39 However, all SNPs and eQTLs implicated in these studies are only in weak LD (r2 < 0.3) to the GC variants and PTGER4‐eQTLs identified in the present study (see Table S6). This evidence concerns the gene PTGER4 and ulcerative colitis.