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. Author manuscript; available in PMC: 2014 Dec 1.
Published in final edited form as: Nat Genet. 2014 May 11;46(6):543–550. doi: 10.1038/ng.2982

Figure 4. Epistatic effects and Mendelian randomization analyses on eQTL loci.

Figure 4

(A) Interaction between NAT8 and PYROXD2 variants. Levels of the metabolite X-12093 are plotted as a function of genotypes at the two variants rs10469966 (NAT8) and rs4488133 (PYROXD2), showing a significant SNP*SNP interaction on metabolite levels. See also Supplementary Figure 4. (B) Regional plots illustrating overlap of association of SNPs with metabolites (red) and gene expression levels measured in fat (black), skin (blue) and LCLs (green) at locus 11. Associations p-values (–log10 scale) are plotted for a 1 Mb window surrounding the lead SNP rs6693388, and for associations of the SNP with linoleate (18:2n6)/ 5,8-tetradecadienoate (red), and with THEM4 expression in fat (black), skin (blue) and LCL (green) respectively. (C) Example of relationships tested by Mendelian randomization analysis at the same locus, where expression of gene THEM4 is shown to mediate the association between rs6693388 and the ratio linoleate (18:2n6) to 5,8-tetradecadienoate. All analyses were done in a subset of 484 unrelated TwinsUK participants with gene expression measured at the same time of visit of metabolomic measurements. The full results are in Supplementary Table 11.