Figure 2.
Examples of biomarker pQTL (protein quantitative trait locus) SNPs. Plasma levels of (A) IL6R and (B) E-selectin are strongly influenced by pQTL SNPs (P = 10−193 and P = 4 × 10−104, respectively). Biomarkers were transformed to standard normal distribution, and statistical testing was performed using PLINK version 1.9 as described elsewhere (30). The pQTL SNP for IL6R (IL-6 receptor) is on chromosome 4, which is local (cis) to IL6R, the gene coding for its protein. The pQTL SNP for E-selectin protein is on chromosome 9, which is distant (trans) from SELE (chromosome 1), the gene coding for its protein. This pQTL SNP is in the ABO locus, which encodes α-1-3-N-acetylgalactosaminyltransferase. SPIROMICS = Subpopulations and Intermediate Outcomes in COPD Study.