Genome-wide metabolite quantitative trait loci analysis (mQTL) in red blood cells from volunteer blood donors

The Red Blood Cell (RBC)-Omics study, part of the larger NHLBI-funded Recipient Epidemiology and Donor Evaluation Study (REDS-III), aims to understand the genetic contribution to blood donor RBC characteristics. Previous work identified donor demographic, behavioral, genetic and metabolic underpinnings to blood donation, storage, and - to a lesser extent - transfusion outcomes, but none have yet linked the genetic and metabolic bodies of work. We performed a Genome-Wide Association (GWA) analysis using RBC-Omics study participants with generated untargeted metabolomics data to identify metabolite quantitative trait loci (mQTL) in RBCs. We performed GWA analyses of 382 metabolites in 243 individuals imputed using the 1000 Genomes Project phase 3 all-ancestry reference panel. Analyses were conducted using ProbABEL and adjusted for sex, age, donation center, number of whole blood donations in the past two years, and first ten principal components of ancestry. Our results identified 423 independent genetic loci associated with 132 metabolites (p < 5x10-8). Potentially novel locus-metabolite associations were identified for FLVCR1 and choline, and for LPCAT3 and the lysophosphatidylserine 16.0, 18.0, 18.1, and 18.2; these associations are supported by published rare disease and mouse studies. We also confirmed previous metabolite GWA results for associations including N(6)-Methyl-L-lysine and PYROXD2, and various carnitines and SLC22A16. Association between pyruvate levels and G6PD polymorphisms was validated in an independent cohort and novel murine models of G6PD deficiency (African and Mediterranean variants). We demonstrate that it is possible to perform metabolomics-scale GWA analyses with a modest, trans-ancestry sample size. Key pointsO_LIMetabolite heterogeneity in fresh (<14 day old) RBCs donated by volunteer donors is linked to genetic polymorphisms; C_LIO_LIWe report 2,831 high-confidence SNP-metabolite linkages (p < 5.0 x 10-8). Pyruvate levels in fresh RBCs are associated with glucose-6-phosphate dehydrogenase (G6PD) status C_LI