Impact of fetal expression quantitative trait loci on transcriptome-wide association study of childhood leukemia

Transcriptome-wide association studies increase the yield of loci associated with disease phenotypes by focusing on expression quantitative trait loci (eQTL). The major source of eQTL data for is the Gene and Tissue Expression (GTEx) project, which is comprised entirely of adults, mainly those >50 years of age at death. Since gene expression levels differ by developmental stage, it is not clear whether eQTLs derived from adult data sources are best suited for use in young-onset diseases such as pediatric cancers. To fill in this knowledge gap, we performed a large-scale eQTL mapping analysis in the GenCord study with newborn samples and compared it with GTEx. Under matched conditions, we found around 80% of the eQTLs in one study can be replicated in the other. However, among all eQTLs identified in GenCord (GTEx), 584 (1045) showed statistically significant differences in effect sizes in GTEx (GenCord). We further investigated how using fetal eQTL data can facilitate the genetic association study of acute lymphoblastic leukemia. GenCord and GTEx identified the same genetic loci with statistical significance; however, the overall association pattern was only weakly correlated. Our paper demonstrates age-differential eQTLs and shows their potential influence on childhood leukemia research.