Abstract | Genome-wide association studies (GWAS) have identified more than 170 breast cancer susceptibility loci. We hypothesized that some risk-associated variants might act in non-breast tissues, specifically adipose tissue and immune cells from blood and spleen. Using expression quantitative trait loci (eQTL) reported in these tissues, we identified 26 previously unreported, likely target genes of overall breast cancer risk variants, and 17 for estrogen receptor (ER)-negative breast cancer, several with a known immune function. Directional effect of gene expression on disease risk was determined based on single and multiple eQTL. In addition, using a gene-based test of association that considers eQTL from multiple tissues, we identified seven (and four) regions with variants associated with overall (and ER-negative) breast cancer risk, which were not reported in previous GWAS. Further investigation of the function of the implicated genes in breast and immune cells may provide insights into the etiology of breast cancer. |
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