Germline Allelic Expression of Genes at 17q22 Locus Associates with Risk of Breast Cancer

Translation of GWAS findings into preventive approaches is challenged by identifying the causal risk variants and understanding their biological mechanisms. We present a novel approach using AE ratios to perform quantitative case-control analysis to identify risk associations, causal regulatory variants, and target genes. Using the breast cancer risk locus 17q22 to validate this approach, we found a significant shift in the AE patterns of STXBP4 (rs2628315) and COX11 (rs17817901) in the normal breast tissue of cases and healthy controls. Preferential expression of the G-rs2628315 and A-rs17817901 alleles, more often observed in cases, was associated with an increased risk for breast cancer. Analysis of blood samples from cases and controls found a similar association. Furthermore, we identified two putative cis-regulatory variants - rs17817901 and rs8066588 - that affect a miRNA and a transcription factor binding site, respectively. Our work reveals the power of integrating AE data in cancer risk studies and presents a novel approach to identifying risk - case-control association analysis using AE ratios.