Rare coding variants and breast cancer risk: Evaluation of susceptibility loci identified in genome-wide association studies
A partir de données d'études d'association sur le génome entier et de la cohorte "Shanghai Breast Cancer Study" portant sur 3 472 cas et 3 595 témoins, cette étude analyse l'association entre des polymorphismes à simple nucléotide rares de 67 loci précédemment identifiés et le risque de cancer du sein
Background: To date, common genetic variants in ~70 loci have been identified for breast cancer via genome-wide association studies (GWAS). It is unknown whether rare variants in these loci are also associated with breast cancer risk. Methods: We investigated rare missense/nonsense variants with minor allele frequency (MAF) ≤ 5% located in flanking 500 kb of each of the index SNPs in 67 GWAS loci. The study included 3,472 cases and 3,595 controls from the Shanghai Breast Cancer Study. Both single marker and gene-based analyses were conducted to investigate the associations. Results: Single marker analyses identified 38 missense variants being association with breast cancer risk at P < 0.05 after adjusting for the index SNP. SNP rs146217902 in the EDEM1 gene and rs200340088 in the EFEMP2 gene were only observed in 8 cases (P=0.004 for both). SNP rs200995432 in the EFEMP2 gene was associated with increased risk with an odds ratio (OR) of 6.2 (95% CI:1.4-27.6, P=6.2×10-3). SNP rs80358978 in the BRCA2 gene was associated with 16.5-fold elevated risk (95% CI:2.2-124.5, P=2.2×10-4). Gene-based analyses suggested eight genes associated with breast cancer risk at P<0.05, including the EFEMP2 gene (P=0.002) and the FBXO18 gene (P=0.008). Conclusion: Our results identified association of several rare coding variants neighboring common GWAS loci with breast cancer risk. Further investigation of these rare variants and genes would help to understand the biological mechanisms underlying the associations. Impact: Independent studies with larger sample size are warranted to clarify the relationship between these rare variants and breast cancer risk.