Rare coding variants and breast cancer risk: evaluation of susceptibility Loci identified in genome-wide association studies.
BACKGROUND
To date, common genetic variants in approximately 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 single-nucleotide polymorphism (SNP) in 67 GWAS loci. Included in the study were 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 associated 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 OR of 6.2 [95% confidence interval (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).


CONCLUSIONS
Our results identified associations 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 biologic mechanisms underlying the associations.


CONCLUSIONS
Independent studies with larger sample size are warranted to clarify the relationship between these rare variants and breast cancer risk.
Authors' Affiliations: Division of Epidemiology, Department of Medicine, Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center; Department of Biostatistics; Department of Molecular Physiology and Biophysics, Center for Human Genetics Research, Vanderbilt University School of Medicine, Nashville, Tennessee; Shanghai Center for Disease Control and Prevention; and Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China.
Yanfeng
Y
Zhang
Jirong
J
Long
Wei
W
Lu
Xiao-Ou
XO
Shu
Qiuyin
Q
Cai
Ying
Y
Zheng
Chun
C
Li
Bingshan
B
Li
Yu-Tang
YT
Gao
Wei
W
Zheng
D001943:Breast Neoplasms / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D056426:Genetic Loci; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D008875:Middle Aged; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors