The penetrance of breast cancer in BRCA1 mutation carriers appears to vary considerably. The cumulative risk of breast cancer by age 70 for a BRCA1 mutation carrier has been estimated at anywhere from 44% to 80%. Variable penetrance and age of onset of breast cancer among related BRCA1 carriers sharing the same deleterious mutations has been observed and differences in breast cancer risk between population-based families and high-risk clinic-based families with the same mutations have also been detected. These and other observations strongly suggest the existence of common genetic variants that modify the risk of cancer in BRCA1 mutation carriers. Our goal in this study is to identify genetic modifiers of breast cancer risk in BRCA1 carriers through a genome wide association study with the intent of substantially improving understanding of the etiology of these tumors as well as pathologically related triple negative breast tumors. These modifiers should also prove useful for improved risk assessment of BRCA1 mutation carriers. We propose to accomplish this through a multi-stage approach using DNA samples from BRCA1 mutation carriers that have been collected through an international consortium. In stage 1 we aim to genotype 1,500 BRCA1 carriers with young onset breast cancer and 1,500 older unaffected BRCA1 carriers on 550,000 common variants and identify variants associated with risk of breast cancer. In stage 2 we will evaluate the 13,180 variants most significantly associated with breast cancer risk in 2,000 affected and 2,000 unaffected carriers and combine the data with stage 1 to increase statistical power. In stage 3 the 384 most significant variants will be further evaluated in 2,000 affected and 2,000 unaffected BRCA1 carriers and the data will be combined with data from stages 1 and 2. In parallel, because most BRCA1 mutant tumors are triple negative tumors, we will evaluate associations between the variants in stage 3 and risk of triple negative breast cancer using 1,500 basal breast cancer patients and 1,500 matching controls provided by the Breast Cancer Association Consortium. In stage 4 fine mapping of the genomic regions containing the most significantly associated variants will be conducted to identify the variants that likely account for the modification of breast cancer risk in BRCA1 carriers. PROJECT NARRATIVE The identification of genetic modifiers of breast cancer risk in BRCA1 carriers will be useful for understanding the etiology of BRCA1 mutant breast cancer and triple negative breast cancer and for developing novel therapeutic targets. The modifiers may also lead to development of improved risk assessment models that better discriminate between high and lower risk BRCA1 mutation carriers.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Epidemiology of Cancer Study Section (EPIC)
Program Officer
Seminara, Daniela
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Mayo Clinic, Rochester
United States
Zip Code
Shi, Jiajun; Zhang, Yanfeng; Zheng, Wei et al. (2016) Fine-scale mapping of 8q24 locus identifies multiple independent risk variants for breast cancer. Int J Cancer 139:1303-17
Lei, Jieping; Rudolph, Anja; Moysich, Kirsten B et al. (2016) Genetic variation in the immunosuppression pathway genes and breast cancer susceptibility: a pooled analysis of 42,510 cases and 40,577 controls from the Breast Cancer Association Consortium. Hum Genet 135:137-54
Gusev, Alexander; Shi, Huwenbo; Kichaev, Gleb et al. (2016) Atlas of prostate cancer heritability in European and African-American men pinpoints tissue-specific regulation. Nat Commun 7:10979
Muranen, Taru A; Greco, Dario; Blomqvist, Carl et al. (2016) Genetic modifiers of CHEK2*1100delC-associated breast cancer risk. Genet Med :
Dite, Gillian S; MacInnis, Robert J; Bickerstaffe, Adrian et al. (2016) Breast Cancer Risk Prediction Using Clinical Models and 77 Independent Risk-Associated SNPs for Women Aged Under 50 Years: Australian Breast Cancer Family Registry. Cancer Epidemiol Biomarkers Prev 25:359-65
Easton, Douglas F; Lesueur, Fabienne; Decker, Brennan et al. (2016) No evidence that protein truncating variants in BRIP1 are associated with breast cancer risk: implications for gene panel testing. J Med Genet 53:298-309
Painter, Jodie N; O'Mara, Tracy A; Marquart, Louise et al. (2016) Genetic Risk Score Mendelian Randomization Shows that Obesity Measured as Body Mass Index, but not Waist:Hip Ratio, Is Causal for Endometrial Cancer. Cancer Epidemiol Biomarkers Prev 25:1503-1510
Wen, Wanqing; Shu, Xiao-Ou; Guo, Xingyi et al. (2016) Prediction of breast cancer risk based on common genetic variants in women of East Asian ancestry. Breast Cancer Res 18:124
Darabi, Hatef; Beesley, Jonathan; Droit, Arnaud et al. (2016) Fine scale mapping of the 17q22 breast cancer locus using dense SNPs, genotyped within the Collaborative Oncological Gene-Environment Study (COGs). Sci Rep 6:32512
Bonilla, Carolina; Lewis, Sarah J; Martin, Richard M et al. (2016) Pubertal development and prostate cancer risk: Mendelian randomization study in a population-based cohort. BMC Med 14:66

Showing the most recent 10 out of 150 publications