BRCA1 and cancer: Polygenic risk scores (PRS) based on the combined effects of disease-associated SNPs, can lead to significant levels of breast and ovarian cancer risk stratification in the general population.8,9 It has also been demonstrated that PRS can result in large absolute risk differences of developing these cancers for BRCA1/2 carriers.10 The largest study to date was a retrospective cohort study of 23,463 carriers using a PRS based on up to 88 breast cancer susceptibility SNPs and a PRS based on up to 17 ovarian cancer susceptibility SNPs.10