BRCA1 and breast cancer: We employed SNP sets for PRS computation as developed and evaluated by Kuchenbaecker et al. [22], which to our knowledge are the only published PRS SNP sets to date specifically adapted for BC risk stratification in women with a BRCA1/2 PV, namely an overall BC PRS comprising 88 loci, a PRS specific for ER+ BC comprising 87 SNPs and a PRS specific for ER- BC comprising 53 SNPs.