Several studies have shown that stratification of breast tumours by ER and PR status might be useful in partitioning breast cancer families into more homogeneous subsets [35], but we have found that these traditional immunohistochemical features are not as important as morphological features for predicting BRCA1 mutation carriers [12] or, as in this study, predicting breast cancer risks for relatives. This evidence concerns the gene ESR1 and breast carcinoma.