Although some clear histopathological differences have been observed between BRCA1-related breast cancer and sporadic cases (more high grade, oestrogen receptor-negative and p53-positive tumours in BRCA1 mutation carriers), this has not been demonstrated for familial cases of breast cancer (Breast Cancer Linkage Consortium, 1997; van de Vijver, 1999). Here, BRCA1 is linked to breast cancer.