The observation that the only gene of the three tested found by multigenetic logistic regression analysis to be independently associated with tumour differentiation was BRCA1 (Table 2) is consistent with the tumour spectrum observed in familial cancer syndromes caused by mutation of ATM, BRCA1 or TP53, with only BRCA1 being specifically associated with familial breast cancer (Holt et al, 1996). Here, TP53 is linked to hereditary breast carcinoma.