TP53 and neoplasm: Patients who were BRCA1+ and were under 50 years old at diagnosis differed significantly in all of these factors from familial non-BRCA1/2 patients (proportion of grade 3 tumours, 84.4% vs 17.3%, respectively, P ≤ 0.0005; of ER-negativity, 83.3% vs 29.3%, P ≤ 0.0005; of PR-negativity, 90.3% vs 31.0%, P ≤ 0.0005; and of p53-positivity, 50.0% vs 25.9%, P = 0.024).