Immunohistochemical detection of a germline BRCA1 mutation in a breast andovarian cancer family

Tumours from four individuals in a breast and ovarian cancer family with a known deleterious germline BRCA1 mutation, were analyzed using BRCA1 antibo dies. In addition, we examined tumours from 96 female patients with early-o nset breast cancer, who were not selected because of any family history. Pa raffin-embedded tumour sections were examined by standard immunohistochemic al analysis. Three familial tumours from BRCA1 carriers displayed focal neg ativity. This observation was not seen in a non-mutation carrier from the s ame family. It was found that 9/96 (9%) early-onset breast rumours had tota l BRCA1 negativity. In addition, 2/2 (100%) medullary breast carcinomas dis played negativity for both antibodies. Our results indicate that BRCA1 anti bodies can discriminate between familial tumours with and without a deleter ious mutation from one family. Further mutation studies in early-onset brea st cancer group will be necessary to evaluate the use of immunohistochemist ry as a rapid, initial screening technique to identify BRCA1 mutations. (C) 2000 Harcourt Publishers Ltd.