[Analysis of mutations in the BRCA1 gene in patients with cancer of the breast and/or the ovary in Portugal].

Germline mutations in the BRCA1 gene confer an increased susceptibility to breast and ovarian cancer. Approximately 460 distinct mutations were founded scattered throughout the whole gene. However, several mutations were detected repeatedly in individuals of the same ethnic origin. There are no systematic studies concerning mutations in BRCA1 gene in Portugal. The aim of this study is to identify mutations inh this gene in patients with breast and/or ovarian cancer of Portuguese origin. Thirty-three cases of breast cancer and 3 of ovarian cancer were selected according to early age of onset and family history. Mutation screening of this gene was done by Protein Truncation Test (PTT) and Fragment analysis. Two de novo mutations were identified: 1) A frameshift mutation localised in exon 11 of BRCA1, was identify by the two techniques in an ovarian cancer case. Direct sequential revealed a deletion of 4 nucleotides (3444delAAAT); 2) An alteration in intron 18 (IVS 18 + 80delT) was observed in a breast cancer case. This is probably the first description of mutations in a series of patients with breast and/or cancer in the Portuguese population. The mutations identified in this study have not been previously described in other populations according to the Breast Cancer Information Core web site.