Germline mutations in BRCA1 and BRCA2 in epithelial ovarian cancer patients in Brazil

Abstract

AbstractBackground. Approximately 8-15% epithelial ovarian cancer patients are BRCA1 or BRCA2 germline mutation carriers. Brazilian inhabitants may have peculiar genetic characteristics associated with ethnic diversity, and studies focusing on the entire BRCA1/BRCA2 gene sequencing in Brazilian ovarian cancer patients are still lacking. The aim of this study was to evaluate BRCA1/2 mutations, through entire gene sequencing, in a Brazilian population of women with epithelial ovarian cancer.Methods. In a cross sectional study performed in one reference centre for cancer treatment in São Paulo, Brazil, 100 patients diagnosed with epithelial ovarian cancer unselected for family history of breast and/or ovarian cancer were included. The complete coding sequence of BRCA1/2 genes was evaluated through Next-Generation or capillary sequencing. Large deletions were investigated through Multiplex Ligation-dependent Probe Amplification (MLPA).Results. Nineteen pathogenic mutations (BRCA1: n=17 and BRCA2: n=2) featuring 14 different mutations, including two large deletions in BRCA1 (exon 1-2 deleted and exon 5-7 deleted) were identified. Three mutations were detected more than once (c.3331_3334delCAAG, c.5266dupC and c.4484G>T). Two novel frameshift mutations were identified, one in BRCA1 (c.961_962delTG) and one in BRCA2 (c.1963_1963delC). BRCA1/2 mutations were seen in 35.5% of the patients with first and/or second-degree relatives with breast and/or ovarian cancer. Nineteen variants of uncertain significance (VUS) were detected (BRCA1: n=2 and BRCA2: n=17), including five distinct missense variants (BRCA1: c.5348 T>C; BRCA2: c.2350A>G, c.3515C>T, c.7534C>T, and c.8351G>A).Conclusions. Among epithelial ovarian cancer patients unselected for family history of cancer, 19% were BRCA1/2 germline mutation carriers. Almost ¾ of the BRCA mutations, including two large deletions, were detected only once. Our work emphasizes the need of entire gene sequencing and MLPA screening in Brazil. (AU)