title: Significant contribution of large BRCA1 gene rearrangements in 120 French breast and ovarian cancer families.
abstract: Genetic linkage data have shown that alterations of the BRCA1 gene are responsible for the majority of hereditary breast-ovarian cancers. However, BRCA1 germline mutations are found much less frequently than expected, especially as standard PCR-based mutation detection approaches focus on point and small gene alterations. In order to estimate the contribution of large gene rearrangements to the BRCA1 mutation spectrum, we have extensively analysed a series of 120 French breast-ovarian cancer cases. Thirty-eight were previously found carrier of a BRCA1 point mutation, 14 of a BRCA2 point mutation and one case has previously been reported as carrier of a large BRCA1 deletion. The remaining 67 cases were studied using the BRCA1 bar code approach on combed DNA which allows a panoramic view of the BRCA1 region. Three additional rearrangements were detected: a recurrent 23.8 kb deletion of exons 8-13, a 17.2 kb duplication of exons 3-8 and a 8.6 kb duplication of exons 18-20. Thus, in our series, BRCA1 large rearrangements accounted for 3.3% (4/120) of breast-ovarian cancer cases and 9.5% (4/42) of the BRCA1 gene mutation spectrum, suggesting that their screening is an important step that should be now systematically included in genetic testing surveys.
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics*; D005260:Female; D015321:Gene Rearrangement; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction