Large genomic deletions inactivate the BRCA2 gene in breast cancer families

Background: BRCA1 and BRCA2 are the two major genes responsible for the breast and ovarian cancers that cluster in families with a genetically determined predisposition. However, regardless of the mutation detection method employed, the percentage of families without identifiable alterations of these genes exceeds 50%, even when applying stringent criteria for family selection. A small but significant increase in mutation detection rate has resulted from the discovery of large genomic alterations in BRCA1. A few studies have addressed the question of whether BRCA2 might be inactivated by the same kinds of alteration, but most were either done on a relatively small number of samples or employed cumbersome mutation detection methods of variable sensitivity. Objective: To analyse 121 highly selected families using the recently available BRCA2 multiplex ligation dependent probe amplification (MLPA) technique. Results: Three different large genomic deletions were identified and confirmed by analysis of the mutant transcript and genomic characterisation of the breakpoints. Conclusions: Contrary to initial suggestions, the presence of BRCA2 genomic rearrangements is worth investigating in high risk breast or ovarian cancer families.