Large genomic rearrangements of both BRCA2 and BRCA1 are a feature of the inherited breast/ovarian cancer phenotype in selected families.

INTRODUCTION A strong family history of breast and/or ovarian cancer can often be explained by small insertions, deletions, or substitutions in BRCA1 or BRCA2 and large genomic rearrangements in BRCA1. However, there is little evidence that genomic rearrangements are a major factor in BRCA2 associated breast cancer and the frequencies of rearrangements in BRCA1 in large clinic based populations are unknown. OBJECTIVE To investigate the frequency of large genomic rearrangements in BRCA1 and BRCA2 in a large clinic based population at high risk of developing breast and/or ovarian cancer. METHODS Multiplex ligation dependent probe amplification was used to comprehensively screen BRCA1 and/or BRCA2 in 312 index cases. RESULTS Three novel deletions detected in BRCA2 were found exclusively in families with at least one case of male breast cancer. Novel rearrangements in BRCA1 were detected mostly in families with both breast and ovarian cancer. Families with these mutations were significantly younger at average age of cancer diagnosis. CONCLUSION Screening for large genomic rearrangements in both BRCA1 and BRCA2 is strongly supported by this study, in particular in multiple case breast/ovarian families with a young age of onset (BRCA1) and families containing at least one case of male breast cancer (BRCA2).