From 5% to 10% of breast cancer cases result from an inherited predisposition. The majority of hereditary breast and ovarian cancer can be accounted for by mutation in BRCA1 and BRCA2 in transcription regulation. Although this role could be consistent with the reported localisation of the BRCA1/BRCA2 protein to the nucleus. The BRCA1 and BRCA2 may play an as yet undefined protective role in cells, as it is expressed in epithelial cells undergoing high levels of proliferation associated with differentiation.