Germline mutations in the breast cancer genes BRCA1 and BRCA2 are related to an increased risk for breast, ovarian and other cancers in a syndrome known as hereditary breast and ovarian cancer (HBOC) which accounts for most cases of hereditary breast cancer (HBC) worldwide (Miki et al., 1994; Wooster et al., 1994; Peto et al., 1999; Anglian Breast Cancer Study Group, 2000; Antoniou et al., 2000, 2002). The gene discussed is BRCA2; the disease is breast cancer.