Germline mutations in the BRCA1 (MIM#113705) and BRCA2 (MIM#600185) genes account for genetic predisposition and increased risk for breast and ovarian cancer in the majority of families with inherited predisposition to both these neoplasms and in 20–40% of families with site-specific breast cancer (Hall et al, 1990; Easton et al, 1993; Frank et al, 1998). The gene discussed is BRCA1; the disease is breast cancer.