BRCA1 and breast cancer: The human breast cancer type1 susceptibility protein (BRCA1) (FA alias FANCS) and breast cancer type 2 susceptibility protein (BRCA2) (FA alias FANCD1) are the most important hereditary breast cancer genes, as identified by linkage studies in 1994 and 1995, respectively (Hall et al., 1990; Miki et al., 1994; Wooster et al., 1994, 1995).