Taken together with other identified genetic modifiers, 10 loci are now known to be associated with breast cancer risk for BRCA1 mutation carriers (1q32, 10q25.3, 19p13, 6q25.1, 12p11, TOX3, 2q35, LSP1, RAD51L1 and TERT and seven loci are known to be associated with ovarian cancer risk for BRCA1 mutation carriers (9p22, 8q24, 3q25, 17q21, 19p13 and 17q21.31, 4q32.3). This evidence concerns the gene TOX3 and breast cancer.