Using non-overlapping risk groups, mutation of BRCA1 or BRCA2 genes were identified in 35 (6.4%) of 550 early onset patients, in 5 (7.5%) of 67 patients with bilateral breast cancer, in 2 (40.0%) of 5 patients with breast and ovarian cancer, in 1 (6.7%) of 15 male breast cancer patients, and in 3 (7.0%) of 42 patients with multiple organ cancers including breast. Here, BRCA1 is linked to breast cancer.