BRCA1 mutations were detected in 22 (3.5%) of 625 early onset patients, in 7 (5.6%) of 124 patients with bilateral breast cancer, in 1 (16.7%) of 6 patients with breast and ovarian cancers, in 2 (3.0%) of 66 patients with multiple organ cancers, and in 7 (8.9%) of 79 patients having two or more of these high-risk factors. This evidence concerns the gene BRCA1 and breast cancer.