BRCA1 and breast cancer: The lifetime risk of breast cancer in female germline BRCA variant carriers is up to 85%; the lifetime risk of ovarian cancer is up to 50% [2, 6, 8, 11, 33, 34, 36, 38] Genetic alterations in the BRCA1/2 genes cause over 90% of cases of HBOC [6, 33, 34, 36].