Loss‐of‐function mutations in RAD51D predispose individuals to ovarian cancer but not to breast cancer.44 Germline RAD51D mutations were found in 0.8% of subjects with ovarian cancer not selected for a family history of ovarian cancer.48 When treated with RNA interference targeting RAD51D, tumour cells exhibit a sensitivity to olaparib similar to that achieved by the silencing of BRCA2.44 RAD51C acts sequentially with RAD51 at the DNA damage site to repair DNA damage, and RAD51C depletion leads to impaired RAD51 foci formation, resulting in impaired DNA repair. This evidence concerns the gene RAD51 and breast cancer.