If risk-reducing BSO had been performed at 25 years of age, this would have prevented the observed risks of ovarian cancer to age 50 years of 6%, 11%, 2%, and 0% in patients with heterozygous path_MLH1, path_MSH2, path_MSH6, and path_PMS2 variants, respectively. The gene discussed is PMS2; the disease is ovarian cancer.