Germline mutations in MMR genes can give rise to Lynch syndrome (LS), an autosomal-dominant cancer predisposition syndrome that increases the risk for several forms of malignancy, including colorectal (lifetime cancer risk, 70%–80%), endometrial (50%–60%), stomach cancer (13%–19%), and ovarian cancer (9%–14%). The gene discussed is MRC1; the disease is ovarian carcinoma.