A novel MLH1 mutation in a Japanese family with Lynch syndrome associated with small bowel cancer

Lynch syndromeis a genetic disorderrelated to cancer predisposition, including colorectal cancer, endometrial cancer, and ovarian cancer. Germline mutationsin mismatch repair genes, including MLH1, MSH2, MSH6, and PMS2, are responsible for this condition. Cancer tissue specimens resected from small bowel adenocarcinoma in a Japanese patient showed decreased expression of MLH1and PMS2by immunohistochemistrytesting. Finally, a novel MLH1mutation, c.1833dup, was identified in this patient.