We found hypermutated tumors in 8% of Japanese patients with CRC and 2% of American patients with CRC, both of which are commonly correlated with DNA mismatch repair deficiency (MMR-D) evaluated by immunohistochemical staining of MMR proteins, such as MLH1, MSH2, MSH6, and PMS2 [37]. The gene discussed is PMS2; the disease is colorectal carcinoma.