Microsatellite instability-high (MSI-H) CRC, a cancer characterized by the absence of one or two mismatch repair (MMR) proteins such as MSH2, PMS2, MLH1, and MSH6 have been reported to be immunogenic with robust lymphocytic infiltrate due to increased mutational signatures [34] and this may be more frequent in CRC with mucinous histology. The gene discussed is PMS2; the disease is colorectal carcinoma.