Up to 30% of colorectal cancer (CRC) cases have a hereditary basis, with an estimated 5% of CRC occurring due to a genetically defined high‐risk CRC syndrome involving pathogenic germline mutations in APC (OMIM 611731), MUTYH (OMIM 604933), and DNA mismatch repair (MMR) genes (MLH1 (OMIM 120436), MSH2 (OMIM 609309), MSH6 (OMIM 600678), EPCAM (OMIM 185535), and PMS2 (OMIM 600259)). The gene discussed is MSH2; the disease is colorectal carcinoma.