MLH1 and Leigh syndrome: Approximately 5% of CRCs are associated with germline variants, and Lynch syndrome (LS) is the most prevalent cause of hereditary CRC and is an autosomal dominant disorder related to monoallelic germline pathogenic variants (GPVs) in DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2, and deletions in the EPCAM gene (2–4).