MLH1 and cancer: Three main etiologically distinct subgroups have been identified in dMMR cancers: The Lynch subgroup (pathogenic/likely pathogenic germline mutations in any of MLH1, MSH2, MSH6, PMS2, EPCAM); the MLH1-hypermethylated group (MLH1 promoter hypermethylation without MLH1 germline mutations); and the Lynch-like subgroup (neither MMR gene germline mutations nor MLH1 promoter hypermethylation) (6).