MLH1 and Lynch syndrome: It is characterised by an autosomal dominant mode of inheritance and by a highly increased risk of CRC and endometrial cancer, as well as to a lesser extent of some other cancers (eg, ovary, stomach, small intestine, biliary and urinary tract).4 Germline pathogenic variants in the main DNA mismatch repair (MMR) genes, MLH1, MSH2, MSH6 and PMS2, explain the majority of Lynch syndrome cases.