MLH1 and Lynch syndrome: MSI-high (MSI-H) is observed in almost 15% of the colon cancers and is characterized by inactivation of DNA mismatch repair genes either by germ line mutations in MLH1, MSH2, MSH6, and PMS2 genes (inherited colon cancer syndrome known as the Lynch syndrome; [19]) or by the somatic promoter hypermethylation of the MLH1 gene (sporadic colorectal cancer with MSI-H [20]).