MLH1 and adenocarcinoma: In the serrated pathway, which occurs in 10% to 20% of the cases, the normal mucosa evolves into sessile serrated lesions (SSL) often with mutations in the BRAF proto-oncogene, followed by the development into an adenocarcinoma through MutL homolog 1 (MLH1) promoter methylation leading to microsatellite instability (MSI).