The prevalence of MLH1 constitutional epimutations in colorectal cancers lacking MLH1 expression and showing MLH1 methylation in tumor tissue was reported to be 0 % among unselected cases and 16 % among cases fulfilling the revised Bethesda criteria [21], suggesting that testing for MLH1 epimutations should regularly be restricted to the latter group of patients [45]. Here, MLH1 is linked to colorectal cancer.