MLH1 and hereditary nonpolyposis colon cancer: Since methylation accounts for loss of MLH1 function in up to 90% of sporadic CRC and is uncommon in HNPCC (Wheeler et al, 2000), it is more likely that this patient has developed two sporadic cancers rather than having an underlying germline mutation, suggesting that, on combined immunohistochemistry and MSI analysis, only 26% of patients might have HNPCC.