MSI CRC occurs in approximately 15–16% of CRC due to inactivation of the DNA Mismatch Repair (MMR) system (MLH1, MSH2, MSH6, PMS2), with the majority (12%) presenting as sporadic MSI CRC as a result of epigenetic mutation (methylation silencing) of the promoter sequence of MLH1, and BRAF V600E oncogenic mutations2,6–10. Here, MLH1 is linked to colorectal carcinoma.