MLH1 and colorectal carcinoma: In the screening of Lynch syndrome, analysis of microsatellite instability(MSI) and immunohistochemistry of mismatch-repair proteins showed that 10–15% CRC cases were MSI-high or had deficient MMR proteins.[8–11] Overall 2–3% CRC cases were found to have germline mutations in the mismatch repair system.(8,9,12) Hypermethylation of the MLH1 gene promoter resulting in silence of MMR proteins is another cause of MSI-high [12–14].