Immunohistochemistry to detect the expression of MMR proteins such as MLH1, MSH2, MSH6 and PMS2 in tumour tissue is perhaps the most widely used, and has excellent sensitivity (85–98%) and specificity (85–100%).31,32 Polymerase chain reaction-based methods are also commonly used to detect MSI by examining fragment lengths across a panel of loci that are commonly altered in these tumors.33 Here, MLH1 is linked to neoplasm.