This small difference could be explained by the commonly used Bethesda panel for the detection of MSI, which has only been validated in CRC and not EC.79 In addition, MSH6 deficient EC can be microsatellite low or stable.80 That said, IHC does enable a more targeted application of MLH1 promoter hypermethylation testing, given that it need only be applied to MLH1 deficient tumors. The gene discussed is MSH6; the disease is colorectal carcinoma.