MRC1 and cancer: When compared with MMR IHC34, 37, 50 and MSI analysis,13, 36 the sensitivity of detecting LS is equivalent to MSI analysis when using four MMR proteins for IHC.51 Approximately 3% of the cases were discordant in these two methods, and 5% of cancers that demonstrated MSI had normal MMR protein expression,52, 53 while some tumors with pathogenic variants of g.MSH6 revealed microsatellite stability,33 like case 3 in the current study (Table 2).