MRC1 and colorectal carcinoma: Three CRC-based LS diagnostic strategies were evaluated: the sequencing of all MMR genes without prior tumor analysis (Strategy 1), a sequential IHC and MS-MLPA analysis (Strategy 2), and an age-targeted strategy with a revised Bethesda criteria assessment before IHC and MS-MLPA for patients ≥ than 70 years old (Strategy 3).