While the majority of dMMR/MSI-H CRCs are sporadic tumors and often caused by the epigenetic methylation of the MLH1 gene promoter or to the acquisition of double somatic mutations in MMR genes, frequently associated with BRAFV600E mutation, only a small percentage of dMMR/MSI-H CRCs (8%) are hereditary tumors, included in the Lynch syndrome, related to germline mutations of MMR genes [17]. Here, MRC1 is linked to Lynch syndrome.