Although MSI-NGS can be coupled to the sequencing of MMR genes to identify mutations associated with Lynch syndrome, neither MSI-NGS nor MSI-PCR can identify the loss of expression of an MMR protein: MMR-IHC, possibly associated with the search for MLH1 promoter hypermethylation, remains essential in order to distinguish sporadic dMMR from Lynch syndrome [6]. Here, MRC1 is linked to Lynch syndrome.