All human miRNA genes containing mononucleotide (MNR) or dinucleotide repeats (DNR) (≥7 repeats) in their hairpin sequences were screened for mutations (nucleotides additions/deletions) using a large series of MMR-deficient CRC cell lines and primary tumors, as well as lymphoblastoid cell lines (LBLs) and MSS CRC controls enabling the assessment of the polymorphic status of these sequences. This evidence concerns the gene MRC1 and colorectal carcinoma.