We characterized 135 participants from the: (1) Applying Novel Genomic approaches to Early-onset and suspected Lynch Syndrome colorectal and endometrial cancers (ANGELS) (n = 76), (2) Colon Cancer Family Registry (CCFR) (n = 38), and (3) Muir-Torre Syndrome (MTS) (n = 21) studies who developed MMR-deficient CRCs (n = 96), ECs (n = 18), or SSTs (n = 21) for germline and somatic MMR pathogenic variants.7 Here, MRC1 is linked to colonic neoplasm.