MMR deficiency was statistically more frequently associated with a BRAF mutation (41% vs. 6.8%, p < 0.001), a right tumor location (77% vs. 33%, p < 0.001), a higher median age (77.6 years vs. 66.4 years, p = 0.01), a higher female-to-male ratio (68% vs. 45%, p = 0.06), PTEN mutations (18% vs. 1.2%, p = 0.002) and a high number of variants in NGS (number of variants ≥2 in 45% of MMR-deficient patients vs. 20% of MMR-proficient patients, p = 0.015). Here, MRC1 is linked to mismatch repair cancer syndrome 1.