Our results are consistent with several published research reports, showing evidence of APC being the most frequently mutated gene detected in early-onset CRC patients [19,22,23]. Further analysis of the immunohistochemical staining of the four main DNA mismatch-repair (MMR) genes, the microsatellite instability (MSI) testing, or MLH1 hypermethylation analysis, is required to confirm the diagnosis of the PMCRC9 patient. This evidence concerns the gene MLH1 and colorectal carcinoma.