In conclusion, sequencing of the entire genomic region of 15 CRC susceptibility genes in 34 unrelated sLS patients and 11 patients with MLH1 hypermethylated tumors, together with assessment of somatic variants, provides a broad impression of possible genetic causes of tumor formation in MSI-H and/or MMR-deficient tumors. This evidence concerns the gene MLH1 and colorectal carcinoma.