MSH6 and Familial adenomatous polyposis: Examples of autosomal dominant Mendelian CRC syndromes are Lynch syndrome (LS) caused by mutations in the mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2, familial adenomatous polyposis (FAP) caused by mutations in the APC gene and polymerase proofreading-associated polyposis (PPAP) caused by mutations in the exonuclease domain of the POLE or POLD1 genes.