MSH2 and Lynch syndrome: Lynch syndrome is a cancer predisposition syndrome caused by heterozygous germline mutations in DNA mismatch repair (MMR) genes, including mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), MSH6, PMS1 homolog 2 (PMS2), and epithelial cell adhesion molecule (EPCAM) [1–3].