MLH1 and Leigh syndrome: The cancer-predisposing Lynch syndrome (LS) is an autosomal dominant disorder caused by germline mutations in the MMR pathway genes, mainly mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), mutS homolog 6 (MSH6), epithelial cell adhesion molecule (EPCAM), and post-meiotic segregation increased 2 (PMS2) (3, 4).