MLH1 and Lynch syndrome: Pathogenic mutations in the DNA mismatch-repair gene MLH1 (MutL homolog 1) are associated with a predisposition to Lynch syndrome (Bronner et al., 1994 ▸; Papadopoulos et al., 1994 ▸), a hereditary cancer syndrome that accounts for 2–4% of all colorectal cancer cases in the US (Aaltonen et al., 1998 ▸; Hampel et al., 2005 ▸, 2008 ▸; Lynch & de la Chapelle, 2003 ▸).