MSH2 and Leigh syndrome: LS is an inherited autosomal dominant cancer-susceptibility disorder derived from germline pathogenic variants in four DNA mismatch repair (MMR) genes: mutL homologue 1 (MLH1), mutS homologue 2 and 6 (MSH2 and MSH6, respectively), and postmeiotic segregation increased 2 (PMS2) [66,67,68].