Lynch Syndrome (LS) is an autosomal dominant cancer syndrome, caused by pathogenic variants in genes involved in DNA mismatch repair: MLH1, MSH2, MSH6, and PMS2. LS confers a significant increase in an individual’s cancer risk, with lifetime risk reaching some 80% in carriers of pathogenic variants of MLH1 and MSH2 [1]. This evidence concerns the gene PMS2 and Leigh syndrome.