Specifically, 19 suspected LS patients with a strong personal and/or family LS-related cancer history meeting the Amsterdam or Bethesda criteria were analyzed to evaluate genetic alterations in MMR genes (MLH1, MSH2, MSH6, and PMS2) and the EPCAM gene, while the remaining 11 suspected LS patients, who had a personal but not a family cancer history and/or had a family history of cancers potentially correlated to other major hereditary tumor predisposition syndromes, were subjected to genetic analysis of 25 genes involved in major hereditary cancer predisposition syndromes by NGS. This evidence concerns the gene PMS2 and Leigh syndrome.