PTEN and Lynch syndrome: Further evidence for this view comes from cancer predisposition syndromes with a tumor spectrum including tumors of the gastrointestinal tract and the nervous system, e.g. Cowden, Li-Fraumeni, Lynch syndromes, familial adenomatous polyposis [30], and familial intestinal gastric cancer [11], suggesting that pathogenic germline variants in the underlying genes, e.g. PTEN, TP53, MSH2, MSH6, MLH1, PMS2, APC, cause tumors in both organ systems.