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. This evidence concerns the gene PTEN and Familial adenomatous polyposis.