Several substances have been identified as being potentially related to CS manifestations and include mostly amines (serotonin, 5-hydroxytryptophan, norepinephrine, dopamine, histamine), but also many different polypeptides (kallikrein, pancreatic polypeptide, bradykinin, motilin, somatostatin, insulin, S-100 protein, vasoactive intestinal peptide, neuropeptide K, substance P, neurokinins, ACTH, gastrin, growth hormone, peptide YY, glucagon, endorphins, neurotensin, chromogranin A) and prostaglandins [11]. This evidence concerns the gene TAC1 and Cowden syndrome 1.