The data both from the two large NIH studies reviewed above on gastric ECL changes in sporadic ZES [25] and MEN1/ZES [61] patients, as well as from the literature, demonstrate that chronic hypergastrinemia in MEN1/ZES patients is associated with more advanced ECL cell proliferative stages the seen in sporadic ZES patients, as well as a marked increase in the occurrence of gastric carcinoid tumors. The gene discussed is MEN1; the disease is gastric neuroendocrine tumor G1.