The gastrin, which is the hormone overexpressed by this tumor, is responsible for a clinical syndrome known as Zollinger-Ellison syndrome (ZES) characterized by gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), and diarrhea with good response to proton pomp inhibitors (PPI) therapy [11]. The gene discussed is GAST; the disease is Zollinger-Ellison syndrome.