The incidence of MEN1 has been estimated from randomly chosen postmortem studies to be 0.25% and to be 1–18% among patients with primary hyperparathyroidism, 16–38% among patients with gastrinomas, and less than 3% among patients with pituitary tumors (Thakker, 2010). The gene discussed is MEN1; the disease is gastrin-producing neuroendocrine tumor.