Multiple Endocrine Neoplasia Type 1

Multiple endocrine neoplasia type 1 (MEN1) is a rare endocrine tumor syndrome with high penetrance. This syndrome is also known as Wermer syndrome. It primarily causes neoplasia of the parathyroid glands, the anterior pituitary gland, and the neuroendocrine tissue of gastro-entero-pancreatic organ systems. Hyperparathyroidism is the most common manifestation and occurs in 90% of cases. Similarly, pancreatic neuroendocrine tumors occur in 60% of cases, while pituitary adenomas occur in 40% of cases. The affected patient, however, may also develop less common endocrine and non-endocrine tumors such as carcinoid tumors of the thymus, bronchus, or stomach, adrenocortical tumors, cutaneous tumors, central nervous system (CNS) tumors, leiomyomas, lipomas, collagenomas, and angiofibromas. MEN1 gene testing in an index case can confirm the diagnosis and allow early detection of asymptomatic mutation carriers years before a MEN1-associated tumor can be detected. However, approximately 20% of MEN1 kindred have no mutation in the MEN1 gene. Unfortunately, there is no genotypic-phenotypic correlation in MEN1, leading to different manifestations even among family members. Studies have demonstrated that nonsense and splicing mutations are associated with more aggressive neuroendocrine tumors.