Chapter 62 - Multiple Endocrine Neoplasia Type 1

Abstract

This chapter deals with multiple endocrine neoplasia type 1 (MEN1) syndrome, which is a rare disorder presenting with varying combinations among its three main endocrine tumors (parathyroid entero-pancreatic, and pituitary), but includes a varying combination of more than 20 endocrine and nonendocrine tumors. Other endocrine and nonendocrine neoplasms such as foregut carcinoids, lipomas, and skin tumors are also common in MEN1. Furthermore, other endocrine and nonendocrine tissues can be affected but with a lower frequency. Familial MEN1 syndrome is defined as MEN1 syndrome in an individual who has at least one first-degree relative with at least one of the three main endocrine tumors. The clinical aspects of MEN1 include MEN1 variants and MEN1 phenocopies. The MEN1 tumors differ from common tumors. This is explained in the study. Primary hyperparathyroidism is the most common endocrinopathy in MEN1, reaching nearly 100% by age 50 and it is usually the first endocrine manifestation of MEN1 syndrome in 90% of individuals. The discovery of the MEN1 gene has led to changes in clinical management and to new insights about normal and abnormal functions. More studies are necessary to clearly elucidate the molecular mechanisms underlying MEN1-associated tumorigenesis. New tools are in place to answer many questions shortly. Similarly, there are prospects for novel treatments based upon DNA, RNA, or even other small molecules.