Multiple Endocrine Neoplasia Type 1 and Type 4

Multiple Endocrine Neoplasia (MEN) syndromes are characterised by the combined occurrence of two or more endocrine tumours in a patient. These autosomal dominant conditions occur in four types: MEN type1 due to inactivating MEN1 gene mutations; MEN type 2A and MEN type 2B (also known as MEN type 3) due to activating mutations of the “rearranged during transfection” (RET) proto-oncogene; and MEN type 4 due to inactivating Cyclin-Dependent Kinase Inhibitor 1B (CDKN1B) mutations. Each MEN syndrome exhibits different combinations of pancreatic islet, anterior pituitary, parathyroid, medullary thyroid and adrenal endocrine tumours together with associated non-endocrine tumours. This chapter provides an overview of the clincial features, diagnosis, treatments and molecular genetics of Multiple Endocrine Neoplasia syndromes types 1 and 4.