Endocrine Neoplasia Syndromes

The multiple endocrine neoplasia (MEN) syndromes are a group of hereditary disorders characterized by the development of tumors in two or more endocrine glands; patients may also express nonendocrine manifestations. A number of additional similar disorders, which are not recognized as MEN, also occur with distinct features, and these are referred to here as the multiple endocrine and other organ neoplasia (MEON) syndromes. The majority of MEN and MEON syndromes are inherited as autosomal-dominant traits that result from pathogenic DNA variants in their respective causative genes, although in some instances a relevant family history may not be evident. Frequently, these disorders present in children or young adults, although the possibility of such a disorder should be considered in all patients presenting with relevant clinical manifestations. Indeed, the recognition of these disorders is not only important to allow the most appropriate management of the patient, but in many settings, it facilitates cascade genetic testing of family members who may be at risk of disease. Both diagnostic and predictive genetic testing form an important part of clinical management, with the aim of identifying those at risk of disease who may benefit from disease-specific treatment and/or regular surveillance. The management of each of the respective conditions requires a multidisciplinary approach over the patient’s lifetime, with the aim of reducing disease-associated morbidity and mortality while preserving the patient’s quality of life. Understanding of the genetic and molecular basis of these rare disorders has provided fundamental insights into the mechanisms of hereditary and sporadic endocrine tumorigenesis and is facilitating the development of novel personalized treatment approaches.