Many of the medical and scientific terms used in this summary are found in the NCI Dictionary of Genetics Terms. When a linked term is clicked, the definition will appear in a separate window.
Many of the genes described in this summary are found in the Online Mendelian Inheritance in Man (OMIM) database. When OMIM appears after a gene name or the name of a condition, click on OMIM for a link to more information.
Clinical validity refers to the predictive value of a test for a given clinical outcome (e.g., the likelihood that cancer will develop in someone with a positive test). It is primarily determined by the sensitivity and specificity with which a test identifies people with a defined clinical condition within a given population. Sensitivity of a test refers to the proportion of people who test positive for a clinical condition among those who actually have the clinical condition; specificity refers...
There are several hereditary syndromes that involve endocrine or neuroendocrine glands, such as multiple endocrine neoplasia type 1 (MEN1), multiple endocrine neoplasia type 2 (MEN2), pheochromocytoma, paraganglioma, and von Hippel-Lindau syndrome. This summary currently focuses on MEN1, MEN2, and familial paraganglioma. Additional sections are in progress.
The term multiple endocrine neoplasia is used to describe a group of heritable tumors of endocrine tissues that may be benign or malignant. They are typically classified into two main categories: MEN1 and MEN2. The tumors usually manifest themselves by overproduction of hormones, tumor growth, or both.
Comprising varying combinations of more than 20 endocrine and nonendocrine tumors, MEN1 may be a difficult syndrome to define clinically. In general, however, MEN1 is characterized by tumors of the parathyroids, pancreas, and pituitary gland. This syndrome may also include carcinoid tumors, adrenocortical tumors, and nonendocrine tumors, such as facial angiofibromas, collagenomas, lipomas, meningiomas, ependymomas, and leiomyomas.
MEN1 syndrome, also known as Wermer syndrome, results from a mutation in the MEN1gene. It has a prevalence of about 1 in 30,000 individuals.
MEN2 is caused by a mutation in the RET proto-oncogene. Historically, MEN2 has been further stratified into the following three subtypes based on the presence or absence of certain endocrine tumors in the individual or family:
All three subtypes of MEN2 (MEN2A, FMTC, and MEN2B) impart a high risk of developing medullary thyroidcancer (MTC). MEN2A has an increased risk of pheochromocytoma and parathyroid adenoma and/or hyperplasia. MEN2B has an increased risk of pheochromocytoma and includes additional clinical features, such as mucosal neuromas of the lips and tongue, distinctive faces with enlarged lips, ganglioneuromatosis of the gastrointestinal tract, and an asthenic Marfanoid body habitus. FMTC has been defined as the presence of at least four individuals with MTC without any other signs or symptoms of pheochromocytoma or hyperparathyroidism in the proband or other family members.