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The multiple endocrine neoplasia (MEN) syndromes are a group of genetically inherited diseases. It affects the body's network of hormone-producing glands called the endocrine system. MEN typically involves tumoours (neoplasia) in at least two endocrine glands; tunours can also develop in other organs and tissues. These groths can be noncancerous (benign) or cancerous (malignant). If the tumours become cancerous, the condition can be life threatening. Cancer may arise in multiple organs at the same time, or a person may develop one cancer, then a second cancer in another organ, many years later. These cancers also often arise in younger people and may be more aggressive than ‘sporadic’ cancers – those that do not have a genetic inheritance pattern.
The major forms of multiple endocrine neoplasia are called type 1, and type 2. These types are distinguised by the genes involved, the types of hormones made, and the characteristic signs and symptoms.
Type 1 is the most common and affects approximately 1 in 30,000 and is caused by a heritable defect in the MEN-1 tumour suppressor . If one of your parents has this syndrome, you have a 50 per cent chance of having the syndrome yourself. The syndrome most commonly affects the parathyroid gland (four small glands on the front of your thyroid), pancreas and pituitary gland (a small gland at the base of your brain). Tumours in these glands can lead to the overproduction of hormones. However, a patient with MEN-1 may also develop cancer of the small intestines, and lipomas (fatty lumps on your skin).
Multiple endocrine neoplasia type 2 is divided into three subtypes: type 2A, type 2B (formerly called type 3), and familial medullary thyroid carcinoma (FMTC). In this syndrome there is a genetic mutation in the 'RET proto-oncogene' (see RET gene mutation). Among the subtypes of type 2, type 2A is the most common form, followed by FMTC. Type 2 A affects approximately 1 in 35,000 people. Type 2B is relatively uncommon, accounting for about 5 per cent of all cases of type 2.
- Type 2A people develop medullary thyroid cancer (MTC), and an over-active parathyroid gland.
- Type 2B is characterised by MTC, phaeochromocytoma and cancer on the lips or tongue.
Last Review Date: September 7, 2019
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