Multiple endocrine neoplasia type 2A
Overview
Multiple endocrine neoplasia type 2 is a group of medical disorders associated with tumors of the endocrine system. The tumors may be benign or malignant (cancer). They generally occur in endocrine organs (e.g. thyroid, parathyroid, and adrenals), but may also occur in endocrine tissues of organs not classically thought of as endocrine.
Causes
The table in the multiple endocrine neoplasia article lists the genes involved in the various MEN syndromes. Most cases of MEN2 derive from a variation in the RET proto-oncogene, and are specific for cells of neural crest origin. The protein produced by the RET gene plays an important role in the TGF-beta (transforming growth factor beta) signaling system. Because the TGF-beta system operates in numerous tissues throughout the body, variations in the RET gene can have effects in numerous tissues throughout the body.
Diagnosis
Diagnosis of MEN type 2B is made clinically by the presence of: * mucosal neuromas of the lips and tongue * medullated corneal nerve fibres in the eye * distinctive facies with enlarged lips * asthenic “Marfanoid” body habitus * medullary carcinoma of the thyroid Molecular genetic testing can be used to confirm the diagnosis, for predictive testing and for prenatal diagnosis.
Treatment
Individuals with MEN type 2B disease should have their thyroid gland removed at a very early age (around 1 year) to reduce the risk of thyroid cancer. Compared with other types of thyroid cancer, medullary carcinoma of the thyroid is a very aggressive cancer. If the thyroid is not removed in childhood, the average age of death in people with MEN type 2B disease is around 21 years. Once the thyroid is removed, patients must take thyroid hormone replacements (thyroxine) for the rest of their life. There is no known cure for any of the MEN syndromes. Patients are treated for their symptoms. Annual urine biochemical screening for phaeochromocytoma is recommended for all patients. Genetic testing is also important for people with a family history of the disease as early diagnosis and treatment will reduce the risk of thyroid cancer and death.