Multiple endocrine neoplasia type 2B

What causes multiple endocrine neoplasia type 2B (MEN2B)?

Multiple endocrine neoplasia type 2B (MEN2B) is caused by certain genetic changes (mutations or pathogenic variants) in the RET gene. This gene provides instructions to the body to make a protein that helps regulate the growth and division of cells of the endocrine system. This protein is supposed to tell the body when it is appropriate to allow the cells of the endocrine system to divide. When there is a pathogenic variant in the RET gene, the cells of the endocrine system are able to grow and divide out of control. This causes the signs and symptoms of MEN2B, as well as the increased risk for the development of tumors.

About 95% of people who have MEN2B have a pathogenic variant in one particular area of the RET gene known as codon 918. Genetic changes in this region of the RET gene are thought to cause the RET gene to be more highly activated than other genetic changes within the RET gene. This is why MEN2B causes a higher risk for tumor development at a younger age as compared to other pathogenic variants in the RET gene.

Last updated on 05-01-20

How is multiple endocrine neoplasia type 2B (MEN2B) diagnosed?

Multiple endocrine neoplasia type 2B (MEN2B) is suspected when a doctor sees a person who has a personal or family history of medullary thyroid carcinoma or pheochromocytoma. The diagnosis may also be suspected based on physical features suggestive of MEN2B such as having bumps on the eyelids or lips and long arms, legs, fingers, and toes. The diagnosis of MEN2B can be confirmed with genetic testing of the RET gene.

Last updated on 05-01-20

How is multiple endocrine neoplasia type 2B (MEN2B) inherited?

Multiple endocrine neoplasia type 2B (MEN2B) is inherited in an autosomal dominant manner. This means that a person only needs one copy of the RET gene to have a change (mutation or pathogenic variant) causing MEN2B. We inherit one copy of every gene from our mother and the other from our father. When a person who has MEN2B has children, for each child there is a:

  • 50% chance that the child will inherit the copy of the RET gene with a pathogenic variant, meaning he or she will have MEN2B
  • 50% chance that the child will inherit the working copy of the RET gene, meaning he or she will not have MEN2B

In some cases, people who have MEN2B are the first people to be diagnosed in the family. This may be because they inherited the genetic change from a parent, but the parent was never diagnosed with the disease. In other cases, the genetic change may be new in the person who was diagnosed with MEN2B. Genetic changes that are new in a person are called de novo. It is estimated that about 50% of people with MEN2B have a genetic change that is de novo.

Last updated on 05-01-20

What is the long-term outlook for people affected with multiple endocrine neoplasia type 2B (MEN2B)?

The long-term outlook for people with multiple endocrine neoplasia type 2B (MEN2B) may depend upon when a person with the disease was diagnosed. If the disease is identified early, prior to the development of a medullary thyroid carcinoma, the thyroid can be removed. Because medullary thyroid cancer often metastasizes, spreading cancer to other tissues in the body, removal of the thyroid (thyroidectomy) greatly reduces the chances that a person with MEN2B develops cancer. The other types of tumors which develop in people with MEN2B are usually not cancerous (benign) and therefore do not tend to be life-threatening.

If a person is diagnosed with MEN2B after he or she has already developed medullary thyroid carcinoma, the thyroid can be removed. If the cells of the tumor have already spread to other parts of the body (metastasized), surgery may not be able to remove all of the cancer. This can increase the risk for a person to pass away from the disease.

Other symptoms of MEN2B, such as gastrointestinal symptoms, are not life- threatening but can impact a person’s quality of life.

Last updated on 05-01-20

How might multiple endocrine neoplasia type 2B (MEN2B) be treated?

People with multiple endocrine neoplasia type 2B (MEN2B) are recommended to have their thyroid removed (thyroidectomy) as soon as they are diagnosed. This is because the risk for medullary thyroid carcinoma is nearly 100% in people who have MEN2B, and a thyroidectomy can prevent a person from ever developing medullary thyroid carcinoma.

After the thyroid is removed, a person with MEN2B may still have tests to make sure a medullary thyroid carcinoma did not develop and spread before the thyroid was removed. If the medullary thyroid carcinoma cannot be completely removed, there are therapies available such as tyrosine kinase inhibitors. These therapies can slow the growth of medullary thyroid carcinomas. People who have thyroidectomies need to take medications that contain the hormones that are normally produced by the thyroid.

People with MEN2B may also be recommended to have frequent tests such as analysis of the blood or urine for signs that there may be a tumor in the adrenal glands(pheochromocytoma). Imaging tests such as MRI or CT scan can also be used to monitor for the development of a pheochromocytoma. If a pheochromocytoma is identified, it may be removed with surgery.

Last updated on 05-01-20

Name: Association for Multiple Endocrine Neoplasia Disorders (AMEND) UK, New Zealand, and USA The Warehouse No 1 Draper Street
Southborough Tunbridge Wells Kent TN4 0PG
United Kingdom
Phone: + 44 (0)1892 516076 Email: info@amend.org.uk Url: http://www.amend.org.uk
Name: American Multiple Endocrine Neoplasia Support 1027 Hampshire Drive
Maryville, TN, 37801,
Phone: 865-238-5842 Email: http://amensupport.org/contact%20us Url: http://www.amensupport.org/
Name: Rare Cancers Australia PO Box 440
Bowral New South Wales, 2576, Australia
Phone: +61 2 4862 276 Email: contact@rarecancers.org.au Url: http://rarecancers.org.au/

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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