Multiple Endocrine Neoplasia Type 2 (MEN2)

What causes MEN2?

People with MEN2 are born with a faulty (i.e., disease-causing) RET gene.

When working properly, the RET gene provides instructions to produce a protein involved in signalling within cells. This signalling is needed to ensure normal development and controlled growth of cells.

If there is a fault (i.e., mutation) within the RET gene, it can become dysfunctional, resulting in the production of an overactive protein which can signal cells to grow and divide uncontrollably, resulting in tumour formation and cancer.

The location of the fault within the RET gene can determine the age, likelihood and aggressiveness of the medullary thyroid cancer that may develop. Its management will be based on where the location of the fault is in the RET gene.

Types of MEN2

• MEN2B
  The most severe form of MEN2 is called MEN2B because the gene fault directly impairs RET function. All individuals with MEN2B are considered to be at highest risk.
• MEN2A
  95% of patients with MEN2 have the less severe form called MEN2A.
  

What are the tumour and cancer risks associated with MEN2?

Note: The conditions associated with a faulty RET gene and their risk estimates may change as more information is available.

Depending on your genetic result and personal/family history of cancer, your personal risk levels may differ from the values shown above.

There is a classification system that determines the medullary thyroid cancer risk level based on where the fault in the RET gene is located. It is best to ask your genetics service to understand your risk level in more detail.

Your managing doctors will also advise you on the medical care that might or might not be beneficial for you, according to your risk level.

How is MEN2 inherited?

MEN2 follows a dominant inheritance pattern. This means that having one faulty copy of the RET gene can result in an increased risk of tumours/cancer. It affects both males and females.

Everyone has 2 copies of each gene in their body’s cells:

• 1 copy comes from our father
• 1 copy comes from our mother

A parent with a faulty gene(s) has a 50% chance of passing down their faulty gene(s) to their children. A child, sibling or parent of a family member with a faulty gene(s) has a 50% chance of also inheriting the same faulty gene(s). Extended relatives may also inherit the faulty gene(s).