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Multiple endocrine neoplasia type 2A
MEN2A is a rare inherited condition that primarily affects the thyroid, adrenal, and parathyroid glands. It leads to a higher chance of developing specific tumours, which can be identified and managed through regular surveillance.
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Overview
Multiple Endocrine Neoplasia Type 2A, often referred to as MEN2A, is a rare inherited disorder characterised by an increased risk of developing specific types of tumours. These growths primarily affect the endocrine glands, which are responsible for producing hormones that regulate many body functions. The main tumours associated with MEN2A include medullary thyroid carcinoma, phaeochromocytoma, and primary hyperparathyroidism.
MEN2A is a lifelong condition, but with early diagnosis and ongoing medical management, individuals can often live full lives. It is important for affected individuals and their families to understand the condition and engage with regular health checks to monitor for tumour development and progression.
Symptoms & clinical features
The symptoms of MEN2A typically arise from the tumours that develop in the endocrine glands. Medullary thyroid carcinoma (MTC) often presents as a lump or swelling in the neck, and in some cases, it can lead to symptoms like diarrhoea or flushing. Phaeochromocytomas, tumours of the adrenal glands, can cause episodes of high blood pressure, headaches, sweating, and a rapid heartbeat [PMID:33671216].
Primary hyperparathyroidism, affecting the parathyroid glands, may lead to elevated calcium levels in the blood. This can result in symptoms such as fatigue, increased thirst and urination, bone pain, and kidney stones [PMID:32057790]. The age at which these symptoms appear can vary significantly among individuals, even within the same family.
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Affected organs
MEN2A primarily affects three main endocrine glands: the thyroid gland, the adrenal glands, and the parathyroid glands. The thyroid gland, located in the neck, is where medullary thyroid carcinoma develops. The adrenal glands, situated on top of the kidneys, are the site of phaeochromocytomas.
The parathyroid glands, usually four small glands located behind the thyroid, can develop benign tumours (adenomas) or enlargement (hyperplasia) leading to primary hyperparathyroidism. Less commonly, other parts of the body might be affected, such as the nerves of the digestive system, which can be linked to certain bowel symptoms [PMID:32057790].
Risks & severity
Individuals with MEN2A have a very high lifetime risk of developing medullary thyroid carcinoma, approaching 100% if the thyroid gland is not removed proactively. The risk of developing phaeochromocytoma is significant, affecting about 50% of individuals with MEN2A. Primary hyperparathyroidism occurs in approximately 20-30% of affected individuals.
The severity of MEN2A can vary, even within the same family. Tumours can develop at different ages, from childhood into adulthood. Early detection through genetic testing and subsequent surveillance is crucial for effective management and can significantly improve long-term outcomes. The exact prevalence of MEN2A is not well established, but research suggests it affects approximately 1 in 35,000 individuals.
Genetic causes
MEN2A is caused by specific changes, known as pathogenic variants or mutations, in the RET gene. The RET gene provides instructions for making a protein called a receptor tyrosine kinase, which plays a vital role in cell signalling, growth, and development. This encoded protein is particularly important for ensuring proper formation of the nervous system, including nerve cells in the digestive tract, and also supports kidney function and spermatogenesis.
Pathogenic variants in RET in MEN2A typically lead to the receptor protein being constantly active, even in the absence of the usual signals [PMID:34208493]. This uncontrolled activity promotes abnormal cell growth and division, ultimately leading to the development of the characteristic tumours seen in MEN2A.
- RET ret proto-oncogeneThe RET gene provides instructions for a receptor tyrosine kinase protein involved in cell signalling, crucial for the development of various nerve cells, kidneys, and spermatogenesis.
Inheritance pattern
MEN2A is inherited in an autosomal dominant pattern. This means that a person only needs to inherit one copy of the altered RET gene from one parent to develop the condition. If a parent has MEN2A, there is a 50% chance with each pregnancy that their child will also inherit the pathogenic variant and therefore be at risk of developing the condition.
MEN2A can also occur spontaneously in an individual, meaning the pathogenic variant arises for the first time in them, with no family history. In such cases, the affected individual can then pass the condition on to their children. Genetic counselling is often recommended to help families understand the inheritance pattern and its implications.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
Diagnosis & testing
The diagnosis of MEN2A is typically confirmed through genetic testing, which looks for pathogenic variants in the RET gene. Genetic testing may be offered to individuals who present with one or more of the characteristic MEN2A-associated tumours, or to family members of someone already diagnosed with the condition. Clinical genetic services in the UK can facilitate this testing, which falls under NHS Genomic Medicine Service pathways.
Referrals for genetic testing and counselling are often made by endocrinologists, surgeons, or general practitioners. The relevant NHS R-code for germline RET testing for MEN2A would be associated with a clinical indication for inherited endocrine tumour syndromes. Family members may be offered predictive genetic testing to determine if they have inherited the causative variant, even before symptoms develop.
Management & lifestyle
Management for individuals with MEN2A focuses on early detection and treatment of tumours, as well as ongoing surveillance. For medullary thyroid carcinoma, prophylactic thyroidectomy (surgical removal of the thyroid gland) is often recommended in childhood, based on the specific RET pathogenic variant identified and associated risk level. Regular biochemical screening for calcitonin and carcinoembryonic antigen (CEA) levels can help monitor for MTC [PMID:33671216].
Surveillance for phaeochromocytoma typically involves regular blood and urine tests for metanephrines, alongside imaging such as MRI or CT scans. If a phaeochromocytoma is detected, surgical removal is usually recommended after appropriate medical preparation. Primary hyperparathyroidism is monitored through blood calcium and parathyroid hormone levels, and may require surgical removal of affected parathyroid glands. Management plans are individualised and often involve a multidisciplinary team including endocrinologists, surgeons, and geneticists, aligning with NHS care pathways.
UK care pathway
In the UK, individuals suspected of having or diagnosed with MEN2A are generally managed through the NHS Genomic Medicine Service. This involves referral to clinical genetics services for confirmation of diagnosis via germline genetic testing (e.g., under relevant R-codes for inherited endocrine tumour syndromes). Clinical geneticists and genetic counsellors provide essential information about the condition, its inheritance, and implications for family members.
Ongoing care and surveillance are typically coordinated by specialist endocrinology teams, working closely with surgeons, oncologists, and other specialists as needed. Genetic counsellors play a key role in supporting families, discussing screening protocols, and explaining reproductive options.
Frequently asked questions
What does 'autosomal dominant' inheritance mean for my family?
Autosomal dominant means that if you have MEN2A, each of your children has a 50% chance of inheriting the condition. This applies to each pregnancy, regardless of whether previous children have inherited it or not.
If I have MEN2A, will I definitely get all the associated tumours?
While the risk of developing tumours like medullary thyroid carcinoma is very high, not everyone with MEN2A develops all the associated tumours. The risk for phaeochromocytoma and hyperparathyroidism is significant but not 100%. Regular screening helps monitor for these.
What kind of regular check-ups will I need if I have MEN2A?
If you have MEN2A, you will typically need regular blood tests to check hormone levels related to your thyroid, adrenal, and parathyroid glands. Imaging scans may also be part of your surveillance programme to look for tumours, especially in your adrenal glands.
Can MEN2A be cured?
MEN2A is a lifelong genetic condition, but its effects can be managed very effectively. Early detection and surgical removal of tumours, especially the thyroid gland, can significantly reduce the risks and allow individuals to lead healthy lives. There is no 'cure' for the underlying genetic change.
Where can I find support for living with MEN2A in the UK?
In the UK, your clinical genetics team and specialist endocrinology service can provide comprehensive support and information. Patient organisations for endocrine conditions may also offer resources and peer support networks.
References
- Greenberg LA. Multiple Endocrine Neoplasia Type 1, Type 2A, and Type 2B. Primary care. 2024. PMID: 39067973
- Al-Salameh A, Haissaguerre M, Tresallet C. Syndromic primary hyperparathyroidism. Journal of visceral surgery. 2026. PMID: 42736063
- Macdonald JS. Parathyroid neoplasia. Current opinion in oncology. 1991. PMID: 1675125
- Bellet D. Tumor-susceptibility markers. Journal of the National Cancer Institute. Monographs. 1992. PMID: 1616794
- Giarelli E. Multiple endocrine neoplasia type 2a (MEN2a): a call for psycho-social research. Psycho-oncology. 2002. PMID: 11835593
- Yamashita S. Sporadic multiple endocrine neoplasia type 2A. Internal medicine (Tokyo, Japan). 1999. PMID: 10225659
- Li Y, Simonds WF. Endocrine neoplasms in familial syndromes of hyperparathyroidism. Endocrine-related cancer. 2016. PMID: 27207564
- Dunn JM, Farndon JR. Medullary thyroid carcinoma. The British journal of surgery. 1993. PMID: 8428296