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The MEN1 gene: what it does and why it matters | CION Cancer Clinics
The MEN1 gene makes a protein called menin, which acts as a brake on cell growth in the hormone-making glands. An inherited fault in it causes multiple endocrine neoplasia type 1, where growths appear in the parathyroids, the pancreas and the pituitary. This page explains what the gene normally does, how a fault passes through a family, and why carriers are watched from childhood. At CION Cancer Clinics, our oncologists explain what a gene result means for you and your family, and plan the checks that follow.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What does the MEN1 gene actually do?
- Which glands does a faulty MEN1 gene affect?
- How does one faulty copy lead to growths in several glands?
- What do the words on an MEN1 report mean?
- How is inherited MEN1 different from a single gland tumour?
- What do families get wrong about the MEN1 gene?
- What can this page not tell you about MEN1?
- Common questions about the MEN1 gene
The short answer
What does the MEN1 gene actually do?
The MEN1 gene holds the instructions for a protein called menin. Menin works as a brake inside the cells of the hormone-making glands, stopping them from dividing when they should not. When one copy of the gene is faulty from birth, that brake is weaker in every gland, and small growths can appear in several of them over a lifetime.
Where the gene does most of its work
Menin is made in almost every cell, but losing it shows up mainly in the endocrine glands. These are the glands that release hormones into the blood: the parathyroids in the neck, the hormone cells of the pancreas and the pituitary at the base of the brain. That is why the condition is called multiple endocrine neoplasia type 1, or MEN1. Neoplasia simply means new growth.
Why it matters to the rest of the family
A fault in MEN1 is inherited in a dominant way. Each child of a carrier has a one in two chance of inheriting it, son or daughter alike. Once the exact fault is known, relatives can be tested for it directly, and those who do not carry it can stop worrying.
Most growths in MEN1 are benign. The harm usually comes from the extra hormone they release.Where growths appear
Which glands does a faulty MEN1 gene affect?
Doctors often call them the three Ps. Most carriers develop trouble in at least one, and many in more than one.
Parathyroid glands
Four rice-sized glands in the neck that control calcium in the blood. An overactive parathyroid is the most common sign of MEN1 and usually the first to appear.
Often noticed as
- Kidney stones at a young age
- High calcium on a routine blood test
- Tiredness or low mood with no clear cause
Pancreas and duodenum
Small growths called neuroendocrine tumours can form in the hormone cells of the pancreas and the first part of the small bowel. Some release too much gastrin, which drives stomach ulcers, or insulin, which drops blood sugar. These need the closest watch, because some can spread.
Pituitary gland
A pea-sized gland under the brain that steers many other glands. A growth here most often releases too much prolactin, which can stop periods, cause milk from the breasts or lower sex drive. A larger growth can press on the nerves to the eyes.
Other places
Less often, growths appear in the adrenal glands, the thymus in the chest, the lungs or the stomach lining. Harmless fatty lumps under the skin and small bumps on the face are also common, and can be a useful clue.
Not sure whether this applies to you?
Ask an oncologistFrom gene to growth
How does one faulty copy lead to growths in several glands?
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You carry two copies of MEN1
One came from each parent. One working copy is enough to keep menin doing its job, so a single faulty copy does no harm to a cell on its own.
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A carrier starts life with one working copy
In someone who inherits the fault, every cell already has one broken copy. The glands work normally, and there is nothing to see or feel.
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The second copy is lost in one gland cell
Over the years, the working copy can be damaged by chance in a single cell of a parathyroid, the pancreas or the pituitary. That cell now makes no working menin at all.
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That cell grows into a small tumour
Without the brake, the cell divides more than it should. Because the same thing can happen in many cells, carriers often have several small growths rather than one.
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Why no two carriers look the same
Which gland is hit first, and when, is largely chance. Two carriers in one family can have quite different histories, even with the identical fault.
On your report
What do the words on an MEN1 report mean?
- Menin
- The protein the MEN1 gene makes. It helps control when gland cells divide, repair themselves and switch other genes on or off.
- Tumour suppressor
- A gene whose job is to hold growth back. Losing both copies in a cell removes the brake, which is what happens in MEN1.
- Endocrine gland
- A gland that releases hormones straight into the blood, such as the parathyroid, the pituitary and parts of the pancreas.
- Neuroendocrine tumour
- A growth that starts in hormone-making cells. Many grow slowly, some release hormones, and a few can spread.
- Pathogenic variant
- A spelling change in the gene known to break it. Your report may also call this a mutation or a fault.
- De novo
- New in this person. The fault was not inherited from either parent, but it can still be passed to their children.
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Side by side
How is inherited MEN1 different from a single gland tumour?
Inherited MEN1
A one-off gland tumour
Growths in two or more glands, often over years
Usually one growth, in one gland
Often starts before middle age
More often found later in life
Several parathyroids tend to be involved
Usually a single enlarged parathyroid
Relatives can be tested for the exact fault
Relatives do not need a gene test
Lifelong checks, starting in childhood for carriers
Follow-up ends once the growth is treated
Commonly believed
What do families get wrong about the MEN1 gene?
"MEN1 is a type of cancer."
It is a tendency to grow tumours in hormone glands, and most of those tumours are benign. A minority, mainly in the pancreas and the thymus, can behave like cancer. That is exactly why carriers are checked regularly.
"Only the person with symptoms needs to think about it."
Every parent, brother, sister and child has a one in two chance of carrying the same fault. They can be tested for the family's exact fault, often long before any gland causes trouble.
"My parents are healthy, so I cannot have inherited it."
A parent can carry the fault with problems so mild they were never named, such as a kidney stone years ago. In a minority of people the fault is new, and neither parent carries it.
"Once the parathyroids are removed, the gene is fixed."
Surgery treats the growth causing trouble today. The gene fault sits in every cell and cannot be corrected or reversed, so the other glands still need watching for life.
Being straight with you
What can this page not tell you about MEN1?
It cannot tell you whether you or your child carries the fault. That is answered by a blood test for the exact fault already found in the family, arranged through a genetic counsellor or an endocrinologist. What your specific variant means is a question for the counsellor who ordered the test.
It cannot predict which gland comes next
Nobody can say which gland will be affected next, or when. That is the reason for a surveillance programme: regular blood tests and scans that look for trouble before it causes symptoms. The schedule is set by your specialist team, not by a web page.
Who this does not apply to
Most people with a single overactive parathyroid found in later life do not have MEN1, and do not need this test. The question is worth asking when growths appear young, in more than one gland, or in more than one relative. Some families who look like MEN1 test negative, and a different gene, CDKN1B, explains a small number of them.
Testing a tumour sample to choose a medicine is a different test. That lives under targeted therapy.Questions we are asked
Common questions about the MEN1 gene
Is MEN1 the same as having cancer?
No. MEN1 is an inherited tendency to grow tumours in hormone glands, and most of those tumours are benign. The problems usually come from extra hormones, such as high calcium. A smaller number of growths, mostly in the pancreas and the thymus, can turn cancerous, which regular checks are designed to catch.
How is MEN1 passed down a family?
It is dominant. A carrier has one faulty copy and one working copy, and passes one of the two to each child at random. So each child has a one in two chance of inheriting the fault. Sons and daughters are equally likely to inherit it.
Can MEN1 skip a generation?
The gene does not skip. A parent can carry the fault with such mild problems that nobody put a name to them, and then pass it to a child who becomes unwell. From the outside that can look like a missed generation, but the fault was there throughout.
How common is MEN1?
It is rare. MedlinePlus Genetics estimates about one person in thirty thousand. There is no reliable Indian figure, and many families are never diagnosed because each gland problem is treated separately by a different doctor, without anyone linking them together.
Does everyone with the fault become unwell?
Almost every carrier develops at least one gland problem by middle age, most often an overactive parathyroid. How serious it becomes varies a great deal. Many carriers live full lives with regular checks and treatment when a growth needs it.
Should my children be tested, and when?
MEN1 is one of the few conditions where testing in childhood is usually advised. Some pancreas and pituitary growths can appear before the teenage years, and checks can only start once a child is known to carry the fault. Your counsellor will suggest the right time.
Can MEN1 be treated with medicine instead of surgery?
Sometimes. Tablets can control a prolactin growth in the pituitary, and acid-lowering medicine can calm ulcers from too much gastrin. Other growths, such as overactive parathyroids, usually need an operation. The gene fault itself cannot be treated away.
Where do I start if MEN1 is suspected in my family?
Write down every gland problem, kidney stone and ulcer in the family, with rough ages. Take that list to an endocrinologist or a genetic counsellor. Call the CION helpline if you are unsure who to see, and we can arrange counselling in Telugu.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- GeneReviews (NCBI) — Multiple Endocrine Neoplasia Type 1
- MedlinePlus Genetics — MEN1 gene
- MedlinePlus Genetics — Multiple endocrine neoplasia
- National Cancer Institute — Genetics of Endocrine and Neuroendocrine Neoplasias (PDQ)
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
MEN1 and the parathyroid, pancreas and pituitaryWhat each gland problem feels like and how it is treatedMEN1 mutation: which cancers and what riskWhich growths can turn serious, and which rarely doTesting the family for MEN1Who should be tested once a fault is found, including childrenSurveillance for MEN1 carriersThe blood tests and scans carriers have, and why
Talk to us
Has someone in your family been told they have MEN1?
Tell us which glands were affected and at what age. We will help you find a genetic counsellor and work out who else in the family should be tested. One helpline serves every CION centre.