Multiple endocrine neoplasia type 1 (MEN1) is a genetic condition that causes tumors to form in endocrine glands and other organs. Despite not usually being cancerous, these tumors can be very aggressive.

MEN1 arises from genetic mutations in the MEN1 gene. Parents with these mutations can pass them on to their offspring.

This article takes a detailed look at MEN1. After listing its symptoms, it will discuss MEN1’s causes and risk factors.

The article will then describe the diagnosis, treatment, and outlook of MEN1.

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According to the National Institutes of Health (NIH), MEN1 is a genetic disorder that affects the endocrine glands.

These glands have locations all over the body and create hormones that regulate the following bodily processes:

  • digestion
  • growth
  • sexual functions

MEN1 causes tumors to develop in some endocrine glands. These tumors are not usually cancerous, although they can still interfere with how endocrine glands function and adversely impact an individual’s overall health.

Some common locations of MEN1 tumors include:

Sometimes, MEN1 causes tumors to develop in other endocrine glands and even in the skin.

As the Genetic and Rare Diseases Information Centre explains, MEN1 can cause several possible symptoms.

Some very common symptoms of MEN1 include:

  • primary hyperthyroidism (when a parathyroid gland produces too much hormone)
  • enlarged parathyroid glands
  • difficulties with everyday activities, such as eating, dressing, and working

Some common symptoms of MEN1 include:

Less commonly, MEN1 can lead to vomiting, a shorter attention span, and nausea.

According to the National Organization for Rare Disorders, MEN1 is a genetic condition.

It arises from mutations of the MEN1 gene. In its healthy state, this gene functions to reduce tumor growth. It does this by telling cells when to die, stopping cells from dividing, or repairing DNA.

However, in people with MEN1, the MEN1 gene cannot perform this function as well as it should.

People can develop these genetic mutations during their lives. They can also inherit them from a parent who has the mutation.

For each pregnancy, the chance of an affected parent passing on these MEN1 gene mutations to their children is roughly 50%.

Risk factors for MEN1 are not necessarily the causes of this condition. However, they are things that indicate a higher chance of developing MEN1.

Given the heritability of MEN1, having a family member with this condition is a risk factor.

Furthermore, although MEN1 can affect people of all ages, the NIH states that most MEN1 diagnoses occur between the ages of 40 and 50 years.

As the NIH also explains, there are three criteria for a MEN1 diagnosis.

If an individual meets any of the following conditions, doctors may diagnose them as having MEN1:

  • having at least two MEN1-related tumors
  • having at least one MEN1-related tumor, plus having a first-degree relative who has MEN1
  • having a MEN1 genetic mutation

Doctors can check for MEN1 mutations by using genetic testing. This involves taking a blood or saliva sample and testing it in a laboratory.

Doctors may recommend genetic testing to people who have symptoms of MEN1. They may also recommend it to individuals with a family history of this condition.

The NIH details the treatment options for MEN1. This condition has no known cure. Treatment focuses on monitoring tumors and addressing the symptoms they may cause.

Doctors can monitor MEN1 tumor growth with blood tests and imaging tests. If the tumors require treatment, the details will depend on the tumor location.

Treatments include:

  • Parathyroid tumor treatment: Doctors can remove affected parathyroid glands with surgery. If this is not an option, they can prescribe medications that regulate calcium levels. This is because parathyroid gland tumors can lead to excess calcium in the blood.
  • Pancreas and digestive tract tumor treatment: Doctors can prescribe medications to manage symptoms, such as having too much stomach acid. They may also surgically remove the tumors and freeze or burn any liver tumors. In very rare cases, doctors may use chemotherapy, even for noncancerous MEN1 tumors.
  • Pituitary gland tumor treatment: Doctors can use medications or surgery to remove these tumors. Sometimes, they may also recommend radiation therapy.

In some cases, MEN1 only causes small and asymptomatic tumors. These do not require treatment.

According to a 2023 review, MEN1 tumors can be more aggressive than other tumors.

They can also be more prone to recurring. For these reasons, treating MEN1 can be challenging. People with MEN1 have a below-average life expectancy and an increased risk of premature death.

Some people who have MEN1 will develop cancerous tumors. Depending on their size and location, these can worsen the outlook for people with MEN1.

However, research has shown that not smoking reduces the risk of developing these tumors.

MEN1 is a genetic condition that arises from mutations in the MEN1 gene.

Parents have a high chance of passing on this gene mutation to their children. However, some people can develop MEN1 despite having no family history of the disease.

Since the MEN1 gene acts to suppress tumor growth, MEN1 causes tumors to form in various body parts. These include endocrine glands, the pancreas, and the digestive tract.

Because these tumors can affect so many organs, MEN1 may manifest in many different symptoms.

Doctors can treat MEN1-related tumors with surgery and medications.

Less rarely, they may also use chemotherapy and radiation therapy, which are common cancer treatments. Although MEN1 tumors are usually not cancerous, this can sometimes be the case.