Multiple Endocrine Neoplasia Type 1 is a genetic condition that increases the risk of developing tumors. Some of these tumors may develop in the endocrine system, which is made up of different glands in the body that produce hormones. Hormones are chemicals that are important for sending messages in the body. The endocrine glands include the parathyroid gland, pituitary gland, adrenal gland, pancreas, and others. Other tumors may develop in parts of the body that are not in the endocrine system (non-endocrine tumors).
The main types of endocrine tumors seen in people with Multiple Endocrine Neoplasia Type 1 are:
- Parathyroid gland tumors (tumors in the small parathyroid glands next to the thyroid gland in the neck)
- Pituitary gland tumors (tumors in the pea-size pituitary gland near the base of the brain)
- Stomach, intestine, or pancreas tumors (known as tumors of the “gastro-entero-pancreatic,” or GEP, tract)
- Adrenal gland tumors (tumors in the glands on top of each kidney)
- Carcinoid tumors (tumors of the cells that line the digestive system, lungs, or the thymus gland in the chest)
Non-endocrine tumors may include:
- Facial angiofibromas (acne-like bumps that form near the nose and mouth)
- Collagenomas (skin-colored bumps on the trunk, neck, and limbs)
- Lipomas (tumors made of fatty tissue that grow just under the skin)
- Meningiomas (tumors of the membranes that surround the brain and spinal cord)
- Ependymomas (tumors of the fluid-producing cells in the brain or spinal cord)
- Leiomyomas (smooth muscle tumors)
People with Multiple Endocrine Neoplasia Type 1 may develop tumors that are cancerous (the tumor cells can spread to other parts of the body) or non-cancerous (the tumor cells do not spread).
Multiple Endocrine Neoplasia Type 1 is caused by changes in a gene known as MEN1. Genes carry information telling cells in the body how to work. The MEN1 gene helps to control how and when cells grow and divide.
People without Multiple Endocrine Neoplasia Type 1 carry two working copies of the MEN1 gene in their cells. One copy of MEN1 is inherited from each parent. Cells from people with Multiple Endocrine Neoplasia Type 1 carry one working copy of MEN1 and one copy that is changed. This change causes the gene to not work right. It is called an MEN1 variant.
About 90% of (9 out of 10) children with Multiple Endocrine Neoplasia Type 1 inherit the MEN1 gene variant from a parent who also has the syndrome. The other 10% of children with the condition have developed a new MEN1 variant that did not come from a parent. These children have no history of the syndrome in their family. In these cases, the change either happened in an egg or sperm cell when the child was formed or in one of the child’s cells during pregnancy. These children are the first in their families to have Multiple Endocrine Neoplasia Type 1.
No matter how they acquired the MEN1 variant, people with Multiple Endocrine Neoplasia Type 1 have a 50% (1 in 2) chance of passing it on to their children.
As people with Multiple Endocrine Neoplasia Type 1 get older, the remaining working copy of MEN1 often becomes changed within some of their cells. When both copies of the gene are changed, tumors can develop. This is why people with Multiple Endocrine Neoplasia Type 1 have a higher risk of developing tumors than people who do not have the condition.
A doctor may suspect this diagnosis after looking at a person’s medical or family history. In most cases, a doctor or genetic counselor will ask questions about the person’s health and the health of other family members. Read more about genetic counseling and genetic testing.
Diagnosing this syndrome is usually done by sequencing the MEN1 gene to find variants (gene changes).
Genetic testing does not always find a variant that is responsible for the syndrome. A person can still have the syndrome even if no variants in MEN1 are found. There may be more undiscovered genes that play a role in the development of this syndrome.
Multiple Endocrine Neoplasia Type 1 can be diagnosed when a person develops any two of the following types of endocrine tumors:
- Parathyroid gland tumors
- Pituitary gland tumors
- Stomach, intestine, or pancreas tumors (GEP tract tumors)
Or a person who develops only one of the tumors listed above may be diagnosed with Multiple Endocrine Neoplasia Type 1 if he or she has other family members with Multiple Endocrine Neoplasia Type 1.
People with Multiple Endocrine Neoplasia Type 1 have an increased risk of developing endocrine and non-endocrine tumors. These tumors are often non-cancerous, but sometimes they are cancerous. Even non-cancerous tumors may need to be removed or treated because they may press on nearby organs or may produce very high levels of hormones in the body.
Nearly all people with Multiple Endocrine Neoplasia Type 1 develop some type of endocrine tumor over the course of their lifetime. The lifetime risks by subtype are estimated as follows:
Endocrine tumors
- Parathyroid gland tumors: 100%
- Pituitary gland tumors: 10-60%
- Stomach, intestine, or pancreas tumors (GEP tract tumors): 34-55%
- Adrenal gland tumors: 20-40%
- Carcinoid tumors: 10%
Non-endocrine tumors
- Facial angiofibromas: 88%
- Collagenomas: 72%
- Lipomas: 34%
- Meningiomas: 8%
- Ependymomas: 1%
- Leiomyomas: rare (risk not defined)
Sometimes, tumors that are non-cancerous undergo changes that make them act more like cancer. This is most likely to happen for carcinoid tumors or for stomach, intestine, or pancreas tumors (GEP tract tumors).
Cancer screening involves tests to check for cancer before symptoms occur. The goal is to find cancer at the earliest and most treatable stage. Guidelines for cancer screening are available online. Recommended screenings may change over time as doctors learn more about this syndrome, so these screening tests should be discussed with a health care provider who knows this syndrome well.
Other ideas to reduce the risk of cancer include:
- Eat a healthful diet with lots of fruits and vegetables
- Get regular exercise
- Avoid smoking or using tobacco products
- Avoid secondhand smoke
- Avoid excess sun exposure and always wear sunscreen, hat, and protective clothing when out in the sun
- Get medical attention for unusual or ongoing symptoms
Because of the medical concerns related to this syndrome, specialists in the following areas may need to assess a child with Multiple Endocrine Neoplasia Type 1:
- Endocrinology
- Dermatology
- Otolaryngology (Ear, nose, and throat specialist)
Resources about Multiple Endocrine Neoplasia Type 1:
- American Multiple Endocrine Neoplasia Support (https://www.amensupport.org/)
- Association for Multiple Endocrine Neoplasia Disorders (UK)(https://www.amend.org.uk/)
- Genetics Home Reference (https://ghr.nlm.nih.gov/condition/multiple-endocrine-neoplasia)
- National Organization for Rare Disorders (https://rarediseases.org/rare-diseases/multiple-endocrine-neoplasia-type-1/)
Other resources:
- Making Sense of Your Genes: A Guide to Genetic Counseling (www.ncbi.nlm.nih.gov/books/NBK115508/)
Adapted from educational materials developed by the St. Jude Children’s Research Hospital Cancer Predisposition Program