Multiple endocrine neoplasia type 1

Multiple endocrine neoplasia, type 1 (MEN1) is characterized primarily by several different types of endocrine tumors. People affected by MEN1 typically develop tumors of the parathyroid gland, the pituitary gland, and the pancreas, although other glands may be involved as well. These tumors are often "functional" and secrete excess hormones, which causes many of the different signs and symptoms of the condition. A variety of non-endocrine tumors are also found in MEN1, including lipomas (fatty tumors); and tumors of the skin or the central nervous system (brain and spinal cord).^[2][1]

Signs and symptoms of MEN1 vary and largely depend on which endocrine glands are affected:^[2]

• Parathyroid tumors are present in 90% of people with MEN1 by age 20-25 years and may cause fatigue, depression, weight loss, constipation, nausea, vomiting, dehydration, kidney stones, fragile bones, and hypertension.
• Pituitary tumors can lead to headaches, vision problems, nausea and vomiting. In women, menstrual periods may become irregular or stop completely. Men may have decreased fertility, diminished sexual desire, and/or erectile dysfunction.
• Stomach, bowel or pancreas (also called the gastro-entero-pancreatic, or GEP tract) tumors can cause high blood sugar, weight loss, glossitis, anemia, diarrhea, blood clots, and skin rash.
• Adrenal tumors can cause a variety of symptoms depending on the type of hormones they secrete, including high blood pressure, irregular heartbeat, panic attacks, headaches, diabetes, abdominal pain, weakness, excessive hair growth, and stretch marks.
• Carcinoid tumors (slow-growing tumors that usually begin in the lining of the lungs or the digestive tract can cause flushing of the face and upper chest; diarrhea; and trouble breathing.

The tumors that develop in MEN1 are often benign; however, in some cases, they can become malignant (cancerous). Gastrinomas (a specific type of GEP tract tumor) and carcinoid tumors are the most likely to advance to cancer.^[2]

Multiple endocrine neoplasia, type 1 (MEN1) is caused by mutations in the MEN1 gene. MEN1 is a tumor suppressor gene which means that it encodes a protein that helps keep cells from growing and dividing too rapidly or in an uncontrolled way. Changes (mutations) in MEN1 result in a defective protein that is unable to carry out its normal role. This leads to the development of the many different types of tumors found in MEN1.^[1][2]

Multiple endocrine neoplasia, type 1 (MEN1) is inherited in an autosomal dominant manner.^[2] This means that to be affected, a person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with MEN1 has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

Yes, genetic testing is available for MEN1, the gene known to cause multiple endocrine neoplasia, type 1 (MEN1).^[2] Carrier testing for at-risk relatives and prenatal testing are possible if the disease-causing mutation in the family is known.

The Genetic Testing Registry (GTR) is a centralized online resource for information about genetic tests. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

A diagnosis of multiple endocrine neoplasia, type 1 (MEN1) is based on the presence of two of the following endocrine tumors: parathyroid tumors; pituitary tumors; and/or stomach, bowel or pancreas (also called the gastro-entero-pancreatic, or GEP tract) tumors. People with only one of the tumors may also receive a diagnosis of MEN1 if they have other family members with the condition. Identification of a change (mutation) in the MEN1 gene can be used to confirm the diagnosis.^[2][3]

In addition to a complete physical exam and medical history, laboratory tests that evaluate the levels of certain hormones in the blood or urine are often used detect the different types of tumors found in MEN1. Imaging studies such as computed tomography (CT scan), magnetic resonance imaging (MRI scan), and/or endoscopic ultrasound may be recommended to confirm the location and size of the tumors. Some people may also need a biopsy of the tumor to confirm the diagnosis.^[2][3]

People with multiple endocrine neoplasia, type 1 (MEN1) are usually managed with regular screening to allow for early diagnosis and treatment of endocrine tumors. This screening begins in early childhood and continues for life.^[2]

Recommended screening includes specific types of imaging studies every 3-5 years:^[2]

• Head magnetic resonance imaging (MRI scan) begining at age 5.
• Abdominal computed tomography (CT scan) or abdominal MRI scan beginning at age 20.

Annual blood tests are also recommended, which evaluate the levels of certain substances that can be elevated if an MEN1-associated tumor is present:^[2]

• Prolactin concentrations, which can be used to screen for pituitary tumors, are measured beginning at age 5.
• Calcium concentrations, which can be used to screen for parathyroid tumors, are measured beginning at age 8.
• Gastrin concentrations, which can be used to screen for gastrinomas (a specific type of gastro-entero-pancreatic tract tumor) are measured beginning at age 20.

When a tumor is detected through screening, the best treatment options depend on many factors, including the size, location, and type of tumor; and whether or not the tumor is "functional" (releasing hormones). Many tumors are treated with surgery. If a tumor is functional, removal of the affected endocrine gland often resolves health problems that may be present as a result of elevated hormones. In some cases, functional tumors can be treated with medications that block the function or lower the levels of the overproduced hormone. Chemotherapy or radiation therapy may also be used to to shrink or destroy tumors.^[2][3]

The long-term outlook (prognosis) for people with multiple endocrine neoplasia, type 1 (MEN1) varies. Although improved understanding of the signs and symptoms found in MEN1 and early diagnosis and treatment of the characteristic endocrine tumors have improved the prognosis for some MEN1-associated health problems, people with MEN1 have a shortened life expectancy. This is largely due to the risk of some tumors found in MEN1 such as carcinoid tumors and certain types of gastro-entero-pancreatic (GEP) tract tumors (tumors of the stomach, bowel or pancreas) becoming malignant (cancerous).^[2][4]