What is multiple endocrine neoplasia type 1 (MEN 1)?

Related conditions:

Hyperparathyroidism, pituitary tumor, pancreatic tumor, duodenal tumor

Definition:
Multiple endocrine neoplasia type 1 (MEN 1) is a hereditary tumor syndrome characterized by endocrine and nonendocrine tumors, most of which are benign. The characteristic findings include tumors of the parathyroid glands, pituitary gland, pancreas, and duodenum (part of the small intestine). Neuroendocrine tumors (nerve-cell tumors that may produce hormones) in the pancreas and duodenum are the main cause of tumor-related death. The severity varies within families and between families.

Risk factors: Because MEN 1 is hereditary, the main risk factor is having a family history of this disorder. Each child of a person with MEN 1 has a 50 percent chance of inheriting the disorder.

Etiology and the disease process: The underlying genetic cause of MEN 1 is a mutation, or a genetic change, in the MEN1 gene. MEN1 is a tumor-suppressor gene, and the protein it encodes helps stop uncontrolled cell growth and proliferation.

Usually, each person has two normal copies of the MEN1 gene. A mutation in one copy of the gene is sufficient to cause MEN 1, which is why this condition is referred to as autosomal dominant (autosomal means the MEN1 gene is located on one of the twenty-two pairs of autosomes, which are the nonsex chromosomes). An affected person has a MEN1 gene mutation from the time of conception in the womb; however, symptoms of the disease may not manifest until later in life. Most mutations are inherited from a parent, but new mutations do occur.

Incidence: According to the US National Library of Medicine's Genetics Home Reference in 2014, approximately 1 per 30,000 people have MEN 1.

Symptoms: Parathyroid tumors can cause high calcium levels in the blood, nausea, fatigue, muscle pains, constipation, abdominal pain, kidney stones, and bone fractures. Symptoms of pituitary tumors vary depending on the type of hormone being made by the tumor. Tumors of the pancreas and duodenum cause many different symptoms depending on the tumor type.

Screening and diagnosis: Physicians diagnose MEN 1 in a person with an endocrine tumor in two of the three tissue systems usually affected in this syndrome: parathyroid glands, pancreas, and pituitary gland. Because MEN 1 is caused by mutations in the MEN1 gene, genetic testing can be used to confirm a suspected diagnosis or to test a family member who is at risk for the disease but has no symptoms.

Treatment and therapy: A combination of surgery and medication may be used to treat MEN 1 tumors.

Prognosis, prevention, and outcomes: Because MEN 1 is a genetic condition, its manifestations cannot currently be prevented. However, physicians recommend monitoring that includes blood testing for hormone levels and imaging of the head and abdomen.

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