Multiple endocrine neoplasia is a disorder that affects the body's network of hormone-producing glands called the endocrine system. Hormones are chemical messengers that travel through the bloodstream and regulate the function of cells and tissues throughout the body. Multiple endocrine neoplasia typically involves tumors (neoplasia) in at least two endocrine glands. However, tumors can also develop in other organs and tissues. These growths can be noncancerous (benign) or cancerous (malignant). If the tumors become cancerous, the condition can be life-threatening.
Many different types of tumors are associated with multiple endocrine neoplasia type 1 (MEN1). MEN1 frequently involves tumors of the parathyroid glands, the pituitary gland, and the pancreas. Tumors in these glands can lead to the overproduction of hormones. The most common sign of multiple endocrine neoplasia type 1 is overactivity of the parathyroid glands (hyperparathyroidism). Hyperparathyroidism disrupts the normal balance of calcium in the blood, which can lead to kidney stones, thinning of bones, nausea and vomiting, high blood pressure (hypertension), weakness, and fatigue.
MEN1 is caused by a mutation in the gene also called MEN1. This gene provides instructions for producing a protein called menin. Menin acts as a tumor suppressor, which means it normally keeps cells from growing and dividing too quickly or in an uncontrolled way. Although the exact function of menin is unknown, it is likely involved in cell functions such as copying and repairing DNA and regulating the activity of other genes. When the MEN1 gene is not working properly, menin is no longer available to control cell growth and division. The loss of functional menin allows cells to divide too frequently, leading to the formation of tumors characteristic of multiple endocrine neoplasia type 1. It is unclear why these tumors preferentially affect endocrine tissues.