Sandbox:ajay

Mutations in the MEN1 gene cause multiple endocrine neoplasia type 1. 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 rapidly 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 mutations inactivate both copies of the MEN1 gene, 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.

Multiple endocrine neoplasia type 1 usually has an autosomal dominant pattern of inheritance. People with this condition are born with one mutated copy of the MEN1 gene in each cell. In most cases, the altered gene is inherited from an affected parent. The remaining cases are a result of new mutations in the MEN1 gene and occur in people with no history of the disorder in their family.

Unlike most other autosomal dominant conditions, in which one altered copy of a gene in each cell is sufficient to cause the disorder, two copies of the MEN1 gene must be altered to trigger tumor formation in multiple endocrine neoplasia type 1. A mutation in the second copy of the MEN1 gene occurs in a small number of cells during a person's lifetime. Almost everyone who is born with one MEN1 mutation acquires a second mutation in certain cells, which can then divide in an unregulated way to form tumors.