What are the genetic changes related to multiple endocrine neoplasia ?
Mutations in the MEN1, RET, and CDKN1B genes can cause multiple endocrine neoplasia.  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.  Mutations in the RET gene cause multiple endocrine neoplasia type 2. This gene provides instructions for producing a protein that is involved in signaling within cells. The RET protein triggers chemical reactions that instruct cells to respond to their environment, for example by dividing or maturing. Mutations in the RET gene overactivate the protein's signaling function, which can trigger cell growth and division in the absence of signals from outside the cell. This unchecked cell division can lead to the formation of tumors in endocrine glands and other tissues.  Mutations in the CDKN1B gene cause multiple endocrine neoplasia type 4. This gene provides instructions for making a protein called p27. Like the menin protein, p27 is a tumor suppressor that helps control the growth and division of cells. Mutations in the CDKN1B gene reduce the amount of functional p27, which allows cells to grow and divide unchecked. This unregulated cell division can lead to the development of tumors in endocrine glands and other tissues.