Type 1 - Multiple Endocrine Neoplasia syndrome (MEN1,) is an autosomal dominant disorder secondary to MEN1 mutations that predisposes carriers to endocrine tumors. The MEN1 gene located on chromosome 11q13 encodes menin, a 610 amino acid protein expressed in all tissues tested. Menin is a scaffold protein which interacts with a large number of intracellular molecules. MEN1 disease may display various clinical associations The tumors mainly develop from endocrine tissues and may arise from parathyroid glands, duodeno-pancreas, pituitary gland, adrenal glands, and at a lower frequency from the bronchi and thymus. The penetrance is very progressive but ultimately high during a lifespan.