(MEN1) (mŭl'ti-pĕl en'dō-krin nē-ō-plā'zē-ă) Syndrome characterized by tumors of the pituitary gland, pancreatic islet cells, and parathyroid glands; may be associated with Zollinger-Ellison syndrome; autosomal dominant inheritance, caused by mutation in the MEN1 gene on chromosome 11q.