The incidence of [[pituitary tumor]]s is increased in [[multiple endocrine adenomatosis]] or neoplasia (MEA or MEN) (especially type I: autosomal dominant inheritance with high penetrance, also involves pancreatic islet cell tumors (which may produce [[gastrin]] and hence [[Zollinger-Ellison syndrome]]) and parathyroids ([[hyperparathyroidism]]), and in which the pituitary tumors are usually nonsecretory).