Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder caused by MEN1 gene mutations, typically involving primary hyperparathyroidism (PHPT), pancreatic neuroendocrine tumors (PanNETs), and/or pituitary neuroendocrine tumors (PitNETs). The gene discussed is MEN1; the disease is multiple endocrine neoplasia type 1.