An autosomal dominant tumor predisposition syndrome caused by pathogenic variants in the MEN1 gene, characterized by an increased risk of tumors of the parathyroid glands, pituitary gland, and foregut neuroendocrine tumors (most commonly pancreatic islet cells). The disease is multiple endocrine neoplasia type 1 (MONDO_0007540). Also known as: MEA type 1, MEA type I, MEN1, MEN1 multiple endocrine neoplasia, MEN1 syndrome, MEN1-related multiple endocrine neoplasia, Wermer syndrome, Wermer's syndrome.