A group of autosomal dominant diseases characterized by the combined occurrence of tumors involving two or more endocrine glands that secrete peptide hormones or amines. These neoplasias are often benign but can be malignant. They are classified by the endocrine glands involved and the degree of aggressiveness. The two major forms are MEN1 and MEN2 with gene mutations on CHROMOSOME 11 and CHROMOSOME 10, respectively.