Multiple endocrine neoplasia types 1 and 2 (MEN 1 and MEN 2) are autosomal dominant disorders characterized by hyperparathyroidism; pituitary and islet cell tumors (MEN 1); and medullary thyroid cancer, pheochromocytoma, and hyperparathyroidism (MEN 2). Although there are two different mechanisms of tumorigenesis, these syndromes share some characteristics. Tumors are multicentric, recurrence is common, and treatment is difficult, a lifetime commitment. The identification of genetic loci for the MEN syndromes has ushered in a new era of diagnosis and treatment. MEN 1 has been mapped to chromosome 11q13 and genetic diagnosis is possible by linkage approaches. The mapping of the MEN 2 gene to chromosome 10q11.2 and identification of c-ret protooncogene mutations causative for this disorder have revolutionized the clinical approach to treatment of gene carriers. Better understanding of pathogenesis and early identification of carriers will likely improve outcome.
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