Molecular abnormalities in tumors associated with multiple endocrine neoplasia type 2.

The tumors of the MEN 2 syndromes, medullary thyroid carcinoma and pheochromocytoma, undergo defined stages of tumor progression. During these stages, several molecular abnormalities develop. These include abnormalities in growth, differentiation, and biochemistry. Recently, the germ-line abnormality in MEN 2A and familial medullary thyroid carcinoma has been identified in the ret gene. This article discusses possible molecular mechanisms for these abnormalities and attempts to place them in the context of the biology of the normal progenitor cells.