Abstract 39

Multiple endocrine neoplasia type 2A (MEN2A) is an autosomal dominant syndrome characterized by the presence of Medullar Thyroid Cancer (MTC, 100% of the affected patients), pheochromocytoma (50%) and parathyroid hyperplasia (20-30%). At early stage, the MTC is efficiently treated by total thyroidectomy. The more sensitive assay to detect MTC is the calcium plus pentagastrin provocative calcitonin test. It is known at present that point mutations in the ret-protooncogen that alter a extracellular domain of de RET protein are responsible for MEN2A. Calcium or calcium plus pentagastrin provocative calcitonin tests were performed in members of four MEN2A affected argentinean families for early detection of MTC. Exon 11 of the same patients were amplified by PCR and fragments generated by the restriction enzymes CfoI and RsaI were analyzed by polyacrylamide gel electrophoresis. Ten patients with altered calcitonin test presented mutations in exon 11. Mutations were also observed in four children (4, 8, 9 and 11 years old) with normal calcitonin test. These results confirm the usefulness of the DNA analysis for screening of families affected of MEN2A that will allow to treat the children before the onset of MTC.