A kindred of multiple endocrine neoplasia type 2B

We describe familial cases of multiple endocrine neoplasia (MEN) 2B: A 48-year-old man is the proband. He had pheochromocytoma, medullary thyroid carcinomas (MTCs), parathyroid hyperplasia, mucosal neuromas, eversion of eyelids and Marfanoid appearance, and then underwent adrenalectomy and total thyroidectomy. Family screening revealed that his two daughters (10 and 8 years old) had mucosal neuromas and increased serum calcitonin (CT). Both of them had MTCs but no pheochromocytoma, and their MTCs were surgically removed. The father and his children have been in favorable condition since the operations. Southern blot analysis with 33 polymorphic DNA probes was done in MTCs obtained from two daughters. An RBP3 (10q11.2) locus linked to a predisposing gene on chromosome 10 was uninformative in either patient because of constitutional homozygosity. Loss of heterozygosity at the MYCL1 locus on chromosome 1p32 was observed in MTC from the younger sister, but no loss of heterozygosity was recognized in other loci examined. Deletion of the 1p32 locus may play a role in the development of MEN 2B.