A family of multiple endocrine neoplasia type 2A (MEN 2A) with Cys630Tyr RET germline mutation: report of a case.

Since the majority of multiple endocrine neoplasia type 2A (MEN 2A) patients have missense mutations at codon 634 and those with the Cys630 RET genotype mutations are extremely rare, limited clinical information is available about this rare type. We report here three members of one Japanese MEN 2A family with the Cys630Tyr genotype. A 67-year-old woman presented a firm thyroid nodule, and preoperative examination revealed medullary thyroid carcinoma with primary hyperparthyoidism and no pheochromocytoma. At surgery, bilateral medullary thyroid carcinomas and parathyroid adenoma were found. No lymph node metastasis was identified. Computed tomography scans and laboratory examination of blood have shown no evidence of tumor recurrence and no abnormality of parathyroid function during the 4 years after surgery. A 40-year-old man, the proband's son, was shown to have the same RET mutation, underwent total thyroidectomy prophylactically, and only microscopic foci of medullary thyroid carcinoma were found. A 10-year-old boy, the proband's grandson also having the same RET mutation, showed normal basal serum calcitonin level and has been followed up conservatively. To our knowledge, 18 patients of 6 families with the Cys630 mutations have been reported so far. This is only the second reported case with primary hyperparathyroidism. RET 630 mutations might be associated with lower penetrance of primary hyperparthyoidism and pheochromocytoma.