Medullary thyroid carcinoma and lack of renal agenesis

A MEN2A family with two asymptomatic carriers affected by unilateral renal agenesis

Accumulating evidences suggest RET gene's involvement in development of the kidney in mice and humans. Although it is well known that RET mutation causes multiple endocrine neoplasia type 2A (MEN2A), thus far only 3 individuals have been reported to have MEN2A and renal agenesis/dysgenesis. We report a MEN2A family with RET mutation in which two asymptomatic carriers presented with unilateral renal agenesis. A 48-year-old woman underwent total thyroidectomy with regional lymph node dissection in our department for medullary thyroid carcinoma. She had earlier surgical treatment for a left adrenal pheochromocytoma at the age of 45. In the screening for MEN type 2 for her three sons, a CT scan for adrenal pheochromocytoma incidentally found unilateral renal agenesis in two of the sons, one of whom had suffered from Hirschsprung's disease (HSCR). They had contralateral kidneys exhibiting compensatory hypertrophy and normal renal function. Genetic analysis detected C618R RET mutation in the proband and her 3 sons, and no other mutations were found in RET as well as glial cell line-derived neurotrophic factor (GDNF). Our data lend support to the hypothesis that constitutive active RET mutation in MEN type 2 might partially impair RET function and thereby cause loss of function phenotype such as renal agenesis or HSCR.

Multiple endocrine neoplasia type 2A: an unusual clinical presentation and association with renal dysplasia

We report what we believe to be the first case of a patient with multiple endocrine neoplasia type 2A (MEN 2A) and renal dysplasia associated with an RET 634 mutation. The proband presented at the age of 29 with medullary thyroid carcinoma (MTC), bilateral pheochromocytomas, and primary hyperparathyroidism. Screening of family members identified the syndrome in his father. Both the proband and his father carry RET 634 germline mutation resulting in cysteine to arginine amino acid substitution. The proband had a left nephrectomy at the age of 10 years. Histologic examination of the resected kidney revealed severe dysplasia. His father had normal renal tract on ultrasonography. The proband's clinical presentation was unusual, and initially thought to be an atypical pneumonia. Surgical management after pharmacologic alpha- and beta-blockage consisted of bilateral adrenalectomy, total thyroidectomy, and subtotal parathyroidectomy as a single procedure.