A RET mutation with decreased penetrance in the family of a patient with a "sporadic" pheochromocytoma.

We present the case of a 38-yr-old man with a sporadic, multifocal pheochromocytoma and paraganglioma who was discovered to carry a Y791F germline mutation in exon 13 of the RET proto-oncogene. This mutation was found in his 65-yr-old mother and his 86-yr-old maternal grandmother. Neither of them had either biochemical evidence of pheochromocytoma or medullary thyroid carcinoma. The patient had a pro-phylactic thyroidectomy, which revealed mild C-cell hyperplasia. This case brings to discussion several issues: (1) the benefit of screening patients with apparently sporadic pheochromocytomas for genetic mutations; (2) the management of patients and families with "lower-risk" RET mutations; and (3) the possibility that lower-penetrance RET mutations may contribute to the list of causes of familial pheochromocytomas.