REVIEW Pheochromocytoma: The Expanding Genetic Differential Diagnosis

Pheochromocytomas and paragangliomas are tumors of the autonomic nervous system; pheochromocytomas are tumors of the adrenal medulla, and paragangliomas are extra-adrenal tumors arising from either the sympathetic nervous system or parasympathetic ganglia. It has previously been estimated that approximately 10%–15 % of pheochromocy-tomas are due to hereditary causes. However, our increased understanding of the three hereditary syndromes (neurofi-bromatosis 1, multiple endocrine neoplasia type 2, and von Hippel–Lindau syndrome) in which pheochromocytoma is found and the recent discovery that mutations in genes in the succinate dehydrogenase family (SDHB and SDHD) predis-pose to pheochromocytoma have necessitated a re-evaluation of the genetic basis of pheochromocytoma. These studies in-dicate that the frequency of germline mutations associate