In sporadic pheochromocytomas, somatic mutations of VHL or RET are found in less than 10% of tumors, suggesting a possible role in tumorigenesis, whereas the prevalence and role of such mutations in hereditary pheochromocytomas such as those occurring in MEN 2 is not known. The gene discussed is RET; the disease is hereditary pheochromocytoma-paraganglioma.