Pheochromocytomas and paragangliomas are neural crest-derived tumors of the nervous system that are often inherited and genetically heterogeneous. Genetic screening is recommended for patients and their relatives, and can guide clinical decisions. However, a mutation is not found in all cases. The aims of this proposal are to: 1) to map gene(s) involved in pheochromocytoma, and 2) identify genotype-phenotype correlations in patients with pheochromocytoma/paraganglioma of various genetic origins.