Knowledge brings understanding and a database of all known mutations in the genes encoding SDHA, B, C, and D will, we believe, represent a valuable tool and resource for both clinicians involved in the treatment of paraganglioma and pheochromocytoma patients, clinical geneticists needing a overview of current knowledge, and geneticists and other researchers needing a solid foundation for further exploration of the genetic aspects of these tumor syndromes, SDH function, and SDHA related phenotypes. This evidence concerns the gene SDHB and hereditary pheochromocytoma-paraganglioma.