Familial pheochromocytoma and paraganglioma syndromes are autosomal-dominant disorders caused mostly by germline mutations in the succinate dehydrogenase subunit (SDH) genes, such as SDHB, SDHC, SDHD, SDHA, and SDHAF2 (succinate dehydrogenase complex assembly factor 2). The gene discussed is SDHB; the disease is pheochromocytoma.