There are five paraganglioma-pheochromocytoma syndromes associated with heterozygous germline mutations in genes encoding the subunits of the succinate dehydrogenase enzyme complex: PGL1–SDHD gene; PGL2–SDHAF2 gene; PGL3–SDHC gene; PGL4–SDHB gene; and PGL5–SDHA gene. The gene discussed is SDHD; the disease is pheochromocytoma.