SDHD and pheochromocytoma: Familial HNPGLs together with pheochromocytomas (PCCs) account for about 40% and are associated with four types of hereditary paraganglioma syndromes (PGL1–5) caused by mutations in the following genes: SDHD (PGL1), SDHAF2 (PGL2), SDHC (PGL3), SDHB (PGL4), and SDHA (PGL5) (Burnichon et al., 2010; Boedeker et al., 2014).