FH and pheochromocytoma: A well-established example in gliomas is isocitrate dehydrogenase (IDH) (Yan et al., 2009), which converts isocitrate to α-KG, mutations have also been found in succinate dehydrogenase (SDH) and fumarate hydratase (FH) in other conditions including phaeochromocytoma, paraganglioma, and renal cell carcinoma (Eng et al., 2003).