Isocitrate Dehydrogenase 1 (IDH1) catalyzes the oxidative decarboxylation of isocitrate to alpha ‑ketoglutarate. There are two subclasses in the IDH family, one of them utilizing NADP+ as the electron acceptor and the other using NAD+ (1). The protein encoded by this gene is the NADP+-dependent isocitrate dehydrogenase found in the cytoplasm and peroxisomes. In peroxisomes, IDH1 generates the NADPH required for intraperoxisomal reduction reactions. Mutations of Arg132 of human IDH1 result in a reduced ability of the enzyme to convert isocitrate to alpha ‑ketoglutarate, but the enzyme acquires the ability to generate 2-hydroxyglutarate (2HG) from alpha ‑ketoglutarate (2). Elevated levels of the metabolite 2HG are associated with a high risk of malignant brain tumors. Arg132 mutations of IDH1 are common in high‑grade gliomas, but not in other types of tumors (3).
