NAD, a cofactor for critical biological processes such as electron transport and redox metabolism, is derived from biosynthesis (de novo pathway) and salvage pathways (using compounds containing a pyridine base).84 In IDH-mutated glioma, the de novo synthesis of NAD is largely compromised owing to epigenetic silencing of nicotinate phosphoribosyltransferase (NAPRT1). The gene discussed is IDH2; the disease is central nervous system cancer.