IDH1,also named as PICD and IDP,belongs to the isocitrate and isopropylmalate dehydrogenases family. It is a common feature of a major subset of primary human brain cancers. It can form a homodimer.IDH1 mutation is always heterozygotic and IDH1 functions as a dimer,theoretically there will be 25% each wild type and mutant homo-dimers and 50% hetero-dimers present in the tumor cells.