IDH2 and central nervous system cancer: Similar to what has been observed in AML patients, IDH1 and IDH2 gene mutations in gliomas are mutually exclusive, heterozygous, and restricted to the R132 site of IDH1 and the R172 site of IDH2. The discovery of IDH mutations in gliomas has allowed for further characterization of the sequence of events in glioma pathogenesis.