IDH1 and glioma: In the previous studies of The Cancer Genome Atlas (TCGA), the gene expression of GBM were classified as four subtypes proneural, neural, classical and mesenchymal [28]; and the lower-grade gliomas were subdivided into three subtypes: IDH mutation and 1p/19q codeletion; IDH mutation and no 1p/19q codeletion; and IDH wild type using the data of multiple platforms [24].