IDH1 and glioblastoma: The methylation signatures were developed to distinguish LGG IDH mutant from LGG IDH WT, LGG IDH mutant with 1p/19q codeletion (oligodendroglioma) from LGG IDH mutant with intact 1p/19q loci (diffuse astrocytoma) and GBM IDH mutant (progressive GBM) from GBM IDH WT (de novo GBM).