tSNE dimensionality reduction of DNA methylation profiles from the 7 de novo RRD glioblastomas together with 1143 reference samples spanning 25 CNS tumor methylation groups and 3 control tissue methylation groups demonstrated two clusters of de novo RRD glioblastomas that were distinct from all established adult-type IDH-wildtype glioblastoma reference classes (Fig. 5a, Supplementary Table S7). Here, IDH1 is linked to glioblastoma.