TERT mutations present in the vast majority of oligodendroglioma and IDH wildtype glioblastoma are mutually exclusive with ATRX mutations and alternative lengthening of telomerase seen in astrocytoma (Cancer Genome Atlas Research Network, 2015; Eckel-Passow et al., 2015). This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).