The defining characteristics of the PN subtype are also frequently found in lower-grade gliomas or secondary GBMs [42]–[44], and mutations in IDH1 and TP53 are normally found in 70% and 50 to 60%, respectively, of lower-grade astrocytomas [43], [45]–[47]. This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).