Strictly speaking, the new classification defines GBM as ‘glioblastoma, IDH-wildtype’ (CNS WHO grade 4), with either one of the following altered molecular diagnostic markers [34]: TERT promoter mutation (~80%), simultaneous gain of chromosome 7 and loss of heterozygosity of chromosome 10q (+7/—0) [35], amplification and rearrangement of receptor tyrosine kinases, most commonly affecting EGFR (~50%) [34,36]. Here, IDH1 is linked to glioblastoma.