IDH1 and glioblastoma: Based on the aforementioned prognostic role of IDH mutations, the World Health Organization (WHO) recently suggested new classification of GBM into (1) IDH-wildtype or IDH negative GBM (about 90 % of cases) that preferentially arises in patients over 55 years of age and shows mostly poor prognosis; (2) IDH-mutant or IDH positive GBM (about 10% of cases) that predominates in younger patients and shows better prognosis [50,51].