IDH1 and glioblastoma: In this new classification, GBMs are divided in glioblastoma IDH-wildtype, 90% of cases, corresponding with what is defined as primary or de-novo glioblastoma, which predominates in patients over 55 years of age, glioblastoma IDH-mutant, about 10% of cases, which are closely related to the so-called secondary glioblastomas as are those with a history of prior lower grade diffuse gliomas preferentially occur in younger patient and glioblastoma NOS in tumors for which full IDH evaluation cannot be performed.