IDH1 and glioblastoma: For instance, IDH-mutant astrocytomas with CDKN2A/B homozygous deletion are now graded as high-grade astrocytomas (grade 4), and IDH-wildtype diffuse astrocytomas with TERT promoter mutation, EGFR amplification, or + 7/−10 copy number changes, can now be classified as molecular glioblastoma, even if their histological appearance suggests a lower grade.