Since the publication of the WHO CNS5 classification, the importance of molecular markers in the diagnosis, prognosis, and treatment planning has been emphasized: TERT promoter mutation, EGFR amplification, and chromosome +7/-10 copy number variation for IDH-wildtype glioma; CDKN2A/B homozygous deletion for IDH-mutant astrocytoma; H3K27 and H3G34 alteration for pediatric-type glioma (8); MGMT promoter methylation for the treatment response to temozolomide (21). The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).