IDH1 and glioblastoma: Moreover, several reports identified mutations in CSF not found in tumor tissue, suggesting that liquid biopsy can capture intratumoral heterogeneity and subclonal dynamics missed in surgical specimens (7, 13, 69) These findings are aligned with current evidence on key molecular biomarkers in glioblastoma, including MGMT promoter methylation, IDH1/2 mutations, EGFR amplification, and TERT promoter mutations, which define distinct prognostic and therapeutic subgroups (70).