TERT and glioblastoma: TERT promoter (TERTp) mutations are collectively one of the biological and diagnostic markers for GBM.5–7 TERT is a reverse transcriptase catalytic subunit of telomerase that maintains telomere lengths.8 Telomere maintenance is essential for the unlimited proliferation of tumor cells and occurs in many cancer types via the reactivation of telomerase.9–11TERTp mutations lead to increased TERT expression and telomerase activation.12TERTp mutations are frequently observed in GBM.