TERT and glioblastoma: For the secondary type of GBM, the most frequent genetic abnormality is the IDH mutation (60–80% of cases) which interferes with the metabolism, while the least frequent is PTEN loss (4%) which interferes with PIK3 signaling; For the primary type of GBM, the most frequent genetic abnormality is the TERT promoter mutation (60–80% of cases) which interferes with the telomere maintenance, while the least frequent is FGFR3-TACC3 fusion (3%) which interferes with RTK signaling [8,23,24,25,26,27,28].