TERT and glioblastoma: Tumors with lower grades 2 and 3—which exhibit poor differentiation but lack necrosis and angiogenesis—are upgraded to GBM if any of three mutations are present: a gain-of-function-mutation in the EGFR promoter, the addition of chromosome 7 in conjunction with the absence of chromosome 10 (+7/−10), and/or the activation of TERT.