TERT and glioblastoma: Primary glioblastomas had the highest frequency of TERT promoter mutations (25/28; 89.2%, p=0.006) followed by oligodendrogliomas (29/35; 82.8%, p<0.001), while astrocytomas showed the lowest frequency, with 3 out of 15 (20%, p=0.107) samples showing mutations (Table 2). TERT promoter mutations were found to be associated with high grade (grade III/IV) tumors when compared to lower grade (grade II) lesions (p<0.033), and were more frequent in patients older than 55 years of age (p=0.023).