ATRX and glioblastoma: The molecular characteristics of WHO grade 4 tumors (glioblastomas) were reported as follows: IDH1 mutation was present in six out of 29 cases (20.7%), loss of ATRX expression was observed in 10 out of 29 cases (34.4%), and p53 mutation was detected in 25 out of 29 cases (86.2%).