IDH1 and astrocytoma (excluding glioblastoma): In the present study, the frequency of IDH1/2 gene mutations in astrocytoma, anaplastic astrocytoma, primary glioblastoma and secondary glioblastoma was 82.5% (33/40), 27.3% (6/22), 17.3% (14/81) and 68.4% (13/19), respectively.