All pairs showed consistent IDH1/AbMole Tolclofos-methyl IDH2status.Correlation analysis with clinicopathological parameters revealed thatIDH1 mutation was not associated with malignant progression but was a potential prognostic marker for progressionfree survival and overall survival in astrocytomas. Watanabe et al. dissected multiple biopsies from the same patients and found that IDH1mutations always preceded acquisition ofTP53mutation or loss of 1p/19q.This genetic evidence suggests that IDH1mutations are early genetic events in the development of glioma from a cell-of-origin that can give rise to both astrocytes and oligodendrocytes. To date, little is known about the role of IDH1 and its clinical implications in the processes of glioma progression, particularly in Chinese patients. Previous reports were mainly focused on analysis of IDH1 status in primary gliomas or secondary gliomas. Thus, the significance of IDH1in paired gliomas, especially its role in predicting malignant progression, remains to be further defined. In our study,we investigated the IDH1 and IDH2 status of 53 pairs of primary and recurrent gliomas by direct sequencing and anti-IDH1-R132H immunohistochemistry. All of the primary gliomas showed consistent IDH1/IDH2 status as the corresponding recurrent gliomas, includingthe three cases of rare mutant. No association was observed between IDH1 mutation and malignant transformation. Together with the fact that IDH1 mutation is an early event in gliomagenesis, its constant statusthroughout the tumor evolution and absenceof association with malignant transformation suggest that IDH1 mutation is likely involved in tumor initiation instead of malignant progression. Interestingly, a very recent paper by Lass et al. showed that a small number of gliomas changed its IDH1 status in recurrence. Evidence has accumulated in the literature regarding the prognostic impact of IDH1 mutation in gliomas, particularly high grade gliomas. The prognostic significance of IDH1 mutation in LGG is more debatable. Dubbink et al. investigated the IDH1/IDH2 status in 49 low grade astrocytomas and demonstrated the association between IDH1 mutation and improved OS. In another study, Houllier et al. analysed the clinical and molecular data of 271 LGGs and identified IDH1/ IDH2 mutation as an independent prognostic marker in OS of LGG after adjusting for age, gender, Karnofsky performance status, histology, type of surgery, chromosome 1p/19q status and MGMT methylation. By studying 404 gliomas, Sanson et al. also showed the independent prognostic significance of IDH1 mutation in OS of gliomas by multivariate analysis adjusting for age, histological grade, type of surgery, postoperative treatment and molecular alterations.In a study investigating various molecular markers of 139 LGGs, Hartmann et al. found that IDH1 mutation was the strongest prognostic marker for OS regardless of histology.