IDH1 and oligodendroglioma: In 2016, Tirosh et al. [136] selected 4347 cells from 6 untreated grade II oligodendrogliomas (harboring IDH1 or IDH2 mutations) and analyzed them using scRNA-seq, and found that the cells with proliferative characteristics were highly enriched in a small number of undifferentiated rare subpopulations, suggesting that malignant proliferative cells within oligodendrogliomas could mainly originate from such a subgroup.