Finally, we found that high HOTAIR expression is also associated with shorter overall survival in grade II (n = 226) and grade III (n = 240) glioma patients in the RNA-seq data from the larger TCGA dataset (Supplementary Tables 5 and 6; p = 0.020 and p < 0.0001, respectively; Log-rank test), and independently of patient age, gender, and molecular subtype (IDH and 1p/19q status) in the case of grade II gliomas (p = 0.032; Cox regression model), but not for grade III gliomas (p = 0.395; Cox regression model), in which high HOTAIR levels were highly correlated with wild-type IDH. Here, IDH1 is linked to glioma.