Univariate Cox regression indicated that high expression levels of HDAC1, HDAC3, HDAC7 and HDAC9 were associated with poor OS of glioma, and elevated expression levels of HDAC4, HDAC5, HDAC6 and HDAC11 were associated with a favorable prognosis of glioma (Figure 2A). Here, HDAC9 is linked to central nervous system cancer.