CYP2E1 and central nervous system cancer: According to the median value, the CYP2E1 mRNA expression level was designated as “low expression” or “high expression.” In TCGA, the level of CYP2E1 decreased with increasing WHO grade (II–IV) of glioma and correlated with the clinical characteristics, including age, 1p19q.‐codeletion status, and IDH mutation status (Figure 2A–D).