HLA-DRA and central nervous system cancer: In addition, human leukocyte antigen (HLA) genes, including HLA-DPA1, HLA-DPB1, HLA-DQB1, HLA-DRA, HLA-DRB1 and HLA-G, took a large proportion of DEGs in either pathway 3 or 6, particularly in pathway 6, in which these genes were upregulated at grade IV, conforming to the significant expression of HLA-DQB1 and HLA-DRB1 in patients with high-grade glioma (HGG) observed by La Torre et al (22), and the positive correlation between HLA-DRB1 and symptomatic cerebral glioma reported by Guerini et al (23).