HLA-DRB1 and gestational diabetes: We combined the gene expression and gene promoter methylation to screen for genes those regulate abnormalities from the GDM-related KEGG pathway gene regulatory network, and further screened hub genes such as STAT1, HLA-DOA, and HLA-DMB, HLA-DQB1, HLA-DRB1, HLA-DMA, HLA-DRA, HLA-DPB1, IFNGR2, and EIF2AK2.