H2BC21 and systemic lupus erythematosus: Especially, there are 32 genes enriched in the systemic lupus erythematosus pathway, including eight genes in HLA-family (HLA-DMA, HLA-DMB, HLA-DOB, HLA-DQA2, HLA-DQA1, HLA-DRA, HLA-DRB1, HLA-DQB1), 20 genes in the four core histones (H2A(6): H2AC6, H2AC13, H2AC14, H2AC15, H2AC16, H2AC17; H2B(6): H2BC3, H2BC4, H2BC13, H2BC14, H2BC15, H2BC17; H3(4): H3C3, H3C10, H3C11, H3C12; H4(4): H4C3, H4C11, H4C12, H4C13), as well as four genes (C2, C4B, C4A, TNF).