TLR7 and systemic lupus erythematosus: HLA gene variants such as HLA-DRB1, HLA-DR2, HLA-DR3, tumor necrosis factor alpha-induced protein 3 (TNFAIP3), signal transducer and activator of transcription 4 (STAT4), and toll-like receptor 7 (TLR7) have also been associated with a predisposition to SLE [42].