PADI4 and rheumatoid arthritis: Tumor necrosis factor (TNF) receptor-associated factor 1 C5 region, TNF-α-induced protein, CD40, C-C motif chemokine ligand 2, antisense noncoding RNA in the INK4 locus, and peptidyl arginine-deiminase 4 are some of the well-documented genetic factors linked to ACPA-seropositive RA [81].