IRF5 and rheumatoid arthritis: Interestingly, IRF5 gene polymorphisms are linked to the development of various immune and inflammatory disorders including systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases, myeloperoxidase anti-neutrophil cytoplasmic antibody-associated vasculitis and asthma [21,22,23,24].