Numerous studies have demonstrated a clear association between levels of IL-17 in both serum and synovial fluid and markers of inflammation, including rheumatoid factor (RF), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and the Disease Activity Score 28 (DAS-28) in patients with rheumatoid arthritis (RA) [33]. This evidence concerns the gene IL17A and rheumatoid arthritis.