Likewise, patients with RA showed higher levels of IL‐6 and TNF‐α in sera, synovial tissues, and synovial fluids than those with non‐inflammatory arthritis (McInnes & Schett, 2007; Wood et al., 1992; Houssiau et al., 1988; Bozkurt et al., 2000). This evidence concerns the gene IL6 and rheumatoid arthritis.