However, recent studies suggests that IL-17 producing Th17 cells play a crucial role in pathogenesis of various autoimmune diseases such as multiple sclerosis (MS) [5], rheumatoid arthritis (RA) [6], systemic lupus erythematosus (SLE) [7], psoriasis [8], and chronic inflammatory bowel disease [9]. This evidence concerns the gene IL17A and rheumatoid arthritis.