IL17A and rheumatoid arthritis: In addition, the rs2275913, rs763780 and rs4819554 are all tag SNPs and most frequently studied among the enormous genes of IL-17A, IL-17F and IL-17RA, and previous studies indicated that these three SNPs are associated with diseases such as recurrent pregnancy loss (RPL), rheumatoid arthritis (RA), inflammatory bowel disease, and kidney disorders [13,15–17].