Plenge et al. [3] studied 14 candidate genes and found significant associations between RA and PTPN22, CTLA4, and PADI4. Although many genes have shown suggestive connections with RA, only HLADRB1 and PTPN22 have been confirmed to increase the genetic risk of developing RA [4]. This evidence concerns the gene PTPN22 and rheumatoid arthritis.