PADI4 and rheumatoid arthritis: Many loci from other genes outside the MHC region contribute to RA as well, such as tyrosine‐protein phosphatase nonreceptor type 22 (PTPN22)64 with an OR of about 1.7565 and peptidyl arginine deiminase 4 (PADI4)66 with an OR of 1.30 per risk allele.67