PTPN22 and systemic lupus erythematosus: Different risk alleles susceptibility loci, lupus-susceptibility genes, and SNPs have also been identified in SLE patients such as interferon regulatory factor (IRF5); HLA-DR2 and HLA-DR3, Ifi202 of Ifi200-family, PTPN22, CTLA4, STAT4 and BANK1, TLR 7, 8, 9, etc. (99–103).