HLA alleles, particularly HLA-DRB1 shared epitope alleles, have been shown to dominate the genetic risk in RA, while other less predominant loci includes the non-HLA variants [13] and multiple single nucleotide polymorphisms (SNPs) such as VEGFA [14], RANKL[15], MMP1-3 [14] and PTPN22 [16]. The gene discussed is PTPN22; the disease is rheumatoid arthritis.