PTPN22 and rheumatoid arthritis: Assuming a 1% RA prevalence, similar to that observed in the white North American general population, the results indicate that individuals with the protective genotype at all three loci (0SE for HLA-DRB1, CC genotype for PTPN22 and the AGT/AGT TRAF1 diplotype) have a substantially reduced predicted risk of RA (0.29% vs. 1%), whereas those individuals in the highest-risk category (HLA-2SE, TT or TC genotype at PTPN22, and the GCG/GCG TRAF1 diplotype), have an estimated RA risk of 13.06% – representing more than a 45-fold increase in risk (Table S3).