In multiple conditional logistic regression analysis with carriage of the PTPN22 1858T variant and HLA-SE as independent variables, both predicted RA but with the PTPN22 1858T variant giving the highest value (OR = 3.51, 95% CI 1.85–6.68 and OR = 2.19, 95% CI 1.22–3.94, respectively). Here, PTPN22 is linked to rheumatoid arthritis.