HLA-DRB1 and rheumatoid arthritis: When combining the major genetic risk factor for RA (HLA-DRB1 SE) with anti-CPP3 IgG positivity, an increasing risk was observed for being pre-symptomatic (OR = 6.74; 95 % CI 1.43–31.81) compared with HLA-DRB1 SE-positive/anti-CPP3-negative individuals (OR = 3.55; 95 % CI 2.32–5.42), although no significant interaction between the two factors was found (Table 3).