Values are the frequency in percent with absolute number of genotypes given in parentheses. Rheumatoid arthritis (RA) patients (n = 390) were stratified by rheumatoid factor (RF) status (values ≥40 IU/ml were regarded as RF positive (RF+)). RA patients for whom anti-cyclic citrullinated peptide (CCP) antibody concentrations were available (n = 258) were stratified according to anti-CCP positivity (values ≥50 IU/ml were regarded as CCP positive (CCP+)). The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated in the indicated patient subgroups in comparison to controls. Level of significance: ap = 0.001, power for all calculations α > 0.9.