A higher frequency of low FCGR3B CN (< 2) was observed in the RA patients compared with controls (13.7% and 6.2%, respectively), with OR 2.5 (95% confidence interval 1.2 to 5.4, P = 0.017) indicating an increased susceptibility for RA being associated with a low CN. This evidence concerns the gene FCGR3B and rheumatoid arthritis.