From a more functional angle, never-smoking RA patients carrying the MBL-high genotype were less likely to be RF-positive (52%) as compared with patients carrying the MBL-low genotype (63%, OR 0.65, 95% CI 0.44 to 0.97), but no difference was observed in ever smokers (69% versus 70%). This evidence concerns the gene MBL2 and rheumatoid arthritis.