Objective: To investigate the possible association of mannose-binding lectin (MBL) genotypes with the outcome of rheumatoid arthritis (RA).
Methods: MBL genotypes and plasma concentrations were retrospectively determined in 140 RA patients who were selected from a major cohort followed up prospectively for up to 32 years.
Results: MBL-insufficient patients (those with 2 defective structural MBL alleles or with 1 defective allele combined with a low-expression variant of the normal allele) had unfavorable outcomes. The relative risk of a severe radiographic outcome event (30% of maximum radiographic destruction, or an RE30) was 3.1 (95% confidence interval 1.8-5.1) in the MBL-insufficient group versus the MBL-competent group (P < 0.0001). An RE30 occurred in 50% of MBL-competent patients within 17 years, while such an event occurred 9 years earlier in MBL-insufficient patients (i.e., within 8 years) (P < 0.0001). During the first 15 years, there was a significant trend toward lower hemoglobin levels (P < 0.04), higher erythrocyte sedimentation rates (P < 0.02), and a higher number of swollen joints (P < 0.05) in the MBL-insufficient group.
Conclusion: MBL genotypes giving rise to MBL insufficiency are highly significant risk factors for fast progression of radiographic joint destruction.