Increased functional activity of the MBL-MASP complex was correlated with the mannose-binding lectin serum level in both healthy controls (P < 0.0001, r = 0.8, Fig. 1D) and Crohn’s disease patients (P < 0.0001, r = 0.75, Fig. 1E), particularly when the mannose-binding lectin serum concentrations were >500 ng/mL. This evidence concerns the gene MASP1 and Crohn disease.