Figure 3 Serum levels of mannan‐binding lectin (MBL) in the five multicase families with systemic lupus erythematosus (SLE) with low MBL. The patients with SLE have lower MBL levels than their first‐degree (1°) relatives, which in turn have lower levels than the second‐degree (2°) relatives. Distribution of MBL levels is compared using analysis of variance on ranks. Box plots show the median values and interquartiles, and the bars show the 10th centiles of MBL concentrations.