It is noteworthy that we demonstrated that arthritis patients had low serum levels of MBL compared with healthy donors and that concentrations of MBL correlated negatively with the levels of amino-terminal propeptide of type I procollagen (PINP) and C-terminal telopeptide of type I collagen (β-CTX), serum markers for osteoclastic activity, in patients with arthritis. Here, MBL2 is linked to arthritic joint disease.