As described above, IgG4 can also bind FcγRI and FcγRIIa, indicating a potential involvement of monocytes/macrophages in the pathogenesis of this subset of IBD with a high IgG4 level, inducing an IgG4-immune complex-FcγR signaling in the pathogenetic mechanisms. The gene discussed is FCGR2A; the disease is inflammatory bowel disease.