FCGR2B and immunoglobulin G4-related sclerosing disease: In addition, a functional single nucleotide polymorphism (SNP) in the inhibitory FCGR2B was found to be associated with atopy and increased IgE production, suggesting that FCGR2B SNP may have a role in allergy and IgG4-RD via its effects on IgE production (83).