FCGR3B (Fc Fragment Of IgG Receptor IIIb) is a low affinity receptor for the Fc region of gamma immunoglobulins (IgG). The protein acts as a monomer and can bind either monomeric or aggregated IgG. This gene may function to capture immune complexes in the peripheral circulation. Diseases associated with FCGR3B include Neonatal Alloimmune Neutropenia and Eosinophilic Granulomatosis With Polyangiitis.