FCGR3B and microscopic polyangiitis: In support of this notion is the finding that low copy number of FCGR3B (Fc fragment of IgG, low affinity IIIb, receptor (CD16b)), has been coupled to the systemic autoimmune diseases systemic lupus erythematosus (SLE), vasculitis, microscopic polyangiitis and Wegener's granulomatosis [12].