These results are in keeping with the observation that the substitution of a phenylalanine in the F-variant for the valine at position 158 within the ligand binding domain of FcγRIIIA results in a lower binding affinity for IgG1, IgG3, and IgG4 and the observation that patients with non-Hodgkin's lymphoma homozygous for the F-158 allotype exhibit a lower response to treatment with the anti-CD20 monoclonal antibody rituximab than patients homozygous for V-158 allotype [20, 21]. The gene discussed is IGHG3; the disease is non-Hodgkin lymphoma.