This gene encodes a receptor for the Fc portion of immunoglobulin G, and it is involved in the removal of antigen-antibody complexes from the circulation, as well as other responses, including antibody dependent cellular mediated cytotoxicity and antibody dependent enhancement of virus infections. This gene (FCGR3A) is highly similar to another nearby gene (FCGR3B) located on chromosome 1. The receptor encoded by this gene is expressed on natural killer (NK) cells as an integral membrane glycoprotein anchored through a transmembrane peptide, whereas FCGR3B is expressed on polymorphonuclear neutrophils (PMN) where the receptor is anchored through a phosphatidylinositol (PI) linkage. Mutations in this gene are associated with immunodeficiency 20, and have been linked to susceptibility to recurrent viral infections, susceptibility to systemic lupus erythematosus, and alloimmune neonatal neutropenia. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. CD16 (FcγRIII) is a low affinity Fc receptor that binds to IgG antibodies. Two forms of the receptor, CD16A (FcγRIIIa) and CD16B (FcγRIIIb) are present in natural killer cells, neutrophils, monocytes and activated macrophages. Antibody-dependent cell-mediated cytotoxicity (ADCC), cytokine release and microbe killing can be induced upon binding with CD16. Sconocchia, et al. demonstrated in a recent study that colorectal carcinoma patients with high CD16+ cell infiltration was associated with improved overall survival after adjusting for known prognostic factors and this association was independent from CD8+ lymphocyte infiltration and presence of metastases.