Whereas little is known about the role of the SHBG locus (17p13) in determining RA progression, a number of experimental studies have shown that the FcγR3A locus (1q23) is involved in the recognition of IgG1 and IgG3 by NK cells and macrophages and that the activation of this receptor by IgG and IgG-RF immunocomplexes might lead to the initiation of a range of sustained and harmful inflammation events that, if chronified, may cause joint and bone destruction and promote the onset of RA72–74. This evidence concerns the gene FCGR3A and rheumatoid arthritis.