Consistent results have shown that peripheral blood neutrophils of people with chronic periodontitis (CP) or aggressive periodontitis (AgP) generate significantly more ROS upon simulation with purified immunoglobulin opsonized Staphylococcus aureus compared with peripheral blood neutrophils of healthy controls suggesting that people with periodontitis have a hyper-reactive phenotype of neutrophils and these neutrophils can be stimulated by the Fc-gamma receptor (FcγR) pathway (Gustafsson and Asman, 1996; Fredriksson et al., 1998; Gustafsson et al., 2006; Matthews et al., 2007a). The gene discussed is FCGR2A; the disease is periodontitis.