It is demonstrated that the reduced expression of IL-10 is coupled with an increase of STAT-3 and a reduction of SOCS3 mRNA, indicating an essential modulation of the immune response, with attenuation of anti-inflammatory and an increase of proinflammatory mediators. This modulation may be related to the increased prevalence and severity of periodontitis in individuals with DS. The gene discussed is STAT3; the disease is periodontitis.