Polymorphisms in an interferon-gamma receptor-1 gene marker and susceptibility to periodontitis.

Chronic marginal periodontitis is an inflammatory condition in which the supporting tissues of the teeth are destroyed. Interferon (IFN)-gamma is a cytokine that plays a pivotal role in the defense against infection, and mutations in the gene coding for the ligand binding chain (alpha, R1) of the IFN-gamma receptor (IFNGR1) confer suseptibility on infections caused by poorly virulent mycobacteria. Using an intronic (CA)n polymorphic microsatellite marker within the IFNGR1 gene we investigated whether genetic polymorphisms are associated with periodontitis. In 62 periodontitis patients and 56 healthy controls we found a total of 13 polymorphisms, 11 of which were found in the periodontitis patients and 9 in the controls. Although we observed a trend towards an association with disease for allele 192, there were no significant differences in allele frequency between patients and controls. We therefore cannot find any evidence to suggest that IFNGR1, as a single dominant gene, contributes to susceptibility to periodontitis. However, in combination with the environmental risk factor, smoking, the same allelic marker was significantly associated [OR = 5.56 (1.16<OR<36.31), P=0.014, Pcorr=0.027] with periodontitis. Our results support the multigene-environment interaction model of disease susceptibility to periodontitis.