Recent studies have indicated that the interleukin-12/interferon-g (IFN-g) axis is important in mycobacterial infection susceptibility. Using an intronic (CA) n polymorphic microsatellite marker within the IFN-g receptor-1 (IFNGR1) gene, we have compared the allelic frequencies of this marker in hospitalized tuberculosis patients (n ¼ 120) with that of controls (n ¼ 87) from Rijeka, Croatia. We identified 13 (CA) n alleles in the tuberculosis patients, whereas only 10 were found in the controls. A significant difference between one allelic marker and the control group was observed (P ¼ 0.02, 95% confidence interval 0.14-0.94), suggesting a possible protective association. In contrast, several other allelic markers showed a trend towards association with the disease. We also found a trend towards an increased frequency in homozygosity of one allelic marker in patients (11.7%) as compared with controls (4.6%). We conclude that there is no evidence for disease association of the IFNGR1 gene marker in Mendeliantype (single-allele) inheritance. However, our results also suggest that unidentified allelic variations in the IFNGR1 gene might elevate or decrease the risk in this ethnic population, as a part of the multigenic predisposition to tuberculosis.

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