IL-6 gene promoter polymorphisms in Korean generalized aggressive periodontitis patients

Purpose: The primary cause for developing periodontitis is Gram (-) bacteria but the host factors such as a genetic factor can contribute to the clinical severity. The IL-6 is one of the key regulators of the host response to microbial infection and bone resorption. The purpose of this study was to investigate the association of generalized aggressive periodontitis (GAP) with IL-6 gene promoter polymorphisms.

Methods: The study population consisted of 52 GAP patients and 30 periodontally healthy control subjects from the Dept. of Periodontics, Chonnam National University Hospital. Genomic DNA was obtained from buccal swab. The IL-6 promoter -597, -572 and -174 regions were genotyped using PCR, restriction enzyme digestion and gel electrophoresis. Comparison of allele and genotype frequencies for each polymorphism was done by Fisher's exact test or χ ² analysis.

Results: The genotype distribution in the GAP group was 30.8%, 40.4%, 28.8% for G/G, G/A and A/A genotypes of -597 and a statistically significant difference was found in the distribution between the GAP and control group. Allele 2 frequency and carrier rate of -597 were higher in the GAP group than the control. At the position of -572, the genotype distribution in the GAP group was 23.1%, 55.8% and 21.2% for C/C, C/G and G/G genotypes. In female subjects, the genotype distribution were significantly different between 2 groups (p<0.01). In male subjects, allele 2 frequency was significantly lower in the GAP group. The genotype distribution of -174 was 96.2%, 3.8% for G/G and G/C genotypes and the allele 2 frequency was very low in the GAP group (1.9%), whereas no allele 2 was detected in the control group.

Conclusion: Associations were found in IL-6 gene promoter (-597 and -572) polymorphisms and GAP.

(This study was supported by second stage Brain Korea 21 project for school of dentistry.)