[The relationship between a nucleotide substitution of S100A8 gene and aggressive periodontitis]

To screen polymorphisms in the upstream region of S100A8 gene and to detect whether the polymorphisms were associated with aggressive periodontitis.

Thirty aggressive periodontitis patients and twenty-eight healthy controls were recruited for the study with informed consent. All subjects were of Chinese descent and systemically healthy. The regions about 800 bp upstream from the ATG start codon in exon 2 of the S100A8 gene of 10 patients and 8 controls were amplified by polymerase chain reaction (PCR) and analyzed by direct sequencing. A single nucleotide polymorphism (SNP) at 94 bp upstream from the ATG start codon was selected, and then the shorter regions (about 250 bp upstream from the ATG start codon) of the rest subjects were also amplified by PCR and analyzed by direct sequencing. The frequency of the SNP and the distribution of the genotype were detected and compared between the two groups.

A nucleotide substitution (A-->G) at 94 bp upstream from the ATG start codon was demonstrated in Chinese, which was in a cis-acting element, named gamma interferon response element (gamma-IRE) in intron 1 of S100A8 gene. All of the subjects that carried the polymorphism were heterozygous. There was no statistically significant difference in the frequency of allele 2 (corresponding to the nucleotide G) between patients and controls (11.7% vs. 17.9%, chi2 = 0.887, P > 0.05). The prevalence of the heterozygous genotype was 23.2% and 35.7% (chi2 = 1.07, P > 0.05) in patients and controls, respectively.

This is the first report that a nucleotide substitution of S100A8 gene was demonstrated in Chinese. The frequencies of allele 2 and heterozygous genotype were lower in patients, but there is no statistically significant difference between the aggressive periodontitis patients and healthy controls in this preliminary study.