[Correlation of matrix metalloproteinase-9 polymorphisms with chronic periodontitis in Uygur adults]

Objective: To investigate the association between matrix metalloproteinase-9 (MMP-9) polymorphisms and chronic periodontitis in Uygur adults. Methods: A total of 196 patients with chronic periodontitis and 97 healthy controls were selected from 2 500 Uygur people. Buccal swab samples were taken, the genomic DNA was extracted and the genotype distribution and allele frequency of MMP-9 were determined by PCR-restriction fragment length polymorphism (PCR-RFLP). The distribution of genotypes, allele frequencies and risk factors were analyzed by chi-square test and multiple logistic regression. Results: Significant difference was found between healthy controls and the mild periodontitis and moderate to severe periodontitis in the MMP-9 1562C/T CC genotype expression (χ(2)=9.901, P=0.002; χ(2)=13.397, P< 0.001), and detectable rate of MMP-9 1562C/T CC genotype in the three groups was 31.3%(30/96), 53.5% (53/99), 27.8%(27/97), respectively. The detectable rate of CT genotype expression in the three groups were 65.6% (63/96), 45.5% (45/99), 69.1% (67/97) respectively and there was significant difference between healthy controls and mild periodontitis and between the mild periodontitis and moderate to severe periodontitis (χ(2)=8.025, P=0.005; χ(2)=11.159, P<0.001). There was also significant difference in allele frequency between healthy controls and mild periodontitis and between mild periodontitis and moderate to severe periodontitis (χ(2)=6.270, P=0.012; χ(2)=8.184, P=0.004). Logistic analysis showed that age under 35 years old was the protective factor of chronic periodontitis (OR=0.061, 95% CI=0.035-0.108, P<0.001) while the male and CT genotype were the risk factors of chronic periodontitis (OR=2.392, 95%CI=1.496-3.819, P<0.001; OR=1.280, 95%CI=0.794-2.067, P=0.031). Conclusions: The susceptibility to chronic periodontitis in Uygur adults in Moyu county of Xinjiang is related to the age and gender and polymorphism of MMP-9. The age over 35 years old, male and CT genotype may be the risk factors of chronic periodontitis in Uygur adults.