Prevalence of composite Interleukin-1 genotype in South Africa

Objectives: Periodontitis is a bacterially induced chronic inflammatory disease that destroys the supporting tissues of the teeth. A specific pattern of interleukin-1 polymorphisms (known as the composite IL-1 genotype) has been found to influence the severity of chronic periodontitis in some ethnic groups.

The objective of this study was to evaluate the association between the IL-1 composite gene polymorphism and the severity of periodontal disease in a selected Xhosa population of South Africa.

Methods: Ninety-nine subjects, 35-60 years of age who were non-smokers and free of systemic disease were enrolled in a case-control study depending on their periodontal status (healthy to mild vs. moderate to severe disease). A buccal smear was obtained from each subject; the DNA was isolated then amplified using the polymerase chain reaction (PCR). Allele identification was either by real-time PCR or by size fractionation following restriction digestion and separation on a polyacrylamide gel.

Results: The prevalence of the composite genotype was 6% in the 99 subjects of the study population. The composite genotype occurred more frequently in cases (8.2%) than in controls (4%), but the difference was not significant (p=0.436). The frequency of IL-1A +4845 allele 2 was 47 % in cases and 22 % in controls (p= 0.009), and that for IL-1B +3954 was 14.3 % in cases and 20 % in controls (p=0.595).

Conclusions: This study demonstrated that the IL-1 composite polymorphism was not related to the severity of chronic periodontitis in the Xhosa population of South Africa.