Genetic Polymorphisms of the IL‐1α and IL‐1β Genes in African‐American LJP Patients and an African‐American Control Population

Background: A functional polymorphism of the interleukin‐1 beta (IL‐1β) gene has been proposed to be a risk factor for periodontitis. In adult forms of periodontitis, non‐smokers of northern European heritage carrying the “2” allele of the IL‐1α‐889 and the IL‐1β +3953 RFLPs in either the heterozygous or the homozyous state at both loci were observed to have a greater risk for developing severe periodontitis. Studies of early‐onset periodontitis (EOP) found that allele “1” of both IL‐1alpha;‐889 and IL‐1β +3953 was transmitted more frequently with the EOP phenotype. The purpose of the present study was to determine the prevalence of the IL‐1α and IL‐1β genotype polymorphisms in an African‐American (AA) control population and in 37 African‐Americans with localized juvenile periodontitis (LJP). Methods: The IL‐1α +4845 and IL‐1β +3953 loci were genotyped by PCR amplification, followed by restriction enzyme digestion and gel electrophoresis. The IL‐1α +4845 locus, in linkage disequilibrium (>99%) with IL‐1α‐889, was genotyped because it is technically easier. Data were analyzed using r × c contingency tables. Results: The IL‐1β +3953 allele “1” was carried by >99% of the AA control population and by 100% of the AA LJP group, with most individuals being homozygous 1,1. The prevalence of the composite genotype with at least one allele “2” at each of the IL‐1β +3953 and IL‐1α +4845 loci was 14% (AA control group) and 8% (AA LJP group). Conclusions: Given the high frequency of the IL‐1β allele “1” in the African‐American population, it would appear that knowledge of this +3953 polymorphism would provide little diagnostic or predictive information for LJP. J Periodontol 2000;71:723‐728.

Aggressive periodontitis · Allele · Allele frequency · Biology · Cytokine · Gene · Genotype · Haplotype · Interleukin · Linkage Disequilibrium · Locus (genetics) · Periodontitis · Population · Restriction fragment length polymorphism · Gastroenterology · Genetics · Immune Response and Inflammation · Immunology · Internal Medicine · Medicine · Oral microbiology and periodontitis research · Streptococcal Infections and Treatments