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-1 beta) 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-1 alpha -889 and the IL-1 beta +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-1 alpha -889 and IL-1 beta +3953 was transmitted more frequently with the EOP phenotype. The purpose of the present study was to determine the prevalence of the IL-1 alpha and IL-1 beta genotype polymorphisms in an African-American (AA) control population and in 37 African-Americans with localized juvenile periodontitis (LJP). Methods: The IL-1 alpha +4845 and IL-1 beta +3953 loci were genotyped by PCR amplification, followed by restriction enzyme digestion and gel electrophoresis. The IL-1 alpha +4845 locus, in linkage disequilibrium (>99%) with IL-1 alpha -889, was genotyped because it is technically easier. Data were analyzed using r x c contingency tables. Results: The IL-1 beta +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-1 beta +3953 and IL-1 alpha +4845 loci was 14% (AA control group) and 8% (AA LJP group). Conclusions: Given the high frequency of the IL-1 beta 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.