Genetic polymorphisms of the IL-1 alpha and IL-1 beta 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 for ms 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 purp ose 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 po pulation 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 PC R amplification, followed by restriction enzyme digestion and gel electroph oresis. The IL-1 alpha +4845 locus, in linkage disequilibrium (>99%) with I L-1 alpha -889, was genotyped because it is technically easier. Data were a nalyzed using r x c contingency tables. Results: The IL-1 beta +3953 allele "1" was carried by >99% of the AA contr ol 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 Af rican-American population, it would appear that knowledge of this +3953 pol ymorphism would provide little diagnostic or predictive information for LJP .