Racial differences in selected cytokine allelic and genotypic frequencies among healthy, pregnant women in North Carolina

Background: Genetic susceptibility to diseases is likely influenced by common DNA variants in the form of single nucleotide polymorphisms (SNPs). The value of SNPs for linkage and association mapping studies may depend on the distribution of SNP allele frequencies across populations. Objectives: To establish the SNP allelic frequencies among Caucasian and African American women for tumor necrosis factor (TNF)α, transforming growth factor (TGF)β1, interleukin-10 (IL10), interleukin-6 (IL6), and interferon (IFN)γ. Materials and methods: DNA was extracted from whole blood from 123 healthy, pregnant women. PCR-based genotyping was performed for the genes encoding TNFα (-308G/A), TGFβ1 (codon 10C/T, codon 25C/G), IL10 (-1082A/G, -819T/C, -592A/C), IL6 (-174C/G) and IFNγ (874T/A). Allele frequencies were determined by Hardy-Weinberg Equilibrium and Linkage Disequilibrium tests. Differences in the SNP allelic frequencies between Caucasians and African Americans were assessed by the χ² of Amitage trend test. Results: SNP allelic and genotypic frequencies for IL6 and IFNγ, but not for TNFα, TGFβ1, and IL10, differed significantly between the Caucasian and African American women. Conclusions: Recognition of racial differences in SNP allelic and genotypic frequencies for selected cytokines is important for designing and powering future linkage and association mapping studies investigating the role of cytokines in human disease.