Haplotype analysis on association between variants of interleukin 6 (IL-6) and late-onset Alzheimer's disease in a Chinese Han population.

Abstract

The aim of this study was to evaluate the influence of single nucleotide polymorphisms (SNPs) in interleukin-6 (IL-6) gene and the haplotype on late-onset Alzheimer's disease (LOAD). A total of 896 participants were enrolled, including 446 LOAD patients and 450 controls. Total genomic DNA was extracted from the blood of participants and genotyping was then performed. Hardy-Weinberg equilibrium test was conducted in controls. Multivariate analysis was performed to determine the association between 4 SNPs (rs1800796, rs7802308, rs1800795 and rs13447446) in IL-6 gene and LOAD. Pairwise LD analysis was employed to identify the association between haplotype and LOAD. Multivariate logistic analysis showed that T allele of rs7802308 and G allele of rs1800796 were correlated with decreased risk of LOAD, adjusted ORs were 0.68 (95% CI: 0.50-0.91) and 0.71 (95% CI: 0.51-0.92), respectively. However, rs1800795 and rs13447446 were not associated with LOAD. Pairwise LD analysis among the 4 SNPs showed that only rs1800796 and rs1800795 in IL-6 gene was in heavy LD, the D' value was >0.75 (0.825). In all samples, the haplotype C-G was observed most frequently in two groups, with 55.79% and 49.46% in the LOAD patients and controls, respectively. The results also indicated that haplotype G-C was significantly associated with decreased LOAG risk. T allele of rs7802308 and G allele of rs1800796 were correlated with decreased risk of LOAD. The haplotype G-C were also correlated with decreased risk of LOAD.