Association between interleukin-6 gene promoter -572C/G polymorphism and the risk of sporadic Alzheimer's disease.

Inflammation is a key component of Alzheimer's disease (AD), and we have examined the effect of two polymorphisms (-174G/C and -572C/G) in the promoter of the inflammatory cytokine interleukin-6 (IL-6) gene on risk of AD in 318 AD patients. Significant differences in genotype and allele frequencies of -572C/G IL-6 promoter polymorphism were observed between AD patients and controls. The GG genotype was associated with a decreased risk of developing AD (OR 0.423, 95% CI 0.200-0.894). Similarly, logistic regression analysis revealed that G allele was a protective factor for AD (OR 0.732, 95% CI 0.567-0.945). For -174G/C variability, no C variability was found in all the subjects. The frequency of the IL-6 -174G/C promoter polymorphism is very low or no variability in Henan Han population. The -572C/G polymorphism of IL-6 gene promoter region is associated with AD, and G allele is an independent protective factor for AD.