An interleukin-6 promoter variant is not associated with an increased risk for Alzheimer's disease

Recent studies have implicated interleukin-6 (IL-6) in the pathogenesis of Alzheimer's disease (AD). Neuro-inflammatory processes surrounding the amyloid plaques contribute to the progression of AD-related neurodegeneration. IL-6 is a multifunctional inflammatory cytokine which possibly acts as a mediator in the local immune response in the brain of AD patients. In this study we investigated whether the risk of developing AD is altered in carriers of the C allele of a G/C polymorphism at position -174. 113 AD patients and 108 age- and gender-matched nondemented control subjects were analysed. Genotyping of IL-6 was performed using standard PCR and restriction fragment length polymorphism methods. The results were adjusted for age, gender and apolipoprotein E epsilon4 status. There was no evidence for an association between the polymorphism and the risk of developing AD. No evidence of an earlier age at onset for carriers of the C allele was evaluated. We conclude that IL-6 (-174) polymorphism does not influence the risk of developing AD in our cohort.