After a further review, 11 studies were excluded due to the following reasons: 2 articles identified as reviews were first excluded, 2 articles were excluded due to the topic apparently irrelevant to the concern in the current study, 4 articles were also excluded because these studies focused on the association of AD risk and polymorphisms of other genes, 2 articles were excluded for that they concerned the relationship between other polymorphisms of IL-8 gene and AD risk, and 1 article was excluded because of the lack of sufficient data of genotype distribution. The gene discussed is CXCL8; the disease is Alzheimer disease.