For IL-6-174 G/C polymorphism, the combined results based on all studies showed the evidence of an association between the decreased risk of AD and the variant genotypes in recessive model (CC vs. CG+GG: OR  = 0.65, 95% CI = 0.52–0.82, P = 0.0003, Figure 2). Here, IL6 is linked to Alzheimer disease.