On the other hand, IFN-γ (OR 0.303, 95% CI 0.205 to 0.402; p < 0.001), IL-9 (OR 0.072, 95% CI 0.013 to 0.130; p = 0.016), IL-17 (OR 0.095, 95% CI 0.011 to 0.179; p = 0.027), and IL-22 (OR 0.215, 95% CI 0.140 to 0.290; p < 0.001) levels were positively correlated with the occurrence of AD; while IL-4 (OR −0.222, 95% CI −0.318 to −0.125; p < 0.001) and IL-35 (OR −0.161, 95% CI −0.243 to −0.079; p < 0.001) levels were negatively correlated with the occurrence of AD (as shown in Table 5). The gene discussed is IL17A; the disease is Alzheimer disease.