Sensitivity analysis was performed to determine the source of heterogeneity, and the results showed that excluding one study [31] considerably reduced the between-study heterogeneity, resulting in a statistically significant increase in basal monocytic TLR4 density in persons with schizophrenia compared to HCs (Hedges’ g = 0.469, 95% CI: 0.195 to 0.742, p = 0.001) (Fig 3-A). The gene discussed is TLR4; the disease is schizophrenia.