TNF and amyotrophic lateral sclerosis: Sub-group analyses revealed that blood TNF-α levels were significantly increased in ALS patients compared with normal control subjects (Supplementary Figure 1, Hedges’ g = 0.972; 95% CI, 0.43 to 1.514; p < 0.001), and the high levels of heterogeneity remained for normal control group (Q7 = 48.459; P < 0.001; I2 = 85.555).