CHIT1 and amyotrophic lateral sclerosis: As shown in Fig. 2, the CSF CHIT1 level in patients with ALS was significantly higher than that in the HC (ALS-C pooled SMD, 1.92; 95% CI, 0.78 – 3.06; P < 0.001), and a notable degree of heterogeneity was observed (I2 = 96.5%, P < 0.001).