FIG 3.

Gut 2-keto-glutaramic acid is a potential marker of ASD. (a) A higher level of gut 2-keto-glutaramic acid is associated with a lower abundance of gut microbiota involved in the d-glutamine and d-glutamate metabolism pathways. (b) A lower abundance of the usually highly abundant Bacteroides vulgatus is significantly correlated with lower levels of d-glutamine and d-glutamate metabolic pathways in the guts of ASD children. (c and d) Significantly lower levels of gut 2-keto-glutaramic acid at the discovery and validation stages, respectively. Values that are significantly different by the Wilcoxon rank sum test are indicated by bars and asterisks as follows: **, P < 0.01; ***, P < 0.001.