IntroductionAutism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social impairment, restricted interest, repetitive behavior, and stereotypical behavioral patterns. Diagnosing ASD presents considerable challenges; a previous large-sample study in children linked ASD and intestinal flora imbalances.MethodsTo explore the composition and functional changes of the gut microbiota in children with ASD, shotgun metagenomic sequencing was used to evaluate the gut microbiota of 78 Chinese children (34 with ASD and 44 with typical development [TD] children).ResultsWe observed differences in the gut microbiota composition and richness between children with ASD and TD in this cohort. The α-diversity of the gut microbiota in the ASD group fluctuated more with age than that in the TD group, based on cross-sectional data. Age-related dynamic changes in the gut bacteria of TD children were not clearly observed in children with ASD. Gut microbiota of children with ASD showed a higher number of antibiotic resistance genes compared to TD. Additionally, the functional gene pathways related to carbohydrate-active enzymes and amino acid metabolism and synthesis appeared reduced in the ASD group.DiscussionThis exploratory study describes key compositional and functional characteristics of the gut microbiota in Chinese children with ASD. Our preliminary findings identify differential bacterial taxa that may be considered as potential candidates for further investigation as fecal markers, and suggest differences in age-related gut microbiota patterns between ASD and TD children. However, due to the modest sample size, cross-sectional design, and lack of external validation, these results should be regarded as a preliminary exploration and require confirmation in larger, independent cohorts.