Identifying gut microbiota composition disparities in autistic individuals and their unaffected siblings: correlations with clinical characteristics

Recent research has begun to illuminate a potential link between autism spectrum disorder (ASD) and the microbial environment. The unaffected sibling design is a valuable approach to identifying markers and protective factors for the condition, particularly in Asian populations lacking specific data. We assessed 239 autistic individuals, 102 unaffected siblings (SIB), and 81 typically developing controls (TDC) aged 4 to 25 years. We analyzed fresh stool samples via 16S rRNA amplicon library preparation and Illumina V3V4 sequencing. We employed taxonomic diversity analysis and microbiota differential abundance analysis to discern variations in microbial composition. In addition, we analyzed the associations between microbiota profiles and autistic symptoms, emotional/behavioral problems, and gastrointestinal symptoms. The SIB had higher alpha diversity, and autistic individuals had a different beta diversity compared to the TDC. Compared to ASD and SIB, the TDC group exhibited a higher relative abundance of microbiota, including Blautia, Eubacterium hallii group, Anaerostipes, Erysipelotrichaceae UCG 003, Parasutterella, and Ruminococcaceae UCG 013 at the genus level. Furthermore, the family Prevotellaceae and genera Agathobacter were predominant in SIB compared to ASD and TDC. We found that the microbial communities were related to autistic symptoms and gastrointestinal symptoms. Moreover, individuals with more Anaerostipes exhibited significantly less social impairment and internalizing problems. Our study reveals unique microbial compositions in the ASD and SIB groups and a relationship between behavior patterns and microbial composition. These findings suggest the potential of microbial interventions for autistic individuals that warrant further exploration.