Background: Most previous studies have found that human intestinal microbiota affect the symptoms of autism spectrum disorder (ASD), especially gastrointestinal (GI) symptoms, but regarding this, there is limited data of non-western ethnicity. Probiotics can reconstitute the host intestinal microbiota and strengthen gastrointestinal function, however, clinical data proving the effect of probiotics treatment on ASD is lacking.Methods: This study explored the significant differences between ASD and neurotypical (NT), and the improvement of applied behavior analysis (ABA) training in combination with probiotics, vs. ABA training only.Results: We found significant differences between the ASD group and the NT group in the evenness of the intestinal microbiota and the relative abundance of the bacterial phyla and genus. At the phylum level, relative abundance of Bacteroidetes in the ASD group was significantly lower than in the NT group. At the genus level, the relative abundance of Bacteroides, Bifidobacterium, Ruminococcus, Roseburia, and Blautia in the ASD group was significantly lower than that in the NT group. After a 4-week ABA training program in combination with probiotics treatment, the ATEC and GI scores decreased more than the control group with ABA training only.Conclusion: Our findings suggest that intestinal microbiota is different between the NT children and the ASD children with or without GI problems. In combination with ABA training, probiotics treatment can bring more benefit to ASD children. Clinical trials with a more rigorous design and larger sample size are indispensable for further validation.

Fragile X syndrome (FXS) is recognized as the most common genetic cause of intellectual disability and autism spectrum disorder (ASD). Although symptoms of ASD are frequently observed in patients with FXS, researchers have not yet clearly determined whether the symptoms in patients with FXS differ from the symptoms in patients without ASD or nonsyndromic ASD. Behavioral similarities and differences between FXS and ASD are important to improve our understanding of the causes and correlations of ASD with FXS. Based on the evidence presented in this review, individuals with FXS and comorbid ASD have more severe behavioral problems than individuals with FXS alone. However, patients with FXS and comorbid ASD exhibit less severe impairments in the social and communication symptoms than patients with nonsyndromic ASD. Individuals with FXS also present with anxiety and seizures in addition to comorbid ASD symptoms, and differences in these conditions are noted in patients with FXS and ASD. This review also discusses the role of fragile X mental retardation 1 protein (FMRP) in FXS and ASD phenotypes.

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