The review board rejected our request of changing the protocol and advised us to terminate the trial.

To explore the efficacy of fecal microbiota transplantation (FMT) in improving the gastrointestinal symptoms and autism symptoms in patients diagnosed as autism spectrum disorder (ASD) comorbid with gastrointestinal symptoms.

This trial is designed to reconstruct the intestinal micro-ecology of children with ASD by the interventional treatment of FMT. At the same time, combined with metagenomics and 16S rRNA sequencing techniques, the trial aims to study the efficacy of intestinal micro-ecology for the treatment of autism symptoms and the improvement of gastrointestinal problems and autism symptoms in autistic patients, and to explore potential new techniques for treating children with ASD.

Inclusion Criteria:

1. Patients diagnosed with ASD. Diagnostic criteria: diagnosed by pediatric psychiatrists in accordance with the criteria in the Fifth Edition of Diagnostic and Statistical Manual of Mental Disorders (DSM-V), Autism Diagnostic Observation Schedule (ADOS) and Autism Diagnostic Interview-Revised (ADI-R);
2. Patients with moderate to severe gastrointestinal symptoms which are not life-threatening and do not require immediate surgery;
3. Patients aged 3-17 years, male or female;
4. Patients who are suitable for receiving oral FMT capsules, and able to swallow the capsules without chewing;
5. Patients who are able to complete the study as required by the trial protocol;
6. Patients without known immunodeficiency diseases;
7. Subjects and/or their guardians are able to fully understand the informed consent of the trial, and voluntarily sign the informed consent form.

Exclusion Criteria：

1. Patients diagnosed with severe malnutrition;
2. Patients depend on tube feeding (liquid food);
3. Patients with a serious gastrointestinal disease requiring immediate treatment (or life-threatening);
4. Patients with primary immunodeficiency disease during screening;
5. Patients with a single-gene disorder;
6. Patients with a history of severe allergies;
7. Patients with severe fever and/or serious infection within 7 days prior to enrollment;
8. Patients with renal insufficiency and liver dysfunction (or creatinine > 2 mg/dl, direct bilirubin > 2 mg/dl);
9. Subjects with congenital or acquired immunodeficiency or immunosuppression (e.g., neoplastic disease or organ transplant) who have received or are undergoing chemotherapy, or have been diagnosed with HIV;
10. Patients with inflammatory bowel disease, celiac disease, large intestine irritation or eosinophilia, esophagitis, eosinophilic gastroenteritis or similar diseases;
11. Subjects with severe sensory or motor disorders (e.g., blindness, deafness, seizures, cerebral palsy);
12. Patients who are participating in other clinical studies, or have received interventions in other interventional clinical studies within 4 weeks prior to enrollment.