Study of the Gut Enterotypes in Egyptian Children with Autism Spectrum Disorder

Background: Gut microbiota distribute into three enterotypes named the Bacteroides, Prevotella and Ruminococcus. While each person’s microbial “fingerprint” is unique, there are specific patterns seen in those that are healthy and those that have specific illnesses.

Aims: The aim of the present study is to identify the enterotypes that are likely related to ASD as well as their possible role in the severity of the disease and gastrointestinal symptoms

Subjects & Methods: The study included 41 ASD patients, 45 of their neurotypical siblings and 45 unrelated controls. Autism severity was assessed using Childhood autism rating scale (CARS). Gastrointestinal symptoms were assessed by a modified six-item Gastrointestinal Severity Index (6-GSI) questionnaire. Quantitative real-time SYBR green PCR was done for the identification and quantitation of the dominant enterotypes.

Results: Enterotype 1 (Bacteriodes) was the most prevalent enterotype accounting for 76.7%, 75.6% and 57.8% in patients with autism, their neurotypical siblings and unrelated controls respectively. Enterotype 3 (Ruminococcus dominant), it was detected nearly equal in the three groups. Enterotype 2 (Prevotella dominant), it was the least enterotype encountered in ASD group (4.9%) compared to 8.9% and 22.2% in the siblings and the unrelated control respectively. About 75.6% of ASD patients shared the same enterotype with their siblings. There was no significant difference between the three enterotypes as regards the CARS or 6-GSI.

Conclusion: There was no significant difference in the distribution of enterotypes in all study groups. Therefore, collapsing the whole microbiome variations into dominant enterotypes was not appropriate to identify disease association or to be used as a disease biomarker. Further studies of individual bacterial species may be more accurate to determine if there are any possible correlations between the gut microbiome and the gastrointestinal dysfunction in ASD patients.