Bezawada N, et al. - Via performing a systematical review of the existing literature, researchers sought to ascertain the role of the gut microbiota in autism spectrum disorder (ASD). On extensively searching MEDLINE and EMBASE databases from January 1966 through July 2019, they identified a total of 28 papers for inclusion in this work. In these studies, the number of participants ranged from 12 to 104 who were aged between 2 and 18 years and were from various geographical areas. Faecal samples were included in majority of studies; however, there were 4 studies that examined mucosal biopsies from different sites. Autistic children exhibited a significantly higher abundance of the following species: Clostridium, Sutterella, Desulfovibrio and Lactobacillus. However, across the studies, inconsistent findings were recorded and poor consideration was given to the ­potential confounding effects of antimicrobial use, gastrointestinal symptoms, and diet on the gut microbiota. The analysis revealed that patients with ASD exhibit altered gut microbiota, although further investigation is required on whether this is a cause or an effect of the condition.