Several new studies have strengthened the link between the gut microbiome and autistic symptoms, increasing the case for making gut microbiome profiling a standard in both diagnoses and as a baseline for microbiome manipulation aimed at symptom alleviation.
In one such study published in Cell, researchers transplanted fecal microbiota from human donors with and without autistic symptoms into germ-free mice to see what effect these transplants would have on the behavior of mice (Sharon et al., 2019). They found that mice whose GI system had been colonized with microbiota from donors without ASD did not display autistic symptoms, while mice with ASD donors consistently displayed autistic symptoms. This provides strong evidence that microbial populations in the gut can be linked to ASD related symptoms.
Another article published in Nature looked at patients with both GI tract disturbances and autistic-related behaviors (Kang et al., 2019). They used fecal microbiota transplant for these patients with the aim of alleviating their GI symptoms and, potentially, their ASD symptoms. Upon completion of the protocol, it was found that the transplants provided significant alleviation of both ASD and GI symptoms; furthermore, the decrease in symptoms was either maintained or even more improved after a two year follow up.
Two more general reviews looking at the connection between the microbiota and autism include Role of the Gut Microbiome in Autism Spectrum Disorders by Pulikkan et al. (2019), and The Gut Microbiota and Autism Spectrum Disorders by Li et al. (2017).
Providing patients with ASD symptoms, especially when in addition to GI disturbance, with a microbiome profile through shotgun metagenomics platforms such as Xplore-PATHO℠ is likely to become routine for therapeutic intervention in the future. As more research looks at the link between ASD and the gut microbiome, we are likely to discover specific microbial populations as causative agents. A baseline for these populations will be a first step in intervention and follow up microbiome profiling will be necessary for tracking the efficacy of treatment.
 Sharon, G., Cruz, N. J., Kang, D.-W., Gandal, M. J., Wang, B., Kim, Y.-M., … Mazmanian, S. K. (2019). Human Gut Microbiota from Autism Spectrum Disorder Promote Behavioral Symptoms in Mice. Cell, 177(6). doi: 10.1016/j.cell.2019.05.004
 Kang, D. W., Adams, J. B., Coleman, D. M., Pollard, E. L., Maldonado, J., McDonough-Means, S., … Krajmalnik-Brown, R. (2019). Long-term benefit of Microbiota Transfer Therapy on autism symptoms and gut microbiota. Scientific reports, 9(1), 5821. doi:10.1038/s41598-019-42183-0
 Pulikkan J., Mazumder A., Grace T. (2019) Role of the Gut Microbiome in Autism Spectrum Disorders. In: Guest P. (eds) Reviews on Biomarker Studies in Psychiatric and Neurodegenerative Disorders. Advances in Experimental Medicine and Biology, vol 1118. Springer, Cham
 Li, Q., Han, Y., Dy, A., & Hagerman, R. J. (2017). The Gut Microbiota and Autism Spectrum Disorders. Frontiers in cellular neuroscience, 11, 120. doi:10.3389/fncel.2017.00120