Deep DNA metagenomic sequencing reveals oral microbiome divergence between monozygotic twins discordant for multiple sclerosis severity

In contrast to gut, the oral microbiome of MS patients has not been characterized. Deep sequencing of saliva DNA from a pair of monozygotic twins (MSF1 with relapsing remitting MS; MSF2 with clinically isolated syndrome) identified 2036 bacterial species. Relative abundances of 3 phyla were higher, and 3 lower in MSF1 versus MSF2. Species diversity was greater in MSF2, and 20 abundant species differed at least 2-fold. Pathway analysis identified 116 functional hierarchies differing 50% or more. Although limited to one pair of twins, our data suggests that oral microbiome analysis may be useful for diagnosis or monitoring therapeutic efficacy. [Display omitted] •In contrast to the gut, the oral microbiome of MS patients has not been examined.•Shot-gun sequencing of saliva DNA from monozygotic twins discordant for MS identified over 2000 species.•Differences between the twins were present at all taxonomic levels.•Several differences parallel those reported for the gut microbiome between MS and controls.•Examination of the oral microbiome could help inform as to MS diagnosis, severity, and treatment.