Exploring the gut microbiome in children and young adults with myotonic dystrophy type 1

Myotonic Dystrophy type 1 (DM1) is a complex multisystem disorder, and affected children commonly present with gastrointestinal and neurodevelopmental challenges. Despite the high prevalence of these symptoms, their underlying mechanisms remain poorly understood. The gut microbiome is known to be involved in gastrointestinal and neurodevelopmental disorders, and emerging research suggests that it could also play a contributory role in various neuromuscular diseases. However, the gut microbiota of children with DM1 remains unexplored. This pilot study compared gut microbiota profiles of 10 children and one young adult with DM1, to that of their unaffected siblings (n=11). Three-day food records and faecal samples were collected, and bacterial taxa were analysed through 16S rRNA marker-gene sequencing. A within-family paired-sample design accounted for potential confounders, such as diet and lifestyle. Results revealed that overall microbial diversity and community structure were similar between groups. Moreover, participants with DM1 showed a significant lower relative abundance of the bacterial genus Faecalibacterium (mean 4.9% ± 2.1%) compared to their unaffected siblings (mean 9.1% ± 4.4%)(p=0.005). This finding should be considered exploratory, as its univariate analysis was uncorrected for multiple testing. Faecalibacterium is a key gut bacterium, and reduced abundance has been reported in several DM1-associated gastrointestinal and neurodevelopmental disorders. Although causality cannot be inferred from this exploratory study the observed reduction may be relevant to gastrointestinal and neurodevelopmental challenges frequently seen in DM1. If larger further studies confirm its role, targeting Faecalibacterium relative abundance could become a potential therapeutic strategy for alleviating gastrointestinal and neurodevelopmental symptoms in DM1.