Altered gut microbiome diversity and function in patients with propionic acidemia

Propionic acidemia (PA) is an inherited metabolic disorder of propionate metabolism, where the gut microbiota may play a role in pathophysiology and therefore, represent a relevant therapeutic target. Little is known about the gut microbiota composition and activity in patients with PA. Although clinical practice varies between metabolic treatment centers, management of PA requires combined dietary and pharmaceutical treatments, both known to affect the gut microbiota. This study aimed to characterize the gut microbiota and its metabolites in fecal samples of patients with PA compared with healthy controls from the same household. Eight patients (aged 3-14y) and 8 controls (4-31y) were recruited from Center 1 (UK) and 7 patients (11-33y) and 6 controls (15-54y) from Center 2 (Austria). Stool samples were collected 4 times over 3 months, alongside data on dietary intakes and medication usage. Several microbial taxa differed between patients with PA and controls, particularly for Center 1, e.g., Proteobacteria levels were increased, whereas butyrate-producing genera, such as Roseburia and Faecalibacterium, were decreased. Most measured microbial metabolites were lower in patients with PA, and butyrate was particularly depleted in patients from Center 1. Furthermore, microbiota profile of these patients showed the lowest compositional and functional diversity, and lowest stability over 3 months. As the first study to map the gut microbiota of patients with PA, this work represents an important step forward for developing new therapeutic strategies to further improve PA clinical status. New dietary strategies should consider microbial propionate production as well as butyrate production and microbiota stability.