# Fecal microbiota and genetics in pediatric-onset orofacial granulomatosis and Crohn´s disease

## TL;DR

This study compares the gut microbiota and genetic markers in children with orofacial granulomatosis and Crohn's disease to determine if they are distinct conditions.

## Contribution

The study identifies unique microbial and genetic profiles in pediatric-onset orofacial granulomatosis compared to Crohn's disease.

## Key findings

- OFG patients showed decreased Clostridia and increased Actinobacteria and Bacilli compared to CD and healthy controls.
- Bifidobacterium adolescentis increased while Faecalibacterium prausnitzii decreased with higher oral disease activity in OFG.
- The NOD2 gene variant rs8057341 allele A was more common in OFG than in CD patients.

## Abstract

Orofacial granulomatosis (OFG) is a rare chronic inflammatory condition. It is under debate, whether it is a condition of its own or merely a subtype of Crohn’s disease (CD). We aimed to search for markers characteristic of patients with pediatric-onset OFG compared to patients with pediatric-onset CD. We recruited young patients with OFG (with or without CD, n = 29), CD (n = 24), and healthy controls (n = 20). All participants provided a fecal sample for microbiota and calprotectin analyses and saliva for DNA analysis of genes associated with OFG and kept a 3-day food diary. Oral disease activity was evaluated using The Oral Disease Activity Score by an otorhinolaryngologist and a dentist. We observed decreased relative abundance in class Clostridia and increased relative abundances of classes Actinobacteria and Bacilli in the feces of patients with OFG when compared to patients with CD and healthy controls. The relative abundances of Bifidobacterium adolescentis increased and Faecalibacterium prausnitzii decreased along with the increase in the Oral Disease Activity Score. We found the NOD2 gene rs8057341 allele A to be enriched in patients with OFG compared to patients with CD. These findings support the theory that OFG is a distinct disease phenotype.

The online version contains supplementary material available at 10.1038/s41598-025-90243-5.