# An untargeted comparative metabolomics analysis of infants with and without late-onset breast milk jaundice

## TL;DR

This study compares the fecal metabolites of infants with and without late-onset breast milk jaundice to understand potential biological mechanisms behind the condition.

## Contribution

The study provides new insights into the metabolic differences associated with late-onset breast milk jaundice using untargeted metabolomics.

## Key findings

- PCA and cluster analysis revealed significant differences in fecal metabolites between infants with and without LBMJ.
- Differential metabolites were enriched in pathways like Biotin metabolism, N-Glycan biosynthesis, and Taurine metabolism.
- Over 2000 differential metabolites were identified, with distinct up and down regulation patterns in both ion modes.

## Abstract

Background: Late-onset breast milk jaundice (LBMJ) is a common form of hyperbilirubinemia, which can result in serious complications for newborns with persistently high bilirubin levels. The aim of this study was to investigate the differences in fecal metabolites between breastfed infants with and without LBMJ in order to elucidate potential biological mechanisms. Methods: Biological samples were collected from 12 infants with LBMJ and 12 healthy individuals. Ultra-high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS) was utilized for non-targeted determination of fecal metabolites. Principal components analysis (PCA), cluster analysis, and differential metabolite analysis were performed in both positive ion mode and negative ion mode for the two groups. Additionally, the KEGG database was employed to comprehensively analyze the pathways of differential metabolites. Results: There were no significant differences in maternal and neonatal demographic characteristics between the two groups (p > 0.05). The results of PCA and cluster heat map analysis in both modes showed that there were significant differences in metabolites between the two groups. Among 751 differential metabolites (DMs) detected in positive ion mode, 720 were up-regulated in the case group while 31 were down-regulated. In negative ion mode, 1891 DMs were detected, including 817 up-regulated metabolites and 1074 down-regulated metabolites in the case group. Analysis of differential metabolic pathways showed that the DMs of the two groups were mainly annotated and enriched in Biotin metabolism, N-Glycan biosynthesis, Taurine and hypotaurine metabolism, Pyrimidine metabolism, and Pentose and glucuronate interconversions. Conclusion: Significant differences exist in fecal metabolites between LBMJ infants and healthy controls. The study of differential metabolic pathways provides insights into the mechanism of LBMJ.