Introduction
For pediatric diseases like childhood leukemia, a short latency
period points to in-utero exposures as potentially important risk factors.
Untargeted metabolomics of small molecules in archived newborn dried blood
spots (DBS) offers an avenue for discovering early-life exposures that
contribute to disease risks.
Objectives
The purpose of this study was to develop a quantitative method for
untargeted analysis of archived newborn DBS for use in an epidemiological
study (California Childhood Leukemia Study, CCLS).
Methods
Using experimental DBS from the blood of an adult volunteer, we
optimized extraction of small molecules and integrated measurement of
potassium as a proxy for blood hematocrit. We then applied this extraction
method to 4.7-mm punches from 106 control DBS samples from the CCLS. Sample
extracts were analyzed with liquid chromatography high resolution mass
spectrometry (LC-HRMS) and an untargeted workflow was used to screen for
metabolites that discriminate population characteristics such as sex,
ethnicity, and birth weight.
Results
Thousands of small molecules were measured in extracts of archived
DBS. Normalizing for potassium levels removed variability related to varying
hematocrit across DBS punches. Of the roughly 1,000 prevalent small
molecules that were tested, multivariate linear regression detected
significant associations with ethnicity (3 metabolites) and birth weight (15
metabolites) after adjusting for multiple testing.
Conclusions
This untargeted workflow can be used for analysis of small molecules
in archived DBS to discover novel biomarkers, to provide insights into the
initiation and progression of diseases, and to provide guidance for disease
prevention.