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BackgroundMetals exposures have important health effects in pregnancy. The maternal epigenome may be responsive to these exposures. We tested whether metals are associated with concurrent differential maternal whole blood DNA methylation.MethodsIn the Early Autism Risk Longitudinal Investigation (EARLI) cohort, we measured first or second trimester maternal blood metals concentrations (cadmium, lead, mercury, manganese, and selenium) in 215 participants using inductively coupled plasma mass spectrometry. DNA methylation in maternal whole blood was measured in the same specimens on the Illumina 450K array (201 participants). A subset sample of 97 women had both measures available for analysis, all of whom did not report smoking during pregnancy. Linear regression was used to test for site-specific associations between individual metals and DNA methylation, adjusting for cell type composition and confounding variables. Discovery gene ontology analysis was conducted on the top 1,000 sites associated with each metal to elucidate downstream pathways.ResultsIn multiple linear regression, we observed hypermethylation at 11 DNA methylation sites associated with lead (FDR q-value CYP24A1, ASCL2, FAT1, SNX31, NKX6-2, LRC4C, BMP7, HOXC11, PCDH7, ZSCAN18, and VIPR2. Lead associated sites were enriched (FDR q-value ARID2. Manganese associated sites were enriched for cellular metabolism pathways (FDR q-value0.86).DiscussionSingle DNA methylation sites associated with lead and manganese may be potential biomarkers of exposure or implicate downstream gene pathways. Future studies should replicate our findings to characterize potential toxicological mechanisms of trace metals through the maternal epigenome.

BackgroundAutism spectrum disorder (ASD) is a neurodevelopmental disorder that affects more than 1% of children in the USA. ASD risk is thought to arise from both genetic and environmental factors, with the perinatal period as a critical window. Understanding early transcriptional changes in ASD would assist in clarifying disease pathogenesis and identifying biomarkers. However, little is known about umbilical cord blood gene expression profiles in babies later diagnosed with ASD compared to non-typically developing and non-ASD (Non-TD) or typically developing (TD) children.MethodsGenome-wide transcript levels were measured by Affymetrix Human Gene 2.0 array in RNA from cord blood samples from both the Markers of Autism Risk in Babies-Learning Early Signs (MARBLES) and the Early Autism Risk Longitudinal Investigation (EARLI) high-risk pregnancy cohorts that enroll younger siblings of a child previously diagnosed with ASD. Younger siblings were diagnosed based on assessments at 36 months, and 59 ASD, 92 Non-TD, and 120 TD subjects were included. Using both differential expression analysis and weighted gene correlation network analysis, gene expression between ASD and TD, and between Non-TD and TD, was compared within each study and via meta-analysis.ResultsWhile cord blood gene expression differences comparing either ASD or Non-TD to TD did not reach genome-wide significance, 172 genes were nominally differentially expressed between ASD and TD cord blood (log2(fold change) > 0.1,p q LimitationsASD-associated gene expression differences identified in this study are subtle, as cord blood is not the main affected tissue, it is composed of many cell types, and ASD is a heterogeneous disorder.ConclusionsThis is the first study to identify gene expression differences in cord blood specific to ASD through a meta-analysis across two prospective pregnancy cohorts. The enriched gene pathways support involvement of environmental, immune, and epigenetic mechanisms in ASD etiology.