ABSTRACT
Background: Autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and schizophrenia (SCZ) are highly heritable and linked to disruptions in foetal (neuro)development. While epigenetic processes are considered an important underlying pathway between genetic susceptibility and neurodevelopmental conditions, it is unclear (i) whether genetic susceptibility to these conditions is associated with epigenetic patterns, specifically DNA methylation (DNAm), already at birth; (ii) to what extent DNAm patterns are unique or shared across conditions, and (iii) whether these neonatal DNAm patterns can be leveraged to enhance genetic prediction of (neuro)developmental outcomes. Methods: We conducted epigenome-wide meta-analyses of genetic susceptibility to ASD, ADHD, and schizophrenia, quantified using polygenic scores (PGSs) on cord blood DNAm, using four population-based cohorts (n pooled=5,802), all North European. Heterogeneity statistics were used to estimate overlap in DNAm patterns between PGSs. Subsequently, DNAm-based measures of PGSs were built in a target sample, and used as predictors to test incremental variance explained over PGS in 130 (neuro)developmental outcomes spanning birth to 14 years. Outcomes: In probe-level analyses, SCZ-PGS associated with neonatal DNAm at 246 loci (p<9×10-8), predominantly in the major histocompatibility complex. Functional characterization of these DNAm loci confirmed strong genetic effects, significant blood-brain concordance and enrichment for immune-related pathways. 8 loci were identified for ASD-PGS (mapping to FDFT1 and MFHAS1), and none for ADHD-PGS. Regional analyses indicated a large number of differentially methylated regions for all PGSs (SCZ-PGS: 157, ASD-PGS: 130, ADHD-PGS: 166). DNAm signals showed little overlap between PGSs. We found suggestive evidence that incorporating DNAm-based measures of genetic susceptibility at birth increases explained variance for several child cognitive and motor outcomes over and above PGS. Interpretation: Genetic susceptibility for neurodevelopmental conditions, particularly schizophrenia, is detectable in cord blood DNAm at birth in a population-based sample, with largely distinct DNAm patterns between PGSs. These findings support an early-origins perspective on schizophrenia. Funding: HorizonEurope; European Research Council.
ABSTRACT
At the same temperature and with adequate circulation of blood or receptor solution beneath it the permeability of the stratum corneum of the rabbit ear to T2O or to 32P-TPP was the same in vivo as in vitro. When skin permeability was measured in vitro, the subcutaneous adipose tissue present in the full-thickness skin of the rat delayed the penetration of CR, a lipophilic substance with a low water solubility, and decreased the permeability constant by nearly 3x. The retardant solvent PEG 300 did not penetrate the stratum corneum; it formed a hydrogen-bonded complex with the cholinesterase inhibitor VX, thereby reducing the thermodynamic activity and penetration rate of this compound through the stratum corneum. The accelerant solvent DMSO removed protein components from the stratum corneum; electron microscope studies showed that the cells of stratum corneum so treated became separated from one another, and their contents became stainable in bulk with Pb++, indicating the creation of new diffusion pathways. When the temperature, clearance of penetrant from the lower surface of the stratum corneum and penetrant formulation were the same in vivo as in vitro, and the surface of the stratum corneum was saturated with the penetrant or its solution, the results of permeability measurements made in vivo were similar to those made in vitro.