Childhood adversity and DNA methylation in two population-based cohorts.

Childhood adversity affects later health, but the underlying molecular mechanisms are unclear. Although there is some evidence from animal models and case-control studies of a role for DNA methylation, evidence from human population-based studies is limited. In two cohorts (mothers from the Avon Longitudinal Study of Parents and Children, ALSPAC, n = 780 and women from the MRC National Survey of Health and Development, NSHD, n = 552), we assessed the association of seven adverse childhood experiences (ACEs: parental physical illness, parental mental illness, parental death, parental separation, suboptimal maternal bonding, childhood illness and child maltreatment) as well as their combination (ACE score) with genome-wide DNA methylation levels measured using the Illumina Infinium HumanMethylation450 BeadChip in peripheral blood at mean age 47 years (ALSPAC) and in buccal cells at age 53 years (NSHD). CpG sites with a genome-wide false discovery rate (FDR) below 0.05 and differentially methylated regions (DMRs) with one-step Sidák correction p-values below 0.05 in each cohort were examined in the other cohort. No individual CpG sites replicated across cohorts. However, nine DMRs replicated across cohorts respectively associated with the ACE score (one region), parental mental illness (two regions), parental physical illness (three regions) and parental death (three regions). These observations indicate that some adverse childhood experiences, notably those related to parental health, may leave imprints on peripheral DNA methylation that persist to mid-life.

Ankyrin-3 as a molecular marker of early-life stress and vulnerability to psychiatric disorders.

Exposure to early-life stress (ELS) may heighten the risk for psychopathology at adulthood. Here, in order to identify common genes that may keep the memory of ELS through changes in their methylation status, we intersected methylome analyses performed in different tissues and time points in rats, non-human primates and humans, all characterized by ELS. We identified Ankyrin-3 (Ank3), a scaffolding protein with a strong genetic association for psychiatric disorders, as a gene persistently affected by stress exposure. In rats, Ank3 methylation and mRNA changes displayed a specific temporal profile during the postnatal development. Moreover, exposure to prenatal stress altered the interaction of ankyrin-G, the protein encoded by Ank3 enriched in the post-synaptic compartment, with PSD95. Notably, to model in humans a gene by early stress interplay on brain phenotypes during cognitive performance, we demonstrated an interaction between functional variation in Ank3 gene and obstetric complications on working memory in healthy adult subjects. Our data suggest that alterations of Ank3 expression and function may contribute to the effects of ELS on the development of psychiatric disorders.

MORC1 exhibits cross-species differential methylation in association with early life stress as well as genome-wide association with MDD.

Early life stress (ELS) is associated with increased vulnerability for diseases in later life, including psychiatric disorders. Animal models and human studies suggest that this effect is mediated by epigenetic mechanisms. In humans, epigenetic studies to investigate the influence of ELS on psychiatric phenotypes are limited by the inaccessibility of living brain tissue. Due to the tissue-specific nature of epigenetic signatures, it is impossible to determine whether ELS induced epigenetic changes in accessible peripheral cells, for example, blood lymphocytes, reflect epigenetic changes in the brain. To overcome these limitations, we applied a cross-species approach involving: (i) the analysis of CD34+ cells from human cord blood; (ii) the examination of blood-derived CD3+ T cells of newborn and adolescent nonhuman primates (Macaca mulatta); and (iii) the investigation of the prefrontal cortex of adult rats. Several regions in MORC1 (MORC family CW-type zinc finger 1; previously known as: microrchidia (mouse) homolog) were differentially methylated in response to ELS in CD34+ cells and CD3+ T cells derived from the blood of human and monkey neonates, as well as in CD3+ T cells derived from the blood of adolescent monkeys and in the prefrontal cortex of adult rats. MORC1 is thus the first identified epigenetic marker of ELS to be present in blood cell progenitors at birth and in the brain in adulthood. Interestingly, a gene-set-based analysis of data from a genome-wide association study of major depressive disorder (MDD) revealed an association of MORC1 with MDD.