Sex-specific epigenetic disruption and behavioral changes following low-dose in utero bisphenol A exposure

Bisphenol A (BPA) is an estrogenic endocrine disruptor widely used in the production of plastics. Increasing evidence indicates that in utero BPA exposure affects sexual differentiation and behavior; however, the mechanisms underlying these effects are unknown. We hypothesized that BPA may disrupt epigenetic programming of gene expression in the brain. Here, we provide evidence that maternal exposure during pregnancy to environmentally relevant doses of BPA (2, 20, and 200 µg/kg/d) in mice induces sex-specific, dose-dependent (linear and curvilinear), and brain region-specific changes in expression of genes encoding estrogen receptors (ERs; ERα and ERβ) and estrogen-related receptor-γ in juvenile offspring. Concomitantly, BPA altered mRNA levels of epigenetic regulators DNA methyltransferase (DNMT) 1 and DNMT3A in the juvenile cortex and hypothalamus, paralleling changes in estrogen-related receptors. Importantly, changes in ERα and DNMT expression in the cortex (males) and hypothalamus (females) were associated with DNA methylation changes in the ERα gene. BPA exposure induced persistent, largely sex-specific effects on social and anxiety-like behavior, leading to disruption of sexually dimorphic behaviors. Although postnatal maternal care was altered in mothers treated with BPA during pregnancy, the effects of in utero BPA were not found to be mediated by maternal care. However, our data suggest that increased maternal care may partially attenuate the effects of in utero BPA on DNA methylation. Overall, we demonstrate that low-dose prenatal BPA exposure induces lasting epigenetic disruption in the brain that possibly underlie enduring effects of BPA on brain function and behavior, especially regarding sexually dimorphic phenotypes.     

Persistent epigenetic differences associated with prenatal exposure to famine in humans

Extensive epidemiologic studies have suggested that adult disease risk is associated with adverse environmental conditions early in development. Although the mechanisms behind these relationships are unclear, an involvement of epigenetic dysregulation has been hypothesized. Here we show that individuals who were prenatally exposed to famine during the Dutch Hunger Winter in 1944–45 had, 6 decades later, less DNA methylation of the imprinted IGF2 gene compared with their unexposed, same-sex siblings. The association was specific for periconceptional exposure, reinforcing that very early mammalian development is a crucial period for establishing and maintaining epigenetic marks. These data are the first to contribute empirical support for the hypothesis that early-life environmental conditions can cause epigenetic changes in humans that persist throughout life.     

Maternal nutrient supplementation counteracts bisphenol A-induced DNA hypomethylation in early development

The hypothesis of fetal origins of adult disease posits that early developmental exposures involve epigenetic modifications, such as DNA methylation, that influence adult disease susceptibility. In utero or neonatal exposure to bisphenol A (BPA), a high-production-volume chemical used in the manufacture of polycarbonate plastic, is associated with higher body weight, increased breast and prostate cancer, and altered reproductive function. This study shows that maternal exposure to this endocrine-active compound shifted the coat color distribution of viable yellow agouti (Avy) mouse offspring toward yellow by decreasing CpG (cytosine-guanine dinucleotide) methylation in an intracisternal A particle retrotransposon upstream of the Agouti gene. CpG methylation also was decreased at another metastable locus, the CDK5 activator-binding protein (CabpIAP). DNA methylation at the Avy locus was similar in tissues from the three germ layers, providing evidence that epigenetic patterning during early stem cell development is sensitive to BPA exposure. Moreover, maternal dietary supplementation, with either methyl donors like folic acid or the phytoestrogen genistein, negated the DNA hypomethylating effect of BPA. Thus, we present compelling evidence that early developmental exposure to BPA can change offspring phenotype by stably altering the epigenome, an effect that can be counteracted by maternal dietary supplements.     

Neonatal exposure to estradiol/bisphenol A alters promoter methylation and expression of Nsbp1 and Hpcal1 genes and transcriptional programs of Dnmt3a/b and Mbd2/4 in the rat prostate gland throughout life

Evidence supporting an early origin of prostate cancer is growing. We demonstrated previously that brief exposure of neonatal rats to estradiol or bisphenol A elevated their risk of developing precancerous lesions in the prostate upon androgen-supported treatment with estradiol as adults. Epigenetic reprogramming may be a mechanism underlying this inductive event in early life, because we observed overexpression of phosphodiesterase 4D variant 4 (Pde4d4) through induction of hypomethylation of its promoter. This epigenetic mark was invisible in early life (postnatal d 10), becoming apparent only after sexual maturation. Here, we asked whether other estrogen-reprogrammable epigenetic marks have similar or different patterns in gene methylation changes throughout life. We found that hypomethylation of the promoter of nucleosome binding protein-1 (Nsbp1), unlike Pde4d4, is an early and permanent epigenetic mark of neonatal exposure to estradiol/bisphenol A that persists throughout life, unaffected by events during adulthood. In contrast, hippocalcin-like 1 (Hpcal1) is a highly plastic epigenetic mark whose hypermethylation depends on both type of early-life exposure and adult-life events. Four of the eight genes involved in DNA methylation/demethylation showed early and persistent overexpression that was not a function of DNA methylation at their promoters, including genes encoding de novo DNA methyltransferases (Dnmt3a/b) and methyl-CpG binding domain proteins (Mbd2/4) that have demethylating activities. Their lifelong aberrant expression implicates them in early-life reprogramming and prostate carcinogenesis during adulthood. We speculate that the distinctly different fate of early-life epigenetic marks during adulthood reflects the complex nature of lifelong editing of early-life epigenetic reprogramming.     

Hepatic DNA methylation modifications in early development of rats resulting from perinatal BPA exposure contribute to insulin resistance in adulthood

Aims/hypothesis

Perinatal exposure to bisphenol A (BPA), a widely distributed environmental endocrine disruptor, is associated with insulin resistance and diabetes in offspring. The underlying molecular mechanisms could involve epigenetics, as adverse effects induced by environmental exposure in early life are suggested through DNA methylation. In this study we sought to elucidate the relationship between perinatal BPA exposure and alteration of hepatic DNA methylation.

Methods

Pregnant Wistar rats were administered BPA (50 μg/kg/day) or corn oil by oral gavage throughout gestation and lactation. Variables associated with insulin resistance and hepatic DNA methylation were examined at postnatal week 3 and week 21 in male offspring.

Results

In BPA-treated offspring, serum insulin and HOMA-insulin resistance were increased, and the insulin sensitivity index and hepatic glycogen storage were decreased compared with controls at week 21. At week 3, none of these variables were significantly changed. However, hepatic global DNA methylation was decreased, accompanied by overexpression of DNA methyltransferase 3B mRNA at week 3. Meanwhile, perinatal exposure to BPA induced promoter hypermethylation and a reduction in gene expression of hepatic glucokinase. Moreover, increased promoter hypermethylation of Gck became more pronounced in BPA-treated offspring at week 21.

Conclusions/interpretation

Abnormal DNA methylation in hepatic tissue precedes development of insulin resistance induced by perinatal BPA exposure. These findings support the potential role of epigenetics in fetal reprogramming by BPA-induced metabolic disorders.     

Epigenetics and Development of Food Allergy (FA) in Early Childhood

This review aims to highlight the latest advance on epigenetics in the development of food allergy (FA) and to offer future perspectives. FA, a condition caused by an immunoglobulin (Ig) E-mediated hypersensitivity reaction to food, has emerged as a major clinical and public health problem worldwide in light of its increasing prevalence, potential fatality, and significant medical and economic impact. Current evidence supports that epigenetic mechanisms are involved in immune regulation and that the epigenome may represent a key “missing piece” of the etiological puzzle for FA. There are a growing number of population-based epigenetic studies on allergy-related phenotypes, mostly focused on DNA methylation. Previous studies mostly applied candidate-gene approaches and have demonstrated that epigenetic marks are associated with multiple allergic diseases and/or with early-life exposures relevant to allergy development (such as early-life smoking exposure, air pollution, farming environment, and dietary fat). Rapid technological advancements have made unbiased genome-wide DNA methylation studies highly feasible, although there are substantial challenge in study design, data analyses, and interpretation of findings. In conclusion, epigenetics represents both an important knowledge gap and a promising research area for FA. Due to the early onset of FA, epigenetic studies of FA in prospective birth cohorts have the potential to better understand gene-environment interactions and underlying biological mechanisms in FA during critical developmental windows (preconception, in utero, and early childhood) and may lead to new paradigms in the diagnosis, prevention, and management of FA and provide novel targets for future drug discovery and therapies for FA.     

DNA Methylation Profile of Genes Involved in Inflammation and Autoimmunity in Inflammatory Bowel Disease

The contribution of epigenetic alterations to disease pathogenesis is emerging as a research priority. In this study, we aimed to seek DNA methylation changes in peripheral blood and tissue biopsies from patients with inflammatory bowel disease.The promoter methylation status of genes involved in inflammation and autoimmunity was profiled using the Human Inflammatory Response and Autoimmunity EpiTect Methyl II Signature PCR Array profiles. Methylation was considered to be hypermethylated if >20% according to the instructions of the manufacturer. The microarrays were validated with Quantitative Real-time PCR.Regarding Crohn disease (CD) no gene appeared hypermethylated compared to healthy controls. In ulcerative colitis (UC) 5 genes (CXCL14, CXCL5, GATA3, IL17C, and IL4R) were hypermethylated compared to healthy controls. Some of the examined genes show different methylation patterns between CD and UC. Concerning tissue samples we found that all hypermethylated genes appear the same methylation pattern and confirmed a moderate–strong correlation between methylation levels in colon biopsies and peripheral blood (Pearson coefficients r = 0.089–0.779, and r = 0.023–0.353, respectively).The epigenetic changes observed in this study indicate that CD and UC exhibit specific DNA methylation signatures with potential clinical applications in IBD non-invasive diagnosis and prognosis.     

Specific premature epigenetic aging of cartilage in osteoarthritis

Osteoarthritis (OA) is a disease affecting multiple tissues of the joints in the elderly, but most notably articular cartilage. Premature biological aging has been described in this tissue and in blood cells, suggesting a systemic component of premature aging in the pathogenesis of OA. Here, we have explored epigenetic aging in OA at the local (cartilage and bone) and systemic (blood) levels. Two DNA methylation age-measures (DmAM) were used: the multi-tissue age estimator for cartilage and bone; and a blood-specific biomarker for blood. Differences in DmAM between OA patients and controls showed an accelerated aging of 3.7 years in articular cartilage (95 % CI = 1.1 to 6.3, P = 0.008) of OA patients. By contrast, no difference in epigenetic aging was observed in bone (0.04 years; 95 % CI = −1.8 to 1.9, P = 0.3) and in blood (−0.6 years; 95 % CI = −1.5 to 0.3, P = 0.2) between OA patients and controls. Therefore, premature epigenetic aging according to DNA methylation changes was specific of OA cartilage, adding further evidence and insight on premature aging of cartilage as a component of OA pathogenesis that reflects damage and vulnerability.     

Cardiac and vascular structure and function parameters do not improve with alternate nightly home hemodialysis: An interventional cohort study

Background

Renal kallikrein (KLK1) synthesis and urinary excretion are reportedly diminished during AKI (acute kidney injury) in animal models, and provision of kallikrein abrogates renal injury in this setting, but data in human AKI is limited. Therefore we first examined KLK1 renal excretion in human AKI, and then probed potential endocrine and epigenetic mechanisms for its alterations.

Methods

KLK1 enzymatic activity excretion was evaluated in urine from patients with established or incipient AKI, versus healthy/non-hospital as well as ICU controls. Endocrine control of KLK1 excretion was then probed by catecholamine and aldosterone measurements in established AKI versus healthy controls. To examine epigenetic control of KLK1 synthesis, we tested blood and urine DNA for changes in promoter CpG methylation of the KLK1 gene, as well as LINE-1 elements, by bisulfite sequencing.

Results

Patients with early/incipient AKI displayed a modest reduction of KLK1 excretion, but unexpectedly, established AKI displayed substantially elevated urine KLK1 excretion, ~11-fold higher than healthy controls, and ~3-fold greater than ICU controls. We then probed potential mechanisms of the change. Established AKI patients had lower SBP, higher heart rate, and higher epinephrine excretion than healthy controls, though aldosterone excretion was not different. Promoter KLK1 CpG methylation was higher in blood than urine DNA, while KLK1 methylation in blood DNA was significantly higher in established AKI than healthy controls, though KLK1 methylation in urine tended to be higher in AKI, directionally consistent with earlier/incipient but not later/established changes in KLK1 excretion in AKI. On multivariate ANOVA, AKI displayed coordinate changes in KLK1 excretion and promoter methylation, though directionally opposite to expectation. Control (LINE-1 repetitive element) methylation in blood and urine DNA was similar between AKI and controls.

Conclusions

Unexpectedly, increased KLK1 excretion in AKI patients was found; this increase is likely to be due in part to increments in adrenergic tone during BP depression. Epigenetic changes at KLK1 may also play a role in early changes of KLK1 expression and thus AKI susceptibility or recovery.     

Long‐lasting neurotoxic effects of exposure to methylmercury during development

Amongst environmental chemical contaminants, methylmercury (MeHg) remains a major concern because of its detrimental effects on developing organisms, which appear to be particularly susceptible to its toxicity. Here, we investigated the effects of low MeHg levels on the development of the nervous system using both in vitro and in vivo experimental models. In neural stem cells (NSCs), MeHg decreased proliferation and neuronal differentiation and induced cellular senescence associated with impairment in mitochondrial function and a concomitant decrease in global DNA methylation. Interestingly, the effects were heritable and could be observed in daughter NSCs never directly exposed to MeHg. By chronically exposing pregnant/lactating mice to MeHg, we found persistent behavioural changes in the male offspring, which exhibited depression‐like behaviour that could be reversed by chronic treatment with the antidepressant fluoxetine. The behavioural alterations were associated with a decreased number of proliferating cells and lower expression of brain‐derived neurotrophic factor (Bdnf) mRNA in the hippocampal dentate gyrus. MeHg exposure also induced long‐lasting DNA hypermethylation, increased histone H3‐K27 tri‐methylation and decreased H3 acetylation at the Bdnf promoter IV, indicating that epigenetic mechanisms play a critical role in mediating the long‐lasting effects of perinatal exposure to MeHg. Fluoxetine treatment restored the Bdnf mRNA expression levels, as well as the number of proliferating cells in the granule cell layer of the dentate gyrus, which further supports the hypothesis that links depression to impaired neurogenesis. Altogether, our findings have shown that low concentrations of MeHg induce long‐lasting effects in NSCs that can potentially predispose individuals to depression, which we have reported earlier to occur in experimental animals exposed to MeHg during prenatal and early postnatal development.     

Prenatal synthetic glucocorticoid treatment changes DNA methylation states in male organ systems: multigenerational effects

Prenatal synthetic glucocorticoids (sGC) are administered to pregnant women at risk of delivering preterm, approximately 10% of all pregnancies. Animal studies have demonstrated that offspring exposed to elevated glucocorticoids, either by administration of sGC or as a result of maternal stress, are at increased risk of developing behavioral, endocrine, and metabolic abnormalities. DNA methylation is a covalent modification of DNA that plays a critical role in long-lasting programming of gene expression. Here we tested the hypothesis that prenatal sGC treatment has both acute and long-term effects on DNA methylation states in the fetus and offspring and that these effects extend into a subsequent generation. Pregnant guinea pigs were treated with sGC in late gestation, and methylation analysis by luminometric methylation assay was undertaken in organs from fetuses and offspring across two generations. Expression of genes that modify the epigenetic state were measured by quantitative real-time PCR. Results indicate that there are organ-specific developmental trajectories of methylation in the fetus and newborn. Furthermore, these trajectories are substantially modified by intrauterine exposure to sGC. These sGC-induced changes in DNA methylation remain into adulthood and are evident in the next generation. Furthermore, prenatal sGC exposure alters the expression of several genes encoding proteins that modulate the epigenetic state. Several of these changes are long lasting and are also present in the next generation. These data support the hypothesis that prenatal sGC exposure leads to broad changes in critical components of the epigenetic machinery and that these effects can pass to the next generation.     

Frequent switching of Polycomb repressive marks and DNA hypermethylation in the PC3 prostate cancer cell line

Epigenetic reprogramming is commonly observed in cancer, and is hypothesized to involve multiple mechanisms, including DNA methylation and Polycomb repressive complexes (PRCs). Here we devise a new experimental and analytical strategy using customized high-density tiling arrays to investigate coordinated patterns of gene expression, DNA methylation, and Polycomb marks which differentiate prostate cancer cells from their normal counterparts. Three major changes in the epigenomic landscape distinguish the two cell types. Developmentally significant genes containing CpG islands which are silenced by PRCs in the normal cells acquire DNA methylation silencing and lose their PRC marks (epigenetic switching). Because these genes are normally silent this switch does not cause de novo repression but might significantly reduce epigenetic plasticity. Two other groups of genes are silenced by either de novo DNA methylation without PRC occupancy (5mC reprogramming) or by de novo PRC occupancy without DNA methylation (PRC reprogramming). Our data suggest that the two silencing mechanisms act in parallel to reprogram the cancer epigenome and that DNA hypermethylation may replace Polycomb-based repression near key regulatory genes, possibly reducing their regulatory plasticity.     

Causal effects of the early caregiving environment on development of stress response systems in children

Disruptions in stress response system functioning are thought to be a central mechanism by which exposure to adverse early-life environments influences human development. Although early-life adversity results in hyperreactivity of the sympathetic nervous system (SNS) and hypothalamic–pituitary–adrenal (HPA) axis in rodents, evidence from human studies is inconsistent. We present results from the Bucharest Early Intervention Project examining whether randomized placement into a family caregiving environment alters development of the autonomic nervous system and HPA axis in children exposed to early-life deprivation associated with institutional rearing. Electrocardiogram, impedance cardiograph, and neuroendocrine data were collected during laboratory-based challenge tasks from children (mean age = 12.9 y) raised in deprived institutional settings in Romania randomized to a high-quality foster care intervention (n = 48) or to remain in care as usual (n = 43) and a sample of typically developing Romanian children (n = 47). Children who remained in institutional care exhibited significantly blunted SNS and HPA axis responses to psychosocial stress compared with children randomized to foster care, whose stress responses approximated those of typically developing children. Intervention effects were evident for cortisol and parasympathetic nervous system reactivity only among children placed in foster care before age 24 and 18 months, respectively, providing experimental evidence of a sensitive period in humans during which the environment is particularly likely to alter stress response system development. We provide evidence for a causal link between the early caregiving environment and stress response system reactivity in humans with effects that differ markedly from those observed in rodent models.Disruptions in stress response system functioning are thought to be a central mechanism by which exposure to adverse early-life environments influences human development. This idea is borne out in rodent models, where the effects of early-life adversity on the development of stress response systems have been well characterized. Exposure to early-life adversity—involving repeated and prolonged separation of a pup from its mother—results in hyperreactivity of the sympathetic nervous system (SNS) and the hypothalamic–pituitary–adrenal (HPA) axis in adolescence and adulthood and elevations in anxiety, fearful behaviors, and hypervigilance (1–4). Stress exposure in mature rodents is associated with immediate, but not lasting, changes in stress response systems (5, 6), suggesting the presence of an early sensitive period when exposure to adverse environments results in long-term changes in physiological stress response system functioning.A similar pattern of findings has been observed in some, but not all, studies of HPA axis development in nonhuman primates following early-life adversity. Rhesus and squirrel monkeys exposed to prolonged early-life maternal deprivation exhibit elevated basal levels of cortisol (7–9), enhanced glucocorticoid feedback sensitivity (10), and heightened cortisol reactivity to social stress in some studies (11, 12), but lower basal cortisol and reduced cortisol reactivity in others (9, 13, 14). The effect of maternal deprivation on SNS development in nonhuman primates has been studied infrequently.Investigations of early-life adversity and stress response system reactivity in humans have produced decidedly mixed findings. Some studies document hyperreactivity of the SNS and HPA axis following early-life adversity (15–19) and others observe blunted HPA axis reactivity (20–22) or discordance between SNS and HPA axis responses (23). Reconciling these inconsistencies has proved challenging for several reasons. First, there is considerable heterogeneity in the type, frequency, severity, and co-occurrence of early-life adversities in human studies, including both abuse and neglect (15, 18, 19, 21, 22), poverty (24–26), institutional rearing followed by international adoption (17, 20, 27, 28), or accumulation of multiple adversities, ranging from marital conflict to parental psychopathology (29–31). These exposures not only differ widely from each other, they also vary in their resemblance to the exposure used in animal studies: maternal deprivation. Lower morning cortisol and blunted cortisol reactivity are the most commonly reported patterns in studies of maternal deprivation related to neglect or institutional rearing following by international adoption (20, 28, 32), although elevated basal cortisol and cortisol reactivity have also been observed (17, 27). Second, existing human research has been unable to identify causal effects of the rearing environment on stress response system development. In animals, physiological hyperreactivity induced by exposure to early-life adversity can be ameliorated by placement in an enriched environment during puberty (33), indicating that the neurobiological consequences of early-life adversity may be reversed, at least in part, through improvements to the environment. Although physiological reactivity in humans can be altered in the short term by psychosocial interventions (34, 35), including in children exposed to maternal deprivation (36, 37), we are unaware of experimental research examining whether random assignment to a caregiving environment alters patterns of physiological reactivity later in development. Finally, although a sensitive period exists during which the environment has particularly strong influences on stress response system development in animals, studies that can rigorously identify such a period in humans are lacking.We present comprehensive data on autonomic nervous system (ANS) and HPA axis reactivity from the Bucharest Early Intervention Project (BEIP), the only randomized controlled trial of foster care as an alternative to institutional rearing for abandoned children, to address each of these challenges. First, the nature of early-life adversity in the BEIP closely parallels the type of adversity studied in the animal literature: psychosocial (including maternal) deprivation. Second, the experimental design of the BEIP allows us to identify causal effects of the caregiving environment on long-term development of the stress response system. Finally, the BEIP data are unique in having detailed information on the timing of exposure to adversity, which allows us to determine whether there is a sensitive period of stress response development in humans.     

Epigenetic changes associated with hyperglycaemia exposure in the longitudinal D.E.S.I.R. cohort

Aim- Understanding DNA methylation dynamics associated with progressive hyperglycaemia exposure could provide early diagnostic biomarkers and an avenue for delaying type 2 diabetes mellitus (T2DM). We aimed to identify DNA methylation changes during a 6-year period associated with early hyperglycaemia exposure using the longitudinal D.E.S.I.R. cohort.Methods- We selected individuals with progressive hyperglycaemia exposure based on T2DM diagnostic criteria: 27 with long-term exposure, 34 with short-term exposure and 34 normoglycaemic controls. DNA from blood at inclusion and at the 6-year visit was subjected to methylation analysis using 850K methylation-EPIC arrays. A linear mixed model was used to perform an epigenome-wide association study (EWAS) and identify methylated changes associated with hyperglycaemia exposure during a 6-year time-period.Results- We did not identify differentially methylated sites that reached false discovery rate (FDR)-significance in our cohort. Based on EWAS, we focused our analysis on methylation sites that had a constant effect during the 6 years across the hyperglycaemia groups compared to controls and found the most statistically significant site was the reported cg19693031 probe (TXNIP). We also performed an EWAS with HbA1c, using the inclusion and the 6-year methylation data and did not identify any FDR-significant CpGs.Conclusions- Our study reveals that DNA methylation changes are not robustly associated with hyperglycaemia exposure or HbA1c during a short-term period, however, our top loci indicate potential interest and should be replicated in larger cohorts.     

Differential methylation of genes in individuals exposed to maternal diabetes in utero

Aims/hypothesis

Individuals exposed to maternal diabetes in utero are more likely to develop metabolic and cardiovascular diseases later in life. This may be partially attributable to epigenetic regulation of gene expression. We performed an epigenome-wide association study to examine whether differential DNA methylation, a major source of epigenetic regulation, can be observed in offspring of mothers with type 2 diabetes during the pregnancy (OMD) compared with offspring of mothers with no diabetes during the pregnancy (OMND).

Methods

DNA methylation was measured in peripheral blood using the Illumina HumanMethylation450K BeadChip. A total of 423,311 CpG sites were analysed in 388 Pima Indian individuals, mean age at examination was 13.0 years, 187 of whom were OMD and 201 were OMND. Differences in methylation between OMD and OMND were assessed.

Results

Forty-eight differentially methylated CpG sites (with an empirical false discovery rate ≤0.05), mapping to 29 genes and ten intergenic regions, were identified. The gene with the strongest evidence was LHX3, in which six CpG sites were hypermethylated in OMD compared with OMND (p?≤?1.1?×?10^?5). Similarly, a CpG near PRDM16 was hypermethylated in OMD (1.1% higher, p?=?5.6?×?10^?7), where hypermethylation also predicted future diabetes risk (HR 2.12 per SD methylation increase, p?=?9.7?×?10^?5). Hypermethylation near AK3 and hypomethylation at PCDHGA4 and STC1 were associated with exposure to diabetes in utero (AK3: 2.5% higher, p?=?7.8?×?10^?6; PCDHGA4: 2.8% lower, p?=?3.0?×?10^?5; STC1: 2.9% lower, p?=?1.6?×?10^?5) and decreased insulin secretory function among offspring with normal glucose tolerance (AK3: 0.088 SD lower per SD of methylation increase, p?=?0.02; PCDHGA4: 0.08 lower SD per SD of methylation decrease, p?=?0.03; STC1: 0.072 SD lower per SD of methylation decrease, p?=?0.05). Seventeen CpG sites were also associated with BMI (p?≤?0.05). Pathway analysis of the genes with at least one differentially methylated CpG (p?<?0.005) showed enrichment for three relevant biological pathways.

Conclusions/interpretation

Intrauterine exposure to diabetes can affect methylation at multiple genomic sites. Methylation status at some of these sites can impair insulin secretion, increase body weight and increase risk of type 2 diabetes.