Environmental exposures, psychosocial stressors and nutrition are all potentially important influences that may impact health outcomes directly or via interactions with the genome or epigenome over generations. While there have been clear successes in large-scale human genetic studies in recent decades, there is still a substantial amount of missing heritability to be elucidated for complex childhood disorders. Mounting evidence, primarily in animals, suggests environmental exposures may generate or perpetuate altered health outcomes across one or more generations. One putative mechanism for these environmental health effects is via altered epigenetic regulation. This review highlights the current epidemiologic literature and supporting animal studies that describe intergenerational and transgenerational health effects of environmental exposures. Both maternal and paternal exposures and transmission patterns are considered, with attention paid to the attendant ethical, legal and social implications.

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Exploring the evidence for epigenetic regulation of environmental influences on child health across generations

OBJECTIVE To elucidate whether pre-eclampsia (PE) and the gestational age at onset of the disease (early- vs late-onset PE) have an impact on the risk of long-term maternal cardiovascular complications. METHODS MEDLINE, EMBASE and Scopus databases were searched until 15 April 2020 for studies evaluating the incidence of cardiovascular events in women with a history of PE, utilizing combinations of the relevant MeSH terms, keywords and word variants for 'pre-eclampsia', 'cardiovascular disease' and 'outcome'. Inclusion criteria were cohort or case-control design, inclusion of women with a diagnosis of PE at the time of the first pregnancy, and sufficient data to compare each outcome in women with a history of PE vs women with previous normal pregnancy and/or in women with a history of early- vs late-onset PE. The primary outcome was a composite score of maternal cardiovascular morbidity and mortality, including cardiovascular death, major cardiovascular and cerebrovascular events, hypertension, need for antihypertensive therapy, Type-2 diabetes mellitus, dyslipidemia and metabolic syndrome. Secondary outcomes were the individual components of the primary outcome analyzed separately. Data were combined using a random-effects generic inverse variance approach. MOOSE guidelines and the PRISMA statement were followed. RESULTS Seventy-three studies were included. Women with a history of PE, compared to those with previous normotensive pregnancy, had a higher risk of composite adverse cardiovascular outcome (odds ratio (OR), 2.05 (95% CI, 1.9-2.3)), cardiovascular death (OR, 2.18 (95% CI, 1.8-2.7)), major cardiovascular events (OR, 1.80 (95% CI, 1.6-2.0)), hypertension (OR, 3.93 (95% CI, 3.1-5.0)), need for antihypertensive medication (OR, 4.44 (95% CI, 2.4-8.2)), dyslipidemia (OR, 1.32 (95% CI, 1.3-1.4)), Type-2 diabetes (OR, 2.14 (95% CI, 1.5-3.0)), abnormal renal function (OR, 3.37 (95% CI, 2.3-5.0)) and metabolic syndrome (OR, 4.30 (95% CI, 2.6-7.1)). Importantly, the strength of the associations persisted when considering the interval (  10 years) from PE to the occurrence of these outcomes. When stratifying the analysis according to gestational age at onset of PE, women with previous early-onset PE, compared to those with previous late-onset PE, were at higher risk of composite adverse cardiovascular outcome (OR, 1.75 (95% CI, 1.0-3.0)), major cardiovascular events (OR, 5.63 (95% CI, 1.5-21.4)), hypertension (OR, 1.48 (95% CI, 1.3-1.7)), dyslipidemia (OR, 1.51 (95% CI, 1.3-1.8)), abnormal renal function (OR, 1.52 (95% CI, 1.1-2.2)) and metabolic syndrome (OR, 1.66 (95% CI, 1.1-2.5). CONCLUSIONS Both early- and late-onset PE represent risk factors for maternal adverse cardiovascular events later in life. Early-onset PE is associated with a higher burden of cardiovascular morbidity and mortality compared to late-onset PE. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Cardiovascular events following pregnancy complicated by pre-eclampsia with emphasis on comparison between early- and late-onset forms: systematic review and meta-analysis.

The associations of maternal hypertensive pregnancy disorders with offspring mental disorders remain unclear. We examined whether maternal hypertensive disorders and maximum blood pressure during pregnancy predict offspring childhood mental disorders, whether the associations are independent of maternal and paternal mental disorders and paternal hypertensive disorders, independent of or additive with maternal early pregnancy overweight/obesity and diabetes mellitus disorders, and mediated or moderated by preterm birth, small-for-gestational-age birth and neonatal intensive care unit admission. Our prospective study comprised 4743 mother-child dyads of Prediction and Prevention of Preeclampsia and Intrauterine Growth Restriction study. Women were recruited to the study in early pregnancy at Finnish maternity hospitals. Children were born 2006 to 2010 and followed-up until December 31, 2016, to ages 6.4 to 10.8 years. Hypertensive pregnancy disorders were identified from medical records, Medical Birth Register, and Care Register for Health Care. Systolic and diastolic blood pressure were measured at antenatal clinics and hospital visits. Mental disorder diagnoses were identified from Care Register for Health Care. Maternal gestational and chronic hypertension, preeclampsia and its severity increased offspring hazard of any childhood mental disorder. The associations of preeclampsia (hazard ratio=1.66 [95% CI, 1.14-2.42]) and severe preeclampsia (hazard ratio=2.01 [95% CI, 1.08-3.73]) were independent of all covariates. Maternal hypertensive and diabetes mellitus disorders and overweight/obesity also additively increased offspring hazard of mental disorders. Preterm and small-for-gestational-age births and neonatal intensive care unit admission partially mediated the effects of any and severe preeclampsia on offspring mental disorders. To conclude, maternal hypertensive pregnancy disorders carry adverse consequences for offspring mental health.

Maternal Hypertensive Pregnancy Disorders and Mental Disorders in Children

Worldwide, hypertension and chronic kidney disease (CKD) are highly prevalent disorders and are strong risk factors for cardiovascular disease and end-stage renal disease (ESRD). The developmental origins of health and disease (DOHAD) concept suggests that undesirable perinatal environmental conditions, such as malnutrition, contribute to disease development in adults. Among the known hypertension and CKD risk factors, DOHAD plays a potential role in determining susceptibility to the onset of these diseases in later adulthood. Since low birth weight (LBW) is a surrogate marker for adverse fetal environmental conditions, the high incidence of LBW in developing countries and its increasing incidence in most developed countries (attributed to multiple pregnancies and prepregnancy maternal factors, such as undernutrition, advanced maternal age, and smoking) is concerning. Thus, LBW is an important public health problem not only because of the associated infant mortality and morbidity but also because it is a risk factor for adult-onset hypertension/CKD. During their reproductive years, pregnant women who were born with LBWs have an increased risk of hypertensive disorders of pregnancy, which contribute to the risk of developing cardiovascular disease and ESRD. The offspring of LBW females are also likely to be LBW, which suggests that susceptibility to hypertension/CKD may reflect transgenerational inheritance. Therefore, there is global concern about the increasing prevalence of LBW-related diseases. This review summarizes the relevance of hypertension and CKD in conjunction with DOHAD and discusses recent studies that have examined the impact of the upward LBW trend on renal function and blood pressure.

Low birth weight trends: possible impacts on the prevalences of hypertension and chronic kidney disease.

Coronary heart disease (CHD) is a type of cardiovascular disease (CVD) that affects the coronary arteries, which provide oxygenated blood to the heart. It is a major cause of mortality worldwide. Various prediction methods have been developed to assess the likelihood of developing CHD, including those based on clinical features and genetic variation. Recent epigenome-wide studies have identified DNA methylation signatures associated with the development of CHD, indicating that DNA methylation may play a role in predicting future CHD. This narrative review summarises recent findings from DNA methylation studies of incident CHD (iCHD) events from epigenome-wide association studies (EWASs). The results suggest that DNA methylation signatures may identify new mechanisms involved in CHD progression and could prove a useful adjunct for the prediction of future CHD.

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DNA methylation signatures of incident coronary heart disease: findings from epigenome-wide association studies

Hypertensive disorders of pregnancy (HDP) are associated with low birth weight, shorter gestational age, and increased risk of maternal and offspring cardiovascular diseases later in life. The mechanisms involved are poorly understood, but epigenetic regulation of gene expression may play a part. We performed meta-analyses in the Pregnancy and Childhood Epigenetics Consortium to test the association between either maternal HDP (10 cohorts; n=5242 [cases=476]) or preeclampsia (3 cohorts; n=2219 [cases=135]) and epigenome-wide DNA methylation in cord blood using the Illumina HumanMethylation450 BeadChip. In models adjusted for confounders, and with Bonferroni correction, HDP and preeclampsia were associated with DNA methylation at 43 and 26 CpG sites, respectively. HDP was associated with higher methylation at 27 (63%) of the 43 sites, and across all 43 sites, the mean absolute difference in methylation was between 0.6% and 2.6%. Epigenome-wide associations of HDP with offspring DNA methylation were modestly consistent with the equivalent epigenome-wide associations of preeclampsia with offspring DNA methylation (R2=0.26). In longitudinal analyses conducted in 1 study (n=108 HDP cases; 550 controls), there were similar changes in DNA methylation in offspring of those with and without HDP up to adolescence. Pathway analysis suggested that genes located at/near HDP-associated sites may be involved in developmental, embryogenesis, or neurological pathways. HDP is associated with offspring DNA methylation with potential relevance to development.

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Dana Dabelea

Papers

Hypertensive Disorders of Pregnancy and DNA Methylation in Newborns Findings From the Pregnancy and Childhood Epigenetics Consortium