Vascular health years after a hypertensive disorder of pregnancy: The EPOCH study

BACKGROUND

Preeclampsia is associated with a two-fold increase in a woman's lifetime risk of developing atherosclerotic cardiovascular disease (ASCVD), but the reasons for this association are uncertain. The objective of this study was to examine the associations between vascular health and a hypertensive disorder of pregnancy among women ≥ 2 years postpartum.

METHODS

Pre-menopausal women with a history of either a hypertensive disorder of pregnancy (cases: preeclampsia or gestational hypertension) or a normotensive pregnancy (controls) were enrolled. Participants were assessed for standard ASCVD risk factors and underwent vascular testing, including measurements of blood pressure, endothelial function, and carotid artery ultrasound. The primary outcomes were blood pressure, ASCVD risk, reactive hyperemia index measured by EndoPAT and carotid intima-medial thickness. The secondary outcomes were augmentation index normalized to 75 beats per minute and pulse wave amplitude measured by EndoPAT, and carotid elastic modulus and carotid beta-stiffness measured by carotid ultrasound.

RESULTS

Participants had a mean age of 40.7 years and were 5.7 years since their last pregnancy. In bivariate analyses, cases (N = 68) were more likely than controls (N = 71) to have hypertension (18% vs 4%, P = .034), higher calculated ASCVD risk (0.6 vs 0.4, P = .02), higher blood pressures (systolic: 118.5 vs 111.6 mm Hg, P = .0004; diastolic: 75.2 vs 69.8 mm Hg, P = .0004), and higher augmentation index values (7.7 vs 2.3, P = .03). They did not, however, differ significantly in carotid intima-media thickness (0.5 vs 0.5, P = .29) or reactive hyperemia index (2.1 vs 2.1, P = .93), nor in pulse wave amplitude (416 vs 326, P = .11), carotid elastic modulus (445 vs 426, P = .36), or carotid beta stiffness (2.8 vs 2.8, P = .86).

CONCLUSION

Women with a prior hypertensive disorder of pregnancy had higher ASCVD risk and blood pressures several years postpartum, but did not have more endothelial dysfunction or subclinical atherosclerosis.

Reference ranges for third-trimester maternal cardiovascular function parameters measured in normotensive pregnant women using a non-invasive cardiac output monitor: A study based on data from the prospective PEACH cohort study

OBJECTIVE

We defined reference ranges for maternal cardiac output, systemic vascular resistance, and stroke volume measured in the third trimester of pregnancy using the Ultrasound Cardiac Output Monitor 1A.

DESIGN

Based on data from the prospective PEACH (PreEclampsia, Angiogenesis, Cardiac dysfunction and Hypertension) cohort study.

SETTING

Rigshospitalet and Hvidovre Hospital, Denmark.

SAMPLE

Normotensive pregnant women aged 18-45 years with singleton pregnancies, enrolled in the PEACH study in 2016-2018.

METHODS

We modelled cardiac output, systemic vascular resistance and stroke volume as a function of gestational age using multilevel linear models with fractional polynomials.

MAIN OUTCOME MEASURES

Unconditional and conditional reference ranges for cardiovascular parameters measured in gestational weeks 28-40.

RESULTS

Our study cohort included 405 healthy pregnant women who contributed 1210 cardiovascular function measurements for analysis. Maximum cardiac output and stroke volume values were measured in gestational weeks 30-32 and decreased over the third trimester, whereas systemic vascular resistance increased during the same period. We created reference ranges for eight combinations of maternal height, age and parity. We also created a simple calculator to allow for implementation of the reference ranges in clinical practice.

CONCLUSIONS

Our reference ranges allow the use of a bedside ultrasound device to non-invasively assess cardiac function in pregnancy and identify women at risk of complications. The unconditional ranges allow clinicians to evaluate isolated measurements and identify women needing follow-up. The conditional ranges incorporate information from previous measurements and improve monitoring over time.

Time trends in preeclampsia and gestational diabetes in Denmark and Alberta, Canada, 2005-2018-A population-based cohort study

INTRODUCTION

Preeclampsia and gestational diabetes mellitus share risk factors such as obesity and increased maternal age, which have become more prevalent in recent decades. We examined changes in the prevalence of preeclampsia and gestational diabetes between 2005 and 2018 in Denmark and Alberta, Canada, and investigated whether the observed trends can be explained by changes in maternal age, parity, multiple pregnancy, comorbidity, and body mass index (BMI) over time.

MATERIAL AND METHODS

This study was a register-based cohort study conducted using data from the Danish National Health Registers and the provincial health registers of Alberta, Canada. We included in the study cohort all pregnancies in 2005-2018 resulting in live-born infants and used binomial regression to estimate mean annual increases in the prevalence of preeclampsia and gestational diabetes in the two populations across the study period, adjusted for maternal characteristics.

RESULTS

The study cohorts included 846 127 (Denmark) and 706 728 (Alberta) pregnancies. The prevalence of preeclampsia increased over the study period in Denmark (2.5% to 2.9%) and Alberta (1.7% to 2.5%), with mean annual increases of 0.03 (95% confidence interval [CI] 0.02-0.04) and 0.06 (95% CI 0.05-0.07) percentage points, respectively. The prevalence of gestational diabetes also increased in Denmark (1.9% to 4.6%) and Alberta (3.9% to 9.2%), with average annual increases of 0.20 (95% CI 0.19-0.21) and 0.44 (95% CI 0.42-0.45) percentage points. Changes in the distributions of maternal age and BMI contributed to increases in the prevalence of both conditions but could not explain them entirely.

CONCLUSIONS

The prevalence of both preeclampsia and gestational diabetes increased significantly from 2005 to 2018, which portends future increases in chronic disease rates among affected women. Increasing demand for long-term follow up and care will amplify the existing pressure on healthcare systems.

Normative Echocardiographic Left Ventricular Parameters and Reference Intervals in Infants

BACKGROUND

In pediatric echocardiography, reference intervals are required to distinguish normal variation from pathology. Left ventricular (LV) parameters are particularly important predictors of clinical outcome. However, data from healthy newborns are limited, and current reference intervals provide an inadequate approximation of normal reference ranges.

OBJECTIVES

Normative reference intervals and z-scores for 2-dimensional echocardiographic measurements of LV structure and function based on a large group of healthy newborns were developed.

METHODS

The study population included 13,454 healthy newborns from the Copenhagen Baby Heart Study who were born at term to healthy mothers, had an echocardiogram performed within 30 days of birth, and did not have congenital heart disease. To develop normative reference intervals, this study modeled 10 LV parameters as a function of body surface area through joint modeling of 4 statistical components.

RESULTS

Infants in the study population (48.5% were female) had a median body surface area of 0.23 m² (IQR: 0.22-0.25 m²) and median age of 12.0 days (IQR: 8.0-15.0 days) at examination. All normative reference intervals performed well in both sexes without stratification on infant sex. In contrast, creation of separate reference models for infants examined at <7 days of age and those examined at 7-30 days of age was necessary to optimize the performance of the reference intervals.

CONCLUSIONS

This study provides normative reference intervals and z-scores for 10 clinical, widely used echocardiographic measures of LV structure and function based on a large cohort of newborns. These results provide highly needed reference material for clinical application by pediatric cardiologists.

Association between preeclampsia in daughters and risk of cardiovascular disease in parents

Preeclampsia and cardiovascular disease (CVD) might share heritable underlying mechanisms. We investigated whether preeclampsia in daughters is associated with CVD in parents. In a register-based cohort study, we used Cox regression to compare rates of CVD (ischemic heart disease, ischemic stroke, myocardial infarction) in parents with ≥ 1 daughters who had preeclampsia and parents whose daughters did not have preeclampsia in Denmark, 1978-2018. Our cohort included 1,299,310 parents, of whom 87,251 had ≥ 1 daughters with preeclampsia and 272,936 developed CVD during 20,252,351 years of follow-up (incidence rate 135/10,000 person-years). Parents with one daughter who had preeclampsia were 1.19 times as likely as parents of daughters without preeclampsia to develop CVD at age < 55 years (hazard ratio [HR] 1.19, 95% confidence interval [CI] 1.13-1.25). Having ≥ 2 daughters who had preeclampsia yielded an HR of 1.88 (95% CI 1.39-2.53). The corresponding HRs for CVD at ≥ 55 years of age were 1.13 (95% CI 1.12-1.15) and 1.27 (95% CI 1.16-1.38). Patterns of association were similar for all CVD subtypes. Effect magnitudes did not differ for mothers and fathers (p = 0.52). Analyses by timing of preeclampsia onset in daughters suggested a tendency toward stronger associations with earlier preeclampsia onset, particularly in parents < 55 years. Preeclampsia in daughters was associated with increased risks of CVD in parents. Increasing strength of association with increasing number of affected daughters, equally strong associations for mothers and fathers, and stronger associations for CVD occurring before age 55 years suggest that preeclampsia and CVD share common heritable mechanisms.

Risk and trajectory of premature ischaemic cardiovascular disease in women with a history of pre-eclampsia: a nationwide register-based study

AIMS

Pre-eclampsia increases women's lifetime risk of cardiovascular disease (CVD). Little is known about the trajectory of CVD after pre-eclampsia, limiting the usefulness of this knowledge for informing screening, prevention, and interventions. We investigated when the risk of CVD increases after pre-eclampsia and how the risk changes over time since pregnancy.

METHODS AND RESULTS

This register-based study included 1 157 666 women with >1 pregnancy between 1978 and 2017. Cumulative incidences of acute myocardial infarction (AMI) and ischaemic stroke were estimated, as well as hazard ratios (HRs) by attained age and time since delivery. Up to 2% [95% confidence interval (CI): 1.46-2.82%] of women with pre-eclampsia in their first pregnancy had an AMI or stroke within two decades of delivery, compared with up to 1.2% (95% CI: 1.08-1.30%) of pre-eclampsia-free women; differences in cumulative incidences were evident 7 years after delivery. Ten years after delivery, women with pre-eclampsia had four- and three-fold higher rates of AMI (HR = 4.16, 95% CI: 3.16-5.49) and stroke (HR = 2.59, 95% CI 2.04-3.28) than women without pre-eclampsia; rates remained doubled >20 years later. Women with pre-eclampsia aged 30-39 years had five-fold and three-fold higher rates of AMI (HR = 4.88, 95% CI 3.55-6.71) and stroke (HR = 2.56, 95% CI 1.95-3.36) than women of similar age without pre-eclampsia.

CONCLUSIONS

Women with a history of pre-eclampsia have high rates of AMI and stroke at early ages and within a decade after delivery. The findings suggest that pre-eclampsia history could be useful in identifying women at increased risk of CVD and that targeted interventions should be initiated soon after delivery.

Risk of Congenital Heart Defects in Offspring of Affected Mothers and Fathers

Background:

Smaller studies have reported a higher offspring risk of congenital heart defects (CHDs) for mothers with CHDs than for fathers with CHDs. In a large population-based study, we investigated whether offspring risk of CHD differed for mothers and fathers with CHDs.

Methods:

All people born in Denmark, 1977 to 2011, with at least 1 registered parent, were included in our cohort (n=2 341 061). Parent-child recurrence of CHDs was evaluated using risk ratios (RRs) comparing risks of CHDs in individuals with and without a parent with a CHD, estimated using log-linear binomial regression.

Results:

The RRs for any CHD in offspring were 5.39 (95% CI, 4.88–5.96) for mothers and 3.04 (95% CI, 2.59–3.57) for fathers affected with any CHD; the ratio of RRs for mothers versus fathers was 1.82 ( P <0.0001). Recurrence RRs for the same cardiac phenotype in parent and offspring were significantly stronger for mothers than for fathers for conotruncal defects (ratio of RRs, 4.98), left ventricular outlet tract obstruction (ratio of RRs, 4.98), and ventricular septal defects (ratio of RRs, 2.51) but not for atrioventricular septal defects (ratio of RRs, 1.06). Birth rates among people with CHDs, relative to the general population, were 18% higher for women than for men, regardless of parental cardiac phenotype.

Conclusions:

Recurrence risks of CHDs were significantly greater in the offspring of affected women than in the offspring of affected men. The excess maternal recurrence risks could not be explained by the slightly higher birth rates in women with CHDs.

The Impact of Maternal Age on the Neonatal Electrocardiogram

BACKGROUND

Previous studies have suggested an increased prevalence of congenital heart disease among children born to women aged ≥35 years. In recent decades, the mother's age at childbirth has increased dramatically in industrialized countries. It has not been investigated if increasing maternal age affects the neonatal cardiac electrical system.

METHODS

The Copenhagen Baby Heart Study is a prospective general population study that performed cardiac evaluation in newborns. Electrocardiograms were analyzed with a computerized algorithm.

RESULTS

We included 16,518 newborns with normal echocardiograms (median age 11 days; range 0-30 days; 52% boys). Median maternal age at delivery was 31 years; 790 newborns were born to mothers aged between 16 and 24 years, 11,403 between 25 and 34 years, 4,279 between 35 and 44 years, and 46 newborns had mothers aged between 45 and 54 years. The QRS axis and maximum R-wave amplitude in V1 (R-V1) differed across the four maternal age groups (both p < 0.01), with absolute differences of 3.5% (114 vs. 110°) and 12% (1,152 vs. 1,015 µV), respectively, between newborns with the youngest and oldest mothers. Associations between maternal age and the QRS axis and R-V1 remained significant after multifactorial adjustment. Heart rate, PR interval, QRS duration, uncorrected QT interval, QTcBazett, and maximum amplitudes of S-V1, R-V6, and S-V6 were not associated with maternal age (all p > 0.05).

CONCLUSION

We observed a significant association between maternal age and the neonatal QRS axis and R-V1. However, the absolute differences were relatively small and maternal age is unlikely to have a clinically significant effect on the neonatal cardiac electrical system.

Genome-wide association study identifies 48 common genetic variants associated with handedness

Handedness has been extensively studied because of its relationship with language and the over-representation of left-handers in some neurodevelopmental disorders. Using data from the UK Biobank, 23andMe and the International Handedness Consortium, we conducted a genome-wide association meta-analysis of handedness (N = 1,766,671). We found 41 loci associated (P < 5 × 10-8) with left-handedness and 7 associated with ambidexterity. Tissue-enrichment analysis implicated the CNS in the aetiology of handedness. Pathways including regulation of microtubules and brain morphology were also highlighted. We found suggestive positive genetic correlations between left-handedness and neuropsychiatric traits, including schizophrenia and bipolar disorder. Furthermore, the genetic correlation between left-handedness and ambidexterity is low (rG = 0.26), which implies that these traits are largely influenced by different genetic mechanisms. Our findings suggest that handedness is highly polygenic and that the genetic variants that predispose to left-handedness may underlie part of the association with some psychiatric disorders.

P3441Impact of maternal preeclampsia on left ventricular structure and function in the newborn heart

Background

Maternal preeclampsia (PE) has been associated with an increased risk of a variety of congenital heart defects in the infant. Whether PE also confers an increased risk of subtle structural and functional cardiac deficits is unknown.

Purpose

We investigated whether left ventricular dimensions and systolic function differed among infants of mothers with PE, compared to infants born after uncomplicated pregnancies.

Method

Systematic transthoracic echocardiography (TTE) was performed in neonates included in a population-based study in the period 2016–2018 (n=25,000). TTE was preferably performed within 14 days of birth. Left ventricular (LV) posterior wall end-diastolic thickness (LVPWd), interventricular septum end-diastole thickness (IVSd), LV internal diameter in end-diastole and end-systole (LVIDd and LVIDs), LV ejection fraction (LVEF) and fractional shortening (FS) were assessed. Information on maternal PE (ICD-10 codes DO140–142 and DO159) was retrieved from an obstetric database. Using linear regression in a sample of echocardiograms, we compared the LV structure and function adjusted for maternal age; gestational age; sex; weight and length.

Results

In total, 447 infants were exposed to PE, and 7,178 were born to uncomplicated pregnancies (Table). In infants of PE mothers, we found significantly larger LVPWd and IVSd (0.18 mm, 95% CI [0.14; 0.22], p<0.001 and 0.06 mm, 95% CI [0.02; 0.10], p=0.001, resp.) and LVIDd as LVIDs were significantly smaller (−0.15 mm, 95% CI [−0.29; −0.01], p=0.032 and −0.16 mm 95% CI [−0.28; −0.04], p=0.009, resp.) compared to infants of non-PE mothers. We found no differences in systolic function.

LV measures in PE and non-PE infants Parameter Infants of PE mothers, Infants of non-PE mothers, p-value Estimate* [95% CI] p-value mean [± SD] (n=447) mean [± SD] (n=7,178) Left Ventricular Posterior Wall in end-Diastole, LVPWd (mm) 2.20 [±0.58] 2.07 [±0.40] <0.001 0.18 [0.14; 0.22] <0.001 Interventricular Septum in end-Diastole, IVSd (mm) 2.53 [±0.52] 2.55 [±0.41] 0.562 0.06 [0.02; 0.10] 0.001 Left Ventricular Internal Diameter in end-Diastole, LVIDd (mm) 19.35 [±2.00] 20.10 [±1.41] <0.001 −0.15 [−0.29; −0.01] 0.032 Left Ventricular Internal Diameter in end-Diastole, LVIDs (mm) 13.13 [±1.43] 13.65 [±1.79] <0.001 −0.16 [−0.28; −0.04] 0.009 Fractional Shortening, FS (%) 32.10 [±4.07] 32.11 [±3.86] 0.937 0.26 [−0.11; 0.63] 0.168 Left Ventricular Ejection Fraction, LVEF (%) 63.19 [±5.61] 63.09 [±5.30] 0.690 0.34 [−0.17; 0.85] 0.192 *Adjusted for maternal age; gestational age; sex; weight and length.

Conclusion

In the largest population-based group of neonates to date, we showed that infants born to PE mothers compared to infants of non-PE mothers had significantly thicker left ventricular myocardium, and reduced left ventricular volumes. However, PE was not associated with altered systolic function. Our results might reflect an adaption of the fetal heart to the increased resistance in the placental arteries in PE mothers, and a secondary increased left ventricular afterload.

Acknowledgement/Funding

Danish Heart Association, Danish Children's Heart Foundation, Candy's Found., Toyota Found., Herlev-Gentofte Hospital Research Found., Lundbeck Found.

Variants in the fetal genome near pro-inflammatory cytokine genes on 2q13 associate with gestational duration

The duration of pregnancy is influenced by fetal and maternal genetic and non-genetic factors. Here we report a fetal genome-wide association meta-analysis of gestational duration, and early preterm, preterm, and postterm birth in 84,689 infants. One locus on chromosome 2q13 is associated with gestational duration; the association is replicated in 9,291 additional infants (combined P = 3.96 × 10⁻¹⁴). Analysis of 15,588 mother-child pairs shows that the association is driven by fetal rather than maternal genotype. Functional experiments show that the lead SNP, rs7594852, alters the binding of the HIC1 transcriptional repressor. Genes at the locus include several interleukin 1 family members with roles in pro-inflammatory pathways that are central to the process of parturition. Further understanding of the underlying mechanisms will be of great public health importance, since giving birth either before or after the window of term gestation is associated with increased morbidity and mortality.

Gestational duration depends on both maternal and fetal genetic influences. Here, the authors perform a fetal genome-wide association meta-analysis and find that a locus on 2q13 is associated with pregnancy duration and further show that the lead SNP rs7594852 changes the binding properties of transcriptional repressor HIC1.

Genome-wide meta-analysis identifies BARX1 and EML4-MTA3 as new loci associated with infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is a disorder of young infants with a population incidence of ∼2/1000 live births, caused by hypertrophy of the pyloric sphincter smooth muscle. Reported genetic loci associated with IHPS explain only a minor proportion of IHPS risk. To identify new risk loci, we carried out a genome-wide meta-analysis on 1395 surgery-confirmed cases and 4438 controls, with replication in a set of 2427 cases and 2524 controls. We identified and replicated six independent genomic loci associated with IHPS risk at genome wide significance (P < 5 × 10-8), including novel associations with two single nucleotide polymorphisms (SNPs). One of these SNPs, rs6736913 [odds ratio (OR) = 2.32; P = 3.0 × 10-15], is a low frequency missense variant in EML4 at 2p21. The second SNP, rs1933683 (OR = 1.34; P = 3.1 × 10-9) is 1 kb downstream of BARX1 at 9q22.32, an essential gene for stomach formation in embryogenesis. Using the genome-wide complex trait analysis method, we estimated the IHPS SNP heritability to be 30%, and using the linkage disequilibrium score regression method, we found support for a previously reported genetic correlation of IHPS with lipid metabolism. By combining the largest collection of IHPS cases to date (3822 cases), with results generalized across populations of different ancestry, we elucidate novel mechanistic avenues of IHPS disease architecture.

Pregnancy loss and risk of later dementia: A nationwide cohort study, Denmark, 1977-2017

Introduction

Pregnancy losses may be associated with increased risks of dementia.

Methods

We conducted a register-based cohort study in 1,243,957 women with ≥1 pregnancy in Denmark in the period 1977–2015. Using Cox regression, we estimated hazard ratios (HRs) comparing risks of dementia in women with and without pregnancy losses.

Results

During 21,672,433 person-years of follow-up, 261,279 women experienced a pregnancy loss, and 2188 women were diagnosed with dementia. Stillbirth was associated with an 86% increased risk of dementia overall (HR 1.86, 95% confidence interval [CI] 1.28–2.71). By contrast, miscarriage was not associated with later risk of dementia overall (single miscarriage, HR 0.99, 95% CI 0.87–1.12; recurrent miscarriages, HR 1.06, 95% CI 0.84–1.35). Adjustment for cardiovascular disease, hypertension, and diabetes did not meaningfully alter the association magnitudes.

Discussion

Stillbirth and dementia may share underlying mechanisms, suggesting that a history of stillbirth should be considered when assessing dementia risk in women.

Pre-eclampsia and risk of later kidney disease: nationwide cohort study

OBJECTIVE

To investigate associations between pre-eclampsia and later risk of kidney disease.

DESIGN

Nationwide register based cohort study.

SETTING

Denmark.

POPULATION

All women with at least one pregnancy lasting at least 20 weeks between 1978 and 2015.

MAIN OUTCOME MEASURE

Hazard ratios comparing rates of kidney disease between women with and without a history of pre-eclampsia, stratified by gestational age at delivery and estimated using Cox regression.

RESULTS

The cohort consisted of 1 072 330 women followed for 19 994 470 person years (average 18.6 years/woman). Compared with women with no previous pre-eclampsia, those with a history of pre-eclampsia were more likely to develop chronic renal conditions: hazard ratio 3.93 (95% confidence interval 2.90 to 5.33, for early preterm pre-eclampsia (delivery <34 weeks); 2.81 (2.13 to 3.71) for late preterm pre-eclampsia (delivery 34-36 weeks); 2.27 (2.02 to 2.55) for term pre-eclampsia (delivery ≥37 weeks). In particular, strong associations were observed for chronic kidney disease, hypertensive kidney disease, and glomerular/proteinuric disease. Adjustment for cardiovascular disease and hypertension only partially attenuated the observed associations. Stratifying the analyses on time since pregnancy showed that associations between pre-eclampsia and chronic kidney disease and glomerular/proteinuric disease were much stronger within five years of the latest pregnancy (hazard ratio 6.11 (3.84 to 9.72) and 4.77 (3.88 to 5.86), respectively) than five years or longer after the latest pregnancy (2.06 (1.69 to 2.50) and 1.50 (1.19 to 1.88). By contrast, associations between pre-eclampsia and acute renal conditions were modest.

CONCLUSION

s Pre-eclampsia, particularly early preterm pre-eclampsia, was strongly associated with several chronic renal disorders later in life. More research is needed to determine which women are most likely to develop kidney disease after pre-eclampsia, what mechanisms underlie the association, and what clinical follow-up and interventions (and in what timeframe post-pregnancy) would be most appropriate and effective.

Hypertensive disorders of pregnancy and peripartum cardiomyopathy: A nationwide cohort study

Background

Peripartum cardiomyopathy (PPCM) is a serious cardiac disorder occurring late in pregnancy or early in the postpartum period. We examined associations between hypertensive disorders of pregnancy (HDP: preeclampsia and gestational hypertension) and PPCM, accounting for other pregnancy-related risk factors for PPCM.

Methods

Using nationwide Danish register data, we constructed a cohort of all women with ≥1 live birth or stillbirth in Denmark between 1978 and 2012. Using log-linear binomial regression and generalized estimating equations, we estimated risk ratios (RRs) for PPCM associated with HDP of varying severity.

Results

In a cohort of 1,088,063 women with 2,078,822 eligible pregnancies, 126 women developed PPCM (39 in connection with an HDP-complicated pregnancy). The risks of PPCM were significantly higher in women with HDP-complicated pregnancies than in women with normotensive pregnancies (severe preeclampsia, RR 21.2, 95% confidence interval [CI] 12.0–37.4; moderate preeclampsia, RR 10.2, 95% CI 6.18–16.9; gestational hypertension, RR 5.16, 95% CI 2.11–12.6). The RRs for moderate preeclampsia and gestational hypertension were not significantly different from one another (p = 0.18); the RR for severe preeclampsia was significantly different from the RR for moderate preeclampsia and gestational hypertension combined (p = 0.02).

Conclusions

Although 70% of PPCM occurred in women with normotensive pregnancies, HDPs were associated with substantial increases in PPCM risk that depended on HDP severity. The heart’s capacity to adapt to a normal pregnancy may be exceeded in some women already susceptible to cardiac insult, contributing to PPCM. HDPs, severe preeclampsia in particular, probably represent an additional cardiac stressor during pregnancy.

Pre-eclampsia and risk of dementia later in life: nationwide cohort study

OBJECTIVE

To explore associations between pre-eclampsia and later dementia, overall and by dementia subtype and timing of onset.

DESIGN

Nationwide register based cohort study.

SETTING

Denmark.

POPULATION

All women with at least one live birth or stillbirth between 1978 and 2015.

MAIN OUTCOME MEASURE

Hazard ratios comparing dementia rates among women with and without a history of pre-eclampsia, estimated using Cox regression.

RESULTS

The cohort consisted of 1 178 005 women with 20 352 695 person years of follow-up. Women with a history of pre-eclampsia had more than three times the risk of vascular dementia (hazard ratio 3.46, 95% confidence interval 1.97 to 6.10) later in life, compared with women with no history of pre-eclampsia. The association with vascular dementia seemed to be stronger for late onset disease (hazard ratio 6.53, 2.82 to 15.1) than for early onset disease (2.32, 1.06 to 5.06) (P=0.08). Adjustment for diabetes, hypertension, and cardiovascular disease attenuated the hazard ratios only moderately; sensitivity analyses suggested that body mass index was unlikely to explain the association with vascular dementia. In contrast, only modest associations were observed for Alzheimer's disease (hazard ratio 1.45, 1.05 to 1.99) and other/unspecified dementia (1.40, 1.08 to 1.83).

CONCLUSIONS

Pre-eclampsia was associated with an increased risk of dementia, particularly vascular dementia. Cardiovascular disease, hypertension, and diabetes were unlikely to mediate the associations substantially, suggesting that pre-eclampsia and vascular dementia may share underlying mechanisms or susceptibility pathways. Asking about a history of pre-eclampsia could help physicians to identify women who might benefit from screening for early signs of disease, allowing for early clinical intervention.

Familial aggregation of tonsillectomy in early childhood and adolescence

Background

The tonsils are immunological gatekeepers against pathogens. Immunological response to tonsillitis may vary clinically from no enlargement of the tonsils to nearly obstructive conditions. In this investigation, we studied the familial aggregation of tonsillectomy, as an indicator of the extent to which tonsillar immune responses to infections might be genetically controlled.

Methods

Data on kinship relations and vital status from the Danish Civil Registration System were used to establish a cohort of Danes with relatives born since 1977. Tonsillectomies in all hospitals and clinics from 1977 to 2013 were identified in national registers together with the indication for tonsillectomy. Rate ratios (RRs) for tonsillectomy >1 year after tonsillectomy in specific types of relatives (first to fourth degree) were estimated in Poisson regression models with adjustment for calendar period, sex, age, and total number of specified relatives.

Results

A cohort of 2.4 million persons was followed for 44,100,697 million person-years (mean 18.4 years/person), and included 148,190 tonsillectomies. RRs of tonsillectomy were consistently higher when the relatedness and the number of tonsillectomized relatives were higher. RRs were similar in boys and girls, but were larger in early childhood. Additional analyses suggested that this relatively higher RR at younger ages was due to a larger influence of shared environment at younger ages, whereas the genetic influence was similar at all ages. Results were similar for tonsillectomies performed strictly due to tonsillitis.

Conclusions

Genetic factors appear to predispose to severe tonsillitis underlying tonsillectomies, regardless of age and sex. Further studies are needed to understand how genes regulate the tonsils' immune response against infections.

Strabismus Incidence in a Danish Population-Based Cohort of Children

Importance

To our knowledge, there have been few population-based studies of strabismus incidence conducted. Our population-based study provides valuable data for health services planning and identifying research needs.

Objective

To determine the incidence and age distribution of strabismus, overall and by subtype, among children 7 years or younger.

Design, Setting, and Participants

This population-based cohort study was conducted with data from 96 842 children enrolled in the Danish National Birth Cohort.

Main Outcomes and Measures

Age-specific incidence and cumulative incidence and median age at the detection of strabismus, overall and by subtype.

Results

The study cohort included 96 842 children born between 1996 and 2008 who are predominantly Caucasian and is composed of approximately 30% of births in Denmark, with a boy-girl ratio of 51:49. Overall, 1309 cases of strabismus were identified in the cohort. We found an overall cumulative strabismus incidence of 2.56% (95% CI, 2.42-2.69) at 7 years. The overall incidence was similar among boys and girls. Two hundred sixteen participants (16.5%) (95% CI, 14.5-18.6) had congenital esotropia, 177 (13.5%) (95% CI, 11.7-15.5) had fully accommodative esotropia, 252 (19.3%) (95% CI, 17.1-21.5) had partially accommodative esotropia, and 181 (13.8%) (95% CI, 12.0-15.8) had exotropia. The esotropia:exotropia ratio was 5.4:1 (95% CI, 3.4:1 to 7.5:1). Age-specific incidence curves for congenital esotropia, fully accommodative esotropia, partially accommodative esotropia, and all exotropia revealed interactions between strabismus subtype and age, suggesting that the different subtypes had different age-specific patterns of incidence (P < .001 for all comparisons between pairs of curves). The median age at detection for the 4 subtypes was 0, 32.0, 26.1, and 16.6 months, respectively.

Conclusions and Relevance

In a national, population-based cohort study, we found a cumulative incidence of strabismus consistent with those reported in smaller European and American cohorts, but a somewhat higher esotropia:exotropia ratio than those that, to our knowledge, are typically reported by English and American studies. Patterns of incidence by age differed for different strabismus subtypes, indicating differences in age at onset and thereby implying differences in the underlying etiology.

Genetic Associations with Gestational Duration and Spontaneous Preterm Birth

BACKGROUND

Despite evidence that genetic factors contribute to the duration of gestation and the risk of preterm birth, robust associations with genetic variants have not been identified. We used large data sets that included the gestational duration to determine possible genetic associations.

METHODS

We performed a genomewide association study in a discovery set of samples obtained from 43,568 women of European ancestry using gestational duration as a continuous trait and term or preterm (<37 weeks) birth as a dichotomous outcome. We used samples from three Nordic data sets (involving a total of 8643 women) to test for replication of genomic loci that had significant genomewide association (P<5.0×10^-8) or an association with suggestive significance (P<1.0×10^-6) in the discovery set.

RESULTS

In the discovery and replication data sets, four loci (EBF1, EEFSEC, AGTR2, and WNT4) were significantly associated with gestational duration. Functional analysis showed that an implicated variant in WNT4 alters the binding of the estrogen receptor. The association between variants in ADCY5 and RAP2C and gestational duration had suggestive significance in the discovery set and significant evidence of association in the replication sets; these variants also showed genomewide significance in a joint analysis. Common variants in EBF1, EEFSEC, and AGTR2 showed association with preterm birth with genomewide significance. An analysis of mother-infant dyads suggested that these variants act at the level of the maternal genome.

CONCLUSIONS

In this genomewide association study, we found that variants at the EBF1, EEFSEC, AGTR2, WNT4, ADCY5, and RAP2C loci were associated with gestational duration and variants at the EBF1, EEFSEC, and AGTR2 loci with preterm birth. Previously established roles of these genes in uterine development, maternal nutrition, and vascular control support their mechanistic involvement. (Funded by the March of Dimes and others.).

Risk of post-pregnancy hypertension in women with a history of hypertensive disorders of pregnancy: nationwide cohort study

Objectives To determine how soon after delivery the risk of post-pregnancy hypertension increases in women with hypertensive disorders of pregnancy and how the risk evolves over time.Design Nationwide register based cohort study.Setting Denmark.Populations 482 972 primiparous women with a first live birth or stillbirth between 1995 and 2012 (cumulative incidence analyses), and 1 025 118 women with at least one live birth or stillbirth between 1978 and 2012 (Cox regression analyses).Main outcome measures 10 year cumulative incidences of post-pregnancy hypertension requiring treatment with prescription drugs, and hazard ratios estimated using Cox regression.Results Of women with a hypertensive disorder of pregnancy in a first pregnancy in their 20s, 14% developed hypertension in the first decade post partum, compared with 4% of women with normotensive first pregnancies in their 20s. The corresponding percentages for women with a first pregnancy in their 40s were 32% and 11%, respectively. In the year after delivery, women with a hypertensive disorder of pregnancy had 12-fold to 25-fold higher rates of hypertension than did women with a normotensive pregnancy. Rates in women with a hypertensive disorder of pregnancy were threefold to 10-fold higher 1-10 years post partum and remained twice as high even 20 or more years later.Conclusions The risk of hypertension associated with hypertensive disorders of pregnancy is high immediately after an affected pregnancy and persists for more than 20 years. Up to one third of women with a hypertensive disorder of pregnancy may develop hypertension within a decade of an affected pregnancy, indicating that cardiovascular disease prevention in these women should include blood pressure monitoring initiated soon after pregnancy.

Correction: The Influence of Age and Sex on Genetic Associations with Adult Body Size and Shape: A Large-Scale Genome-Wide Interaction Study

[This corrects the article DOI: 10.1371/journal.pgen.1005378.].

Prepregnancy Diabetes and Offspring Risk of Congenital Heart Disease: A Nationwide Cohort Study

BACKGROUND

Maternal diabetes mellitus is associated with an increased risk of offspring congenital heart defects (CHD); however, the causal mechanism is poorly understood. We further investigated this association in a Danish nationwide cohort.

METHODS AND RESULTS

In a national cohort study, we identified 2 025 727 persons born from 1978 to 2011; among them were 7296 (0.36%) persons exposed to maternal pregestational diabetes mellitus. Pregestational diabetes mellitus was identified by using the National Patient Register and individual-level information on all prescriptions filled in Danish pharmacies. Persons with CHD (n=16 325) were assigned to embryologically related cardiac phenotypes. The CHD prevalence in the offspring of mothers with pregestational diabetes mellitus was 318 per 10 000 live births (n=232) in comparison with a baseline risk of 80 per 10 000; the adjusted relative risk for CHD was 4.00 (95% confidence interval, 3.51-4.53). The association was not modified by year of birth, maternal age at diabetes onset, or diabetes duration, and CHD risks associated with type 1 (insulin-dependent) and type 2 (insulin-independent) diabetes mellitus did not differ significantly. Persons born to women with previous acute diabetes complications had a higher CHD risk than those exposed to maternal diabetes mellitus without complications (relative risk, 7.62; 95% confidence interval, 5.23-10.6, and relative risk, 3.49; 95% confidence interval, 2.91-4.13, respectively; P=0.0004). All specific CHD phenotypes were associated with maternal pregestational diabetes mellitus (relative risk range, 2.74-13.8).

CONCLUSIONS

The profoundly increased CHD risk conferred by maternal pregestational diabetes mellitus neither changed over time nor differed by diabetes subtype. The association with acute pregestational diabetes complications was particularly strong, suggesting a role for glucose in the causal pathway.

Association Between Hypertensive Disorders of Pregnancy and Later Risk of Cardiomyopathy

IMPORTANCE

Women with hypertensive disorders of pregnancy, preeclampsia in particular, have an increased risk of cardiomyopathy during the peripartum period. Whether hypertensive disorders of pregnancy are also associated with cardiomyopathy later in life is unknown.

OBJECTIVE

To determine whether hypertensive disorders of pregnancy are associated with cardiomyopathy beyond the peripartum period.

DESIGN, SETTING, AND PARTICIPANTS

Nationwide register-based cohort study using Cox regression to compare rates of cardiomyopathy in women with and without a history of hypertensive disorders of pregnancy in a cohort of 1,075,763 women with at least 1 pregnancy ending in live birth or stillbirth in Denmark, 1978-2012, with follow-up through December 31, 2012.

EXPOSURES

A hypertensive disorder of pregnancy (severe or moderate preeclampsia or gestational hypertension) registered in the National Patient Register.

MAIN OUTCOMES AND MEASURES

Cardiomyopathy more than 5 months after delivery (outside the peripartum period) up to 34 years 7 months.

RESULT

The women in the primary cohort had 2,067,633 eligible pregnancies during the study period, 76,108 of which were complicated by a hypertensive disorder of pregnancy. During follow-up, 1577 women (mean age, 48.5 years at cardiomyopathy diagnosis; 2.6% with multiple pregnancies) developed cardiomyopathy. Compared with women with normotensive pregnancies (18,211,603 person-years of follow-up; n = 1408 cardiomyopathy events, 7.7/100,000 person-years [95% CI, 7.3-8.2]), women with a history of hypertensive disorders of pregnancy had significantly increased rates of cardiomyopathy (in 173,062 person-years of follow-up among women with severe preeclampsia, n = 27 cardiomyopathy events; 15.6/100,000 person-years [95% CI, 10.7-22.7]; adjusted hazard ratio [HR], 2.20 [95% CI, 1.50-3.23]; in 697,447 person-years of follow-up among women with moderate preeclampsia, n = 102 cardiomyopathy events; 14.6/100,000 person-years [95% CI, 12.0-17.8]; adjusted HR, 1.89 [95% CI, 1.55-2.23]; in 213,197 person-years of follow-up among women with gestational hypertension, n = 40 cardiomyopathy events; 17.3/100,000 person-years [95% CI, 12.7-23.6]; adjusted HR, 2.06 [95% CI, 1.50-2.82]). These increases persisted more than 5 years after the latest pregnancy. Mediation analyses suggested that only about 50% of the association was an indirect association through postpregnancy chronic hypertension. In this cohort, 11% of all cardiomyopathy events occurred in women with a history of hypertensive disorders of pregnancy.

CONCLUSIONS AND RELEVANCE

Women with a history of hypertensive disorders of pregnancy, compared with women without such a history, had a small but statistically significant increased risk of cardiomyopathy more than 5 months after delivery. Further research is necessary to understand whether there is a causal mechanism behind this association.

The Influence of Age and Sex on Genetic Associations with Adult Body Size and Shape: A Large-Scale Genome-Wide Interaction Study

Genome-wide association studies (GWAS) have identified more than 100 genetic variants contributing to BMI, a measure of body size, or waist-to-hip ratio (adjusted for BMI, WHR_adjBMI), a measure of body shape. Body size and shape change as people grow older and these changes differ substantially between men and women. To systematically screen for age- and/or sex-specific effects of genetic variants on BMI and WHR_adjBMI, we performed meta-analyses of 114 studies (up to 320,485 individuals of European descent) with genome-wide chip and/or Metabochip data by the Genetic Investigation of Anthropometric Traits (GIANT) Consortium. Each study tested the association of up to ~2.8M SNPs with BMI and WHR_adjBMI in four strata (men ≤50y, men >50y, women ≤50y, women >50y) and summary statistics were combined in stratum-specific meta-analyses. We then screened for variants that showed age-specific effects (G x AGE), sex-specific effects (G x SEX) or age-specific effects that differed between men and women (G x AGE x SEX). For BMI, we identified 15 loci (11 previously established for main effects, four novel) that showed significant (FDR<5%) age-specific effects, of which 11 had larger effects in younger (<50y) than in older adults (≥50y). No sex-dependent effects were identified for BMI. For WHR_adjBMI, we identified 44 loci (27 previously established for main effects, 17 novel) with sex-specific effects, of which 28 showed larger effects in women than in men, five showed larger effects in men than in women, and 11 showed opposite effects between sexes. No age-dependent effects were identified for WHR_adjBMI. This is the first genome-wide interaction meta-analysis to report convincing evidence of age-dependent genetic effects on BMI. In addition, we confirm the sex-specificity of genetic effects on WHR_adjBMI. These results may provide further insights into the biology that underlies weight change with age or the sexually dimorphism of body shape.

Adult body size and body shape differ substantially between men and women and change over time. More than 100 genetic variants that influence body mass index (measure of body size) or waist-to-hip ratio (measure of body shape) have been identified. While there is evidence that some genetic loci affect body shape differently in men than in women, little is known about whether genetic effects differ in older compared to younger adults, and whether such changes differ between men and women. Therefore, we conducted a systematic genome-wide search, including 114 studies (>320,000 individuals), to specifically identify genetic loci with age- and or sex-dependent effects on body size and shape. We identified 15 loci of which the effect on BMI was different in older compared to younger adults, whereas we found no evidence for loci with different effects in men compared to women. The opposite was seen for body shape as we identified 44 loci of which the effect on waist-to-hip ratio differed between men and women, but no difference between younger and older adults were observed. Our observations may provide new insights into the biology that underlies weight change with age or the sexual dimorphism of body shape.

Risk of Cardiomyopathy in Younger Persons With a Family History of Death from Cardiomyopathy: A Nationwide Family Study in a Cohort of 3.9 Million Persons

BACKGROUND

Recommendations for presymptomatic screening of relatives of cardiomyopathy patients are based on findings from tertiary centers. Cardiomyopathy inheritance patterns are fairly well understood, but how cardiomyopathy in younger persons (<50 years) aggregates in families at the population level is unclear. In a nationwide cohort, we examined the risk of cardiomyopathy by family history of premature death (<60 years) from cardiomyopathy.

METHODS AND RESULTS

By linking Danish national register data, we constructed a cohort of 3.9 million persons born from 1950 to 2008. We ascertained family history of premature (<60 years) death from cardiomyopathy or other conditions, and cohort members were followed from 1977 to 2008 for cardiomyopathy diagnosed at <50 years. We identified 3890 cardiomyopathies in 89 million person-years of follow-up. Using Poisson regression, we estimated incidence rate ratios for cardiomyopathy by family history of premature death. Premature cardiomyopathy deaths in first- and second-degree relatives were associated with 29- and 6-fold increases in the rate of cardiomyopathy, respectively. If the first-degree relative died aged <35 years, the rate of cardiomyopathy increased 100-fold; given ≥2 premature deaths in first-degree relatives, the rate increased more than 400-fold. In contrast, a family history of premature death from other cardiac or noncardiac conditions increased the rate of cardiomyopathy 3-fold at most.

CONCLUSIONS

A family history of premature cardiomyopathy death was associated with an increase in risk of cardiomyopathy ranging from 6- to 400-fold, depending on age, kinship, gender and number of affected family members. Our general population-based results support recommendations for presymptomatic screening of relatives of cardiomyopathy patients.

Inflammatory Bowel Disease and Risk of Adverse Pregnancy Outcomes

BACKGROUND AND OBJECTIVES

Existing data on pregnancy complications in inflammatory bowel disease (IBD) are inconsistent. To address these inconsistencies, we investigated potential associations between IBD, IBD-related medication use during pregnancy, and pregnancy loss, pre-eclampsia, preterm delivery, Apgar score, and congenital abnormalities.

METHODS

We conducted a cohort study in >85,000 Danish National Birth Cohort women who were pregnant in the period 1996-2002 and had information on IBD, IBD-related medication use (systemic or local corticosteroids, 5-aminosalicylates), pregnancy outcomes and potential confounders. We evaluated associations between IBD and adverse pregnancy/birth outcomes using Cox regression and log-linear binomial regression.

RESULTS

IBD was strongly and significantly associated with severe pre-eclampsia, preterm premature rupture of membranes and medically indicated preterm delivery in women using systemic corticosteroids during pregnancy (hazard ratios [HRs] >7). IBD was also associated with premature preterm rupture of membranes in women using local corticosteroid medications (HR 3.30, 95% confidence interval [CI] 1.33-8.20) and with medically indicated preterm delivery (HR 1.91, 95% CI 0.99-3.68) in non-medicated women. Furthermore, IBD was associated with low 5-minute Apgar score in term infants (risk ratio [RR] 2.19, 95% CI 1.03-4.66). Finally, Crohn's disease (but not ulcerative colitis) was associated with major congenital abnormalities in the offspring (RR 1.85, 95% CI 1.06-3.21). No child with a congenital abnormality born to a woman with IBD was exposed to systemic corticosteroids in utero.

CONCLUSION

Women with IBD are at increased risk of severe pre-eclampsia, medically indicated preterm delivery, preterm premature rupture of membranes, and delivering infants with low Apgar score and major congenital malformations. These associations are only partly explained by severe disease as reflected by systemic corticosteroid use.

A detailed family history of myocardial infarction and risk of myocardial infarction--a nationwide cohort study

BACKGROUND

Family history of myocardial infarction (MI) is an independent risk factor for MI. Several genetic variants are associated with increased risk of MI and family history of MI in a first-degree relative doubles MI risk. However, although family history of MI is not a simple dichotomous risk factor, the impact of specific, detailed family histories has not received much attention, despite its high clinical relevance. We examined risk of MI by MIs in first- and second-degree relatives and by number and age of affected relatives.

METHODS AND FINDINGS

Using Danish national registers, we established a nationwide cohort of persons born between 1930 and 1992 with identifiable first- or second-degree relatives. Incident MIs in both cohort members and relatives aged ≥20 years were identified. We calculated incidence rate ratios (IRRs) for MI by family history of MI, by Poisson regression. In 4.4 million persons followed for 104 million person-years, we identified 128,384 incident MIs. IRRs with 95% confidence intervals [CIs] for MI by history of MI in 1, 2 or ≥3 first-degree relatives were 1.46 (1.42-1.49), 2.38 (2.22-2.56) and 3.58 (2.66-4.81), respectively. Corresponding estimates for second-degree relatives were 1.17 (1.05-1.30), 1.87 (1.46-2.38) and 2.18 (1.09-4.36). A history of MI in combinations of first- and second-degree relatives increased risks 1.8- to 7-fold in middle-aged persons (36 to 55 years). Estimates were robust to adjustment for diabetes, hypertension, dyslipidemia and use of cardiovascular medications.

CONCLUSION

A detailed family history, particularly number of affected first- and second-degree relatives, contributes meaningfully to risk assessment, especially in middle-aged persons. Future studies should test for potential improvement of risk algorithm prediction using detailed family histories.

Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption

Coffee, a major dietary source of caffeine, is among the most widely consumed beverages in the world and has received considerable attention regarding health risks and benefits. We conducted a genome-wide (GW) meta-analysis of predominately regular-type coffee consumption (cups per day) among up to 91,462 coffee consumers of European ancestry with top single-nucleotide polymorphisms (SNPs) followed-up in ~30 062 and 7964 coffee consumers of European and African-American ancestry, respectively. Studies from both stages were combined in a trans-ethnic meta-analysis. Confirmed loci were examined for putative functional and biological relevance. Eight loci, including six novel loci, met GW significance (log10Bayes factor (BF)>5.64) with per-allele effect sizes of 0.03-0.14 cups per day. Six are located in or near genes potentially involved in pharmacokinetics (ABCG2, AHR, POR and CYP1A2) and pharmacodynamics (BDNF and SLC6A4) of caffeine. Two map to GCKR and MLXIPL genes related to metabolic traits but lacking known roles in coffee consumption. Enhancer and promoter histone marks populate the regions of many confirmed loci and several potential regulatory SNPs are highly correlated with the lead SNP of each. SNP alleles near GCKR, MLXIPL, BDNF and CYP1A2 that were associated with higher coffee consumption have previously been associated with smoking initiation, higher adiposity and fasting insulin and glucose but lower blood pressure and favorable lipid, inflammatory and liver enzyme profiles (P<5 × 10(-8)).Our genetic findings among European and African-American adults reinforce the role of caffeine in mediating habitual coffee consumption and may point to molecular mechanisms underlying inter-individual variability in pharmacological and health effects of coffee.

Defining the role of common variation in the genomic and biological architecture of adult human height

Using genome-wide data from 253,288 individuals, we identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height. By testing different numbers of variants in independent studies, we show that the most strongly associated ∼2,000, ∼3,700 and ∼9,500 SNPs explained ∼21%, ∼24% and ∼29% of phenotypic variance. Furthermore, all common variants together captured 60% of heritability. The 697 variants clustered in 423 loci were enriched for genes, pathways and tissue types known to be involved in growth and together implicated genes and pathways not highlighted in earlier efforts, such as signaling by fibroblast growth factors, WNT/β-catenin and chondroitin sulfate-related genes. We identified several genes and pathways not previously connected with human skeletal growth, including mTOR, osteoglycin and binding of hyaluronic acid. Our results indicate a genetic architecture for human height that is characterized by a very large but finite number (thousands) of causal variants.

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche

Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition.

Associations of personal and family preeclampsia history with the risk of early-, intermediate- and late-onset preeclampsia

Preeclampsia encompasses multiple conditions of varying severity. We examined the recurrence and familial aggregation of preeclampsia by timing of onset, which is a marker for severity. We ascertained personal and family histories of preeclampsia for women who delivered live singletons in Denmark in 1978-2008 (almost 1.4 million pregnancies). Using log-linear binomial regression, we estimated risk ratios for the associations between personal and family histories of preeclampsia and the risk of early-onset (before 34 weeks of gestation, which is typically the most severe), intermediate-onset (at 34-36 weeks of gestation), and late-onset (after 36 weeks of gestation) preeclampsia. Previous early-, intermediate-, or late-onset preeclampsia increased the risk of recurrent preeclampsia with the same timing of onset 25.2 times (95% confidence interval (CI): 21.8, 29.1), 19.7 times (95% CI: 17.0, 22.8), and 10.3 times (95% CI: 9.85, 10.9), respectively, compared with having no such history. Preeclampsia in a woman's family was associated with a 24%-163% increase in preeclampsia risk, with the strongest associations for early- and intermediate-onset preeclampsia in female relatives. Preeclampsia in the man's family did not affect a woman's risk of early-onset preeclampsia and was only weakly associated with her risks of intermediate- and late-onset preeclampsia. Early-onset preeclampsia appears to have the largest genetic component, whereas environmental factors likely contribute most to late-onset preeclampsia. The role of paternal genes in the etiology of preeclampsia appears to be limited.

Vitamin D status during pregnancy and the risk of subsequent postpartum depression: a case-control study

Epidemiological studies have provided evidence of an association between vitamin D insufficiency and depression and other mood disorders, and a role for vitamin D in various brain functions has been suggested. We hypothesized that low vitamin D status during pregnancy might increase the risk of postpartum depression (PPD). The objective of the study was thus to determine whether low vitamin D status during pregnancy was associated with postpartum depression. In a case-control study nested in the Danish National Birth Cohort, we measured late pregnancy serum concentrations of 25[OH]D3 in 605 women with PPD and 875 controls. Odds ratios [OR) for PPD were calculated for six levels of 25[OH]D3. Overall, we found no association between vitamin D concentrations and risk of PPD (p = 0.08). Compared with women with vitamin D concentrations between 50 and 79 nmol/L, the adjusted odds ratios for PPD were 1.35 (95% CI: 0.64; 2.85), 0.83 (CI: 0.50; 1.39) and 1.13 (CI: 0.84; 1.51) among women with vitamin D concentrations < 15 nmol/L, 15–24 nmol/L and 25–49 nmol/L, respectively, and 1.53 (CI: 1.04; 2.26) and 1.89 (CI: 1.06; 3.37) among women with vitamin D concentrations of 80–99 nmol/L and ≥ 100 nmol/L, respectively. In an additional analysis among women with sufficient vitamin D (≥ 50 nmol/L), we observed a significant positive association between vitamin D concentrations and PPD. Our results did not support an association between low maternal vitamin D concentrations during pregnancy and risk of PPD. Instead, an increased risk of PPD was found among women with the highest vitamin D concentrations.

Association of maternal CNVs in GSTT1/GSTT2 with smoking, preterm delivery, and low birth weight

Preterm delivery (PTD) is an adverse birth outcome associated with increased infant mortality and negative lifelong health consequences. PTD may be the result of interactions between genetics and maternal/fetal environmental factors including smoking exposure (SMK). A common deletion in the GSTT1 gene was previously reported to affect birth outcomes in smokers. In this study, we dissect the associations among SMK, birth outcomes, and copy number variations (CNVs) in the GSTT1/GSTT2 region. A preterm birth case-control dataset of 1937 mothers was part of the GENEVA preterm birth study, which included genome-wide genotyping used to identify CNVs. We examined the association of SMK with birth outcomes, detected CNVs within the GSTT1/GSTT2 region using PennCNV, and examined associations of the identified CNVs with preterm birth and with birth weight (BW) in full term birth controls, including interactions with SMK. Finally, we tested the association of CNVs in GSTT1/GSTT2 with SMK. We confirmed the association of smoking with low BW and PTD. We identified 2 CNVs in GSTT2 (GSTT2^a and GSTT2^b), 1 CNV in GSTTP1 and 2 CNVs in GSTT1 (GSTT1^a and GSTT1^b). The GSTT2^a deletion was associated with reduced BW (−284 g, p = 2.50E-7) in smokers, and was more common in smokers [odds ratio(OR) = 1.30, p = 0.04]. We found that the size of the reported common deletion CNV in GSTT1 was larger than previously shown. The GSTTP1 and GSTT1^b null genotypes were in high linkage disequilibrium (LD) (D′ = 0.89) and less common in smokers (OR = 0.68, p = 0.019 and OR = 0.73, p = 0.055, respectively). These two deletions were in partial LD with GSTT2^a and GSTT2^b duplications. All 5 CNVs seem to be associated with increased risk of preterm birth before 35 completed weeks. CNVs in the GSTTT1/GSTT2 region appear associated with low BW and PTD outcomes, but LD complicated these CNVs in GSTT1/GSTT2. In genetic association studies of BW, multiple CNVs in this region need to be investigated instead of a single polymorphism.

Association of adiposity genetic variants with menarche timing in 92,105 women of European descent

Obesity is of global health concern. There are well-described inverse relationships between female pubertal timing and obesity. Recent genome-wide association studies of age at menarche identified several obesity-related variants. Using data from the ReproGen Consortium, we employed meta-analytical techniques to estimate the associations of 95 a priori and recently identified obesity-related (body mass index (weight (kg)/height (m)(2)), waist circumference, and waist:hip ratio) single-nucleotide polymorphisms (SNPs) with age at menarche in 92,116 women of European descent from 38 studies (1970-2010), in order to estimate associations between genetic variants associated with central or overall adiposity and pubertal timing in girls. Investigators in each study performed a separate analysis of associations between the selected SNPs and age at menarche (ages 9-17 years) using linear regression models and adjusting for birth year, site (as appropriate), and population stratification. Heterogeneity of effect-measure estimates was investigated using meta-regression. Six novel associations of body mass index loci with age at menarche were identified, and 11 adiposity loci previously reported to be associated with age at menarche were confirmed, but none of the central adiposity variants individually showed significant associations. These findings suggest complex genetic relationships between menarche and overall obesity, and to a lesser extent central obesity, in normal processes of growth and development.

Sequence variants in oxytocin pathway genes and preterm birth: a candidate gene association study

Background

Preterm birth (PTB) is a complex disorder associated with significant neonatal mortality and morbidity and long-term adverse health consequences. Multiple lines of evidence suggest that genetic factors play an important role in its etiology. This study was designed to identify genetic variation associated with PTB in oxytocin pathway genes whose role in parturition is well known.

Methods

To identify common genetic variants predisposing to PTB, we genotyped 16 single nucleotide polymorphisms (SNPs) in the oxytocin (OXT), oxytocin receptor (OXTR), and leucyl/cystinyl aminopeptidase (LNPEP) genes in 651 case infants from the U.S. and one or both of their parents. In addition, we examined the role of rare genetic variation in susceptibility to PTB by conducting direct sequence analysis of OXTR in 1394 cases and 1112 controls from the U.S., Argentina, Denmark, and Finland. This study was further extended to maternal triads (maternal grandparents-mother of a case infant, N=309). We also performed in vitro analysis of selected rare OXTR missense variants to evaluate their functional importance.

Results

Maternal genetic effect analysis of the SNP genotype data revealed four SNPs in LNPEP that show significant association with prematurity. In our case–control sequence analysis, we detected fourteen coding variants in exon 3 of OXTR, all but four of which were found in cases only. Of the fourteen variants, three were previously unreported novel rare variants. When the sequence data from the maternal triads were analyzed using the transmission disequilibrium test, two common missense SNPs (rs4686302 and rs237902) in OXTR showed suggestive association for three gestational age subgroups. In vitro functional assays showed a significant difference in ligand binding between wild-type and two mutant receptors.

Conclusions

Our study suggests an association between maternal common polymorphisms in LNPEP and susceptibility to PTB. Maternal OXTR missense SNPs rs4686302 and rs237902 may have gestational age-dependent effects on prematurity. Most of the OXTR rare variants identified do not appear to significantly contribute to the risk of PTB, but those shown to affect receptor function in our in vitro study warrant further investigation. Future studies with larger sample sizes are needed to confirm the findings of this study.

Increased genetic vulnerability to smoking at CHRNA5 in early-onset smokers

CONTEXT

Recent studies have shown an association between cigarettes per day (CPD) and a nonsynonymous single-nucleotide polymorphism in CHRNA5, rs16969968.

OBJECTIVE

To determine whether the association between rs16969968 and smoking is modified by age at onset of regular smoking.

DATA SOURCES

Primary data.

STUDY SELECTION

Available genetic studies containing measures of CPD and the genotype of rs16969968 or its proxy.

DATA EXTRACTION

Uniform statistical analysis scripts were run locally. Starting with 94,050 ever-smokers from 43 studies, we extracted the heavy smokers (CPD >20) and light smokers (CPD ≤10) with age-at-onset information, reducing the sample size to 33,348. Each study was stratified into early-onset smokers (age at onset ≤16 years) and late-onset smokers (age at onset >16 years), and a logistic regression of heavy vs light smoking with the rs16969968 genotype was computed for each stratum. Meta-analysis was performed within each age-at-onset stratum.

DATA SYNTHESIS

Individuals with 1 risk allele at rs16969968 who were early-onset smokers were significantly more likely to be heavy smokers in adulthood (odds ratio [OR] = 1.45; 95% CI, 1.36-1.55; n = 13,843) than were carriers of the risk allele who were late-onset smokers (OR = 1.27; 95% CI, 1.21-1.33, n = 19,505) (P = .01).

CONCLUSION

These results highlight an increased genetic vulnerability to smoking in early-onset smokers.

Common variants near MBNL1 and NKX2-5 are associated with infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is a severe condition characterized by hypertrophy of the pyloric sphincter muscle. We conducted a genome-wide association study (GWAS) on 1,001 surgery-confirmed cases and 2,401 controls from Denmark. The six most strongly associated loci were tested in a replication set of 796 cases and 876 controls. Three SNPs reached genome-wide significance. One of these SNPs, rs11712066 (odds ratio (OR) = 1.61; P = 1.5 × 10(-17)) at 3p25.1, is located 150 kb upstream of MBNL1, which encodes a factor that regulates splicing transitions occurring shortly after birth. The second SNP, rs573872 (OR = 1.41; P = 4.3 × 10(-12)), maps to an intergenic region at 3p25.2 approximately 1.3 Mb downstream of MBNL1. The third SNP, rs29784 (OR = 1.42; P = 1.5 × 10(-15)) at 5q35.2, is 64 kb downstream of NKX2-5, which is involved in development of cardiac muscle tissue and embryonic gut development.

Genome-wide association scan for childhood caries implicates novel genes

Dental caries is the most common chronic disease in children and a major public health concern due to its increasing incidence, serious health and social co-morbidities, and socio-demographic disparities in disease burden. We performed the first genome-wide association scan for dental caries to identify associated genetic loci and nominate candidate genes affecting tooth decay in 1305 US children ages 3-12 yrs. Affection status was defined as 1 or more primary teeth with evidence of decay based on intra-oral examination. No associations met strict criteria for genome-wide significance (p < 10E-7); however, several loci (ACTN2, MTR, and EDARADD, MPPED2, and LPO) with plausible biological roles in dental caries exhibited suggestive evidence for association. Analyses stratified by home fluoride level yielded additional suggestive loci, including TFIP11 in the low-fluoride group, and EPHA7 and ZMPSTE24 in the sufficient-fluoride group. Suggestive loci were tested but not significantly replicated in an independent sample (N = 1695, ages 2-7 yrs) after adjustment for multiple comparisons. This study reinforces the complexity of dental caries, suggesting that numerous loci, mostly having small effects, are involved in cariogenesis. Verification/replication of suggestive loci may highlight biological mechanisms and/or pathways leading to a fuller understanding of the genetic risks for dental caries.

Sequence variants at CYP1A1-CYP1A2 and AHR associate with coffee consumption

Coffee is the most commonly used stimulant and caffeine is its main psychoactive ingredient. The heritability of coffee consumption has been estimated at around 50%. We performed a meta-analysis of four genome-wide association studies of coffee consumption among coffee drinkers from Iceland (n = 2680), The Netherlands (n = 2791), the Sorbs Slavonic population isolate in Germany (n = 771) and the USA (n = 369) using both directly genotyped and imputed single nucleotide polymorphisms (SNPs) (2.5 million SNPs). SNPs at the two most significant loci were also genotyped in a sample set from Iceland (n = 2430) and a Danish sample set consisting of pregnant women (n = 1620). Combining all data, two sequence variants significantly associated with increased coffee consumption: rs2472297-T located between CYP1A1 and CYP1A2 at 15q24 (P = 5.4 · 10(-14)) and rs6968865-T near aryl hydrocarbon receptor (AHR) at 7p21 (P = 2.3 · 10(-11)). An effect of ∼0.2 cups a day per allele was observed for both SNPs. CYP1A2 is the main caffeine metabolizing enzyme and is also involved in drug metabolism. AHR detects xenobiotics, such as polycyclic aryl hydrocarbons found in roasted coffee, and induces transcription of CYP1A1 and CYP1A2. The association of these SNPs with coffee consumption was present in both smokers and non-smokers.