Importance of gene-environment interactions in the etiology of selected birth defects

Impact of genetic factors on antioxidant rescue of maternal diabetes-associated congenital heart disease

Congenital heart disease (CHD) affects approximately 1% of live births. Although genetic and environmental etiologic contributors have been identified, the majority of CHD lacks a definitive cause, suggesting the role of gene-environment interactions (GxEs) in disease pathogenesis. Maternal diabetes mellitus (matDM) is among the most prevalent environmental risk factors for CHD. However, there is a substantial knowledge gap in understanding how matDM acts upon susceptible genetic backgrounds to increase disease expressivity. Previously, we reported a GxE between Notch1 haploinsufficiency and matDM leading to increased CHD penetrance. Here, we demonstrate a cell lineage-specific effect of Notch1 haploinsufficiency in matDM-exposed embryos, implicating endothelial/endocardial tissues in the developing heart. We report impaired atrioventricular cushion morphogenesis in matDM-exposed Notch1+/- animals and show a synergistic effect of NOTCH1 haploinsufficiency and oxidative stress in dysregulation of gene regulatory networks critical for endocardial cushion morphogenesis in vitro. Mitigation of matDM-associated oxidative stress via superoxide dismutase 1 overexpression did not rescue CHD in Notch1-haploinsufficient mice compared to wild-type littermates. Our results show the combinatorial interaction of matDM-associated oxidative stress and a genetic predisposition, Notch1 haploinsufficiency, on cardiac development, supporting a GxE model for CHD etiology and suggesting that antioxidant strategies alone may be ineffective in genetically susceptible individuals.

From genes to therapy: A comprehensive exploration of congenital heart disease through the lens of genetics and emerging technologies

Congenital heart disease (CHD) affects approximately 1 % of live births worldwide, making it the most common congenital anomaly in newborns. Recent advancements in genetics and genomics have significantly deepened our understanding of the genetics of CHDs. While the majority of CHD etiology remains unclear, evidence consistently indicates that genetics play a significant role in its development. CHD etiology holds promise for enhancing diagnosis and developing novel therapies to improve patient outcomes. In this review, we explore the contributions of both monogenic and polygenic factors of CHDs and highlight the transformative impact of emerging technologies on these fields. We also summarized the state-of-the-art techniques, including targeted next-generation sequencing (NGS), whole genome and whole exome sequencing (WGS, WES), single-cell RNA sequencing (scRNA-seq), human induced pluripotent stem cells (hiPSCs) and others, that have revolutionized our understanding of cardiovascular disease genetics both from diagnosis perspective and from disease mechanism perspective in children and young adults. These molecular diagnostic techniques have identified new genes and chromosomal regions involved in syndromic and non-syndromic CHD, enabling a more defined explanation of the underlying pathogenetic mechanisms. As our knowledge and technologies continue to evolve, they promise to enhance clinical outcomes and reduce the CHD burden worldwide.

Metabolic plasticity sustains the robustness of Caenorhabditis elegans embryogenesis

Embryogenesis is highly dependent on maternally loaded materials, particularly those used for energy production. Different environmental conditions and genetic backgrounds shape embryogenesis. The robustness of embryogenesis in response to extrinsic and intrinsic changes remains incompletely understood. By analyzing the levels of two major nutrients, glycogen and neutral lipids, we discovered stage-dependent usage of these two nutrients along with mitochondrial morphology changes during Caenorhabditis elegans embryogenesis. ATGL, the rate-limiting lipase in cellular lipolysis, is expressed and required in the hypodermis to regulate mitochondrial function and support embryogenesis. The embryonic lethality of atgl-1 mutants can be suppressed by reducing sinh-1/age-1-akt signaling, likely through modulating glucose metabolism to maintain sustainable glucose consumption. The embryonic lethality of atgl-1(xd314) is also affected by parental nutrition. Parental glucose and oleic acid supplements promote glycogen storage in atgl-1(xd314) embryos to compensate for the impaired lipolysis. The rescue by parental vitamin B12 supplement is likely through enhancing mitochondrial function in atgl-1 mutants. These findings reveal that metabolic plasticity contributes to the robustness of C. elegans embryogenesis.

Maternal Pre-Existing Diabetes: A Non-Inherited Risk Factor for Congenital Cardiopathies

Congenital heart defects (CHDs) are the most common form of birth defects in humans. They occur in 9 out of 1000 live births and are defined as structural abnormalities of the heart. Understanding CHDs is difficult due to the heterogeneity of the disease and its multifactorial etiology. Advances in genomic sequencing have made it possible to identify the genetic factors involved in CHDs. However, genetic origins have only been found in a minority of CHD cases, suggesting the contribution of non-inherited (environmental) risk factors to the etiology of CHDs. Maternal pregestational diabetes is associated with a three- to five-fold increased risk of congenital cardiopathies, but the underlying molecular mechanisms are incompletely understood. According to current hypotheses, hyperglycemia is the main teratogenic agent in diabetic pregnancies. It is thought to induce cell damage, directly through genetic and epigenetic dysregulations and/or indirectly through production of reactive oxygen species (ROS). The purpose of this review is to summarize key findings on the molecular mechanisms altered in cardiac development during exposure to hyperglycemic conditions in utero. It also presents the various in vivo and in vitro techniques used to experimentally model pregestational diabetes. Finally, new approaches are suggested to broaden our understanding of the subject and develop new prevention strategies.

A gene-based association test of interactions for maternal-fetal genotypes identifies genes associated with nonsyndromic congenital heart defects

The risk of congenital heart defects (CHDs) may be influenced by maternal genes, fetal genes, and their interactions. Existing methods commonly test the effects of maternal and fetal variants one-at-a-time and may have reduced statistical power to detect genetic variants with low minor allele frequencies. In this article, we propose a gene-based association test of interactions for maternal-fetal genotypes (GATI-MFG) using a case-mother and control-mother design. GATI-MFG can integrate the effects of multiple variants within a gene or genomic region and evaluate the joint effect of maternal and fetal genotypes while allowing for their interactions. In simulation studies, GATI-MFG had improved statistical power over alternative methods, such as the single-variant test and functional data analysis (FDA) under various disease scenarios. We further applied GATI-MFG to a two-phase genome-wide association study of CHDs for the testing of both common variants and rare variants using 947 CHD case mother-infant pairs and 1306 control mother-infant pairs from the National Birth Defects Prevention Study (NBDPS). After Bonferroni adjustment for 23,035 genes, two genes on chromosome 17, TMEM107 (p = 1.64e-06) and CTC1 (p = 2.0e-06), were identified for significant association with CHD in common variants analysis. Gene TMEM107 regulates ciliogenesis and ciliary protein composition and was found to be associated with heterotaxy. Gene CTC1 plays an essential role in protecting telomeres from degradation, which was suggested to be associated with cardiogenesis. Overall, GATI-MFG outperformed the single-variant test and FDA in the simulations, and the results of application to NBDPS samples are consistent with existing literature supporting the association of TMEM107 and CTC1 with CHDs.

Outcome monitoring and risk stratification after cardiac procedure in neonates, infants, children and young adults born with congenital heart disease: protocol for a multicentre prospective cohort study (Children OMACp)

INTRODUCTION

Congenital heart disease (CHD) represents the most common birth defect, affecting from 0.4% to 1.2% of children born in developed countries. The survival of these patients has increased significantly, but CHD remains one of the major causes of neonatal and childhood death. The aetiology of CHD is complex, with some evidence of both genetic and environmental causes. However, there is still lack of knowledge regarding modifiable risk factors and molecular and genetic mechanisms underlying the development of CHD. This study aims to develop a prospective cohort of patients undergoing cardiac procedures that will bring together routinely collected clinical data and biological samples from patients and their biological mothers, in order to investigate risk factors and predictors of postoperative-outcomes, as well as better understanding the effect of the surgical intervention on the early and long-term outcomes.

METHODS AND ANALYSIS

Children OMACp (OMACp, outcome monitoring after cardiac procedure in congenital heart disease) is a multicentre, prospective cohort study recruiting children with CHD undergoing a cardiac procedure. The study aims to recruit 3000 participants over 5 years (2019-2024) across multiple UK sites. Routine clinical data will be collected, as well as participant questionnaires collecting sociodemographic, NHS resource use and quality of life data. Biological samples (blood, urine and surgical waste tissue from patients, and blood and urine samples from biological mothers) will be collected where consent has been obtained. Follow-up outcome and questionnaire data will be collected for 5 years.

ETHICS AND DISSEMINATION

The study was approved by the London-Brent Research Ethics Committee on 30 July 2019 (19/SW/0113). Participants (or their parent/guardian if under 16 years of age) must provide informed consent prior to being recruited into the study. Mothers who wish to take part must also provide informed consent prior to being recruited. The study is sponsored by University Hospitals Bristol and Weston Foundation Trust and is managed by the University of Bristol. Children OMACp is adopted onto the National Institute for Health Research Clinical Research Network portfolio. Findings will be disseminated through peer-reviewed publications, presentation at conference, meetings and through patient organisations and newsletters.

TRIAL REGISTRATION NUMBER

ISRCTN17650644.

Hydrogel Drug Delivery Systems for Bone Regeneration

With the in-depth understanding of bone regeneration mechanisms and the development of bone tissue engineering, a variety of scaffold carrier materials with desirable physicochemical properties and biological functions have recently emerged in the field of bone regeneration. Hydrogels are being increasingly used in the field of bone regeneration and tissue engineering because of their biocompatibility, unique swelling properties, and relative ease of fabrication. Hydrogel drug delivery systems comprise cells, cytokines, an extracellular matrix, and small molecule nucleotides, which have different properties depending on their chemical or physical cross-linking. Additionally, hydrogels can be designed for different types of drug delivery for specific applications. In this paper, we summarize recent research in the field of bone regeneration using hydrogels as delivery carriers, detail the application of hydrogels in bone defect diseases and their mechanisms, and discuss future research directions of hydrogel drug delivery systems in bone tissue engineering.

Associations between severe and notifiable respiratory infections during the first trimester of pregnancy and congenital anomalies at birth: a register-based cohort study

BACKGROUND

Evidence regarding the association between acute respiratory infections during pregnancy and congenital anomalies in babies, is limited and conflicting. The aim of this study was to examine the association between acute respiratory infections during the first trimester of pregnancy and congenital anomalies in babies using record linkage.

METHODS

We linked a perinatal register to hospitalisation and disease notifications in the Australian state of New South Wales (NSW) between 2001 to 2016. We quantified the risk of congenital anomalies, identified from the babies' linked hospital record in relation to notifiable respiratory and other infections during pregnancy using generalized Estimating Equations (GEE) adjusted for maternal sociodemographic and other characteristics.

RESULTS

Of 1,453,037 birth records identified from the perinatal register between 2001 and 2016, 11,710 (0.81%) mothers were hospitalised for acute respiratory infection, 2850 (0.20%) had influenza and 1011 (0.07%) had high risk infections (a record of cytomegalovirus, rubella, herpes simplex, herpes zoster, toxoplasmosis, syphilis, chickenpox (varicella) and zika) during the pregnancy. During the first trimester, acute respiratory infection, influenza and high-risk infections were reported by 1547 (0.11%), 399 (0.03%) and 129 (0.01%) mothers. There were 15,644 (1.08%) babies reported with major congenital anomalies, 2242 (0.15%) with cleft lip/ plate, 7770 (0.53%) with all major cardiovascular anomalies and 1746 (0.12%) with selected major cardiovascular anomalies. The rate of selected major cardiovascular anomalies was significantly higher if the mother had an acute respiratory infection during the first trimester of pregnancy (AOR 3.64, 95% CI 1.73 to 7.66). The rates of all major congenital anomalies and all major cardiovascular anomalies were also higher if the mother had an acute respiratory infection during the first trimester of pregnancy, however the difference was no statistically significant. Influenza during the first trimester was not associated with major congenital anomalies, selected major cardiovascular anomalies or all major cardiovascular anomalies in this study.

CONCLUSION

This large population-based study found severe acute respiratory infection in first trimester of pregnancy was associated with a higher risk of selected major cardiovascular anomalies in babies. These findings support measures to prevent acute respiratory infections in pregnant women including through vaccination.

Epigenetic Evaluation of the TBX20 Gene and Environmental Risk Factors in Mexican Paediatric Patients with Congenital Septal Defects

The TBX20 gene has a key role during cardiogenesis, and it has been related to epigenetic mechanisms in congenital heart disease (CHD). The purpose of this study was to assess the association between DNA methylation status and congenital septal defects. The DNA methylation of seven CpG sites in the TBX20 gene promoter was analyzed through pyrosequencing as a quantitative method in 48 patients with congenital septal defects and 104 individuals with patent ductus arteriosus (PDA). The average methylation was higher in patients than in PDA (p < 0.001). High methylation levels were associated with a higher risk of congenital septal defects (OR = 4.59, 95% CI = 1.57-13.44, p = 0.005). The ROC curve analysis indicated that methylation of the TBX20 gene could be considered a risk marker for congenital septal defects (AUC = 0.682; 95% CI = 0.58-0.77; p < 0.001). The analysis of environmental risk factors in patients with septal defects and PDA showed an association between the consumption of vitamins (OR = 0.10; 95% CI = 0.01-0.98; p = 0.048) and maternal infections (OR = 3.10; 95% CI = 1.26-7.60; p = 0.013). These results suggest that differences in DNA methylation of the TBX20 gene can be associated with septal defects.

Variation in the Mu-Opioid Receptor (OPRM1) and Offspring Sex Are Associated With Maternal Behavior in Rhesus Macaques (Macaca mulatta)

A μ-opioid receptor (OPRM1) single-nucleotide-polymorphism, found in both humans and rhesus macaques mediates the mother-infant attachment bond. Because mothers treat their sons and daughters differently, it is somewhat surprising that the role of infant sex has not been assessed in the context of a maternal-OPRM1-genotype-by-infant-sex interaction. The present study investigates the effect of maternal-OPRM1-genotype and infant sex on mother-infant behaviors. Over the first 6 months of offspring life, mother-infant behavioral data assessing attachment quality was collected twice weekly from a large number of rhesus monkey mother-infant pairs (N = 161 dyads; n = 64 female infants, n = 97 male infants). Mothers were genotyped for OPRM1 variation. Factor analysis of the observed behaviors showed two factors: Attachment (maternal-infant cradling, rejections, and infant approaches and leaves), and Maternal Restraints (mother restrains infant, preventing exploration). Further analyses showed a two-way, maternal-genotype-by-infant-sex interaction for both factors. For Attachment, mothers with the CC genotype cradled and restrained (Maternal Restraints) their female infants more and rejected them less, when compared to female infants of CG mothers. Perhaps as a consequence, female infants of CC genotype mothers approached and left their mothers less often, when compared to female infants of CG mothers, likely an indication that female infants from mothers with CG genotype play a greater role in maintaining the mother-infant bond than do female infants from CC genotype mothers. This finding may also indicate a more secure attachment in infants from CC genotype mothers. Unlike female infants, on average, the mother-infant relationship of dyads with a male infant was largely undifferentiated by maternal genotype. These findings suggest that, in contrast to female infants from CG mothers, CC mothers and their female infants appear to have a closer mother-infant relationship which may portend close life-long bonds, as mothers and female offspring remain together throughout life. Male offspring appear to have a more aloof mother-infant bond regardless of OPRM1-genotype. The results of this study indicate that maternal-OPRM1 variation mediates mother-infant attachment behaviors for female infants and has less effect for male infants. This suggests that offspring sex should be included in studies investigating the effect of maternal-OPRM1 genotype on the mother-infant attachment relationship.

Association of polymorphisms of FOLR1 gene and FOLR2 gene and maternal folic acid supplementation with risk of ventricular septal defect: a case-control study

OBJECTIVES

It was the first time to examine the role of maternal polymorphisms of FOLR1 gene and FOLR2 gene, as well as their interactions with maternal folic acid supplementation (FAS), in the risk of ventricular septal defect (VSD).

METHODS

A case-control study was conducted with 385 mothers of VSD infants and 652 controls. The exposures of interest were FAS and FOLR1 gene and FOLR2 gene polymorphisms. The logistic regression model was used for accessing the strength of association.

RESULTS

After controlling for the potential confounders, women who did not utilize folic acid had a substantially higher risk of VSD (aOR = 2.25; 95% CI: 1.48 to 3.43), compared to those who did. We also observed genetic polymorphisms of FOLR1 gene at rs2071010 (GA vs. GG: aOR = 0.63, 95%CI: 0.45 to 0.88) and rs11235462 (AA vs. TT: aOR = 0.53, 95%CI: 0.33 to 0.84), as well as FOLR2 gene at rs651646 (AA vs. TT: aOR = 0.46, 95%CI: 0.30 to 0.70), rs2298444 (CC vs. TT: aOR = 0.58, 95%CI: 0.36 to 0.91) and rs514933 (TC vs. TT: aOR = 0.57, 95%CI: 0.41 to 0.78) were associated with a lower risk of VSD. Furthermore, there was a statistically significant interaction between maternal FAS and genetic polymorphisms at rs514933 on the risk of VSD (FDR_P = 0.015).

CONCLUSIONS

The maternal genetic polymorphisms of the FOLR1 gene and FOLR2 gene, as well as FAS and their interactions, were shown to be significantly associated with the risk of VSD in offspring.

Association of MTHFD1 gene polymorphisms and maternal smoking with risk of congenital heart disease: a hospital-based case-control study

Background

MTHFD1 gene may affect the embryonic development by elevated homocysteine levels, DNA synthesis and DNA methylation, but limited number of genetic variants of MTHFD1 gene was focused on the association with congenital heart disease (CHD). This study examined the role of MTHFD1 gene and maternal smoking on infant CHD risk, and investigated their interaction effects in Chinese populations.

Methods

A case-control study of 464 mothers of CHD infants and 504 mothers of health controls was performed. The exposures of interest were maternal tobacco exposure, single nucleotide polymorphisms (SNPs) of maternal MTHFD1 gene. The logistic regression model was used for accessing the strength of association.

Results

Mothers exposed to secondhand smoke during 3 months before pregnancy (adjusted odds ratio [aOR] = 1.56; 95% confidence interval [CI]: 1.13–2.15) and in the first trimester of pregnancy (aOR = 2.24; 95%CI: 1.57–3.20) were observed an increased risk of CHD. Our study also found that polymorphisms of maternal MTHFD1 gene at rs1950902 (AA vs. GG: aOR = 1.73, 95% CI: 1.01–2.97), rs2236222 (GG vs. AA: aOR = 2.38, 95% CI: 1.38–4.12), rs1256142 (GA vs.GG: aOR = 1.57, 95% CI: 1.01–2.45) and rs11849530 (GG vs. AA: aOR = 1.68, 95% CI: 1.02–2.77) were significantly associated with higher risk of CHD. However, we did not observe a significant association between maternal MTHFD1 rs2236225 and offspring CHD risk. Furthermore, we found the different degrees of interaction effects between polymorphisms of the MTHFD1 gene including rs1950902, rs2236222, rs1256142, rs11849530 and rs2236225, and maternal tobacco exposure.

Conclusions

Maternal polymorphisms of MTHFD1 gene, maternal tobacco exposure and their interactions are significantly associated with the risk of CHD in offspring in Han Chinese populations. However, more studies in different ethnic populations with a larger sample and prospective designs are required to confirm our findings.

Trial registration

Registration number: ChiCTR1800016635.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04419-2.

OUP accepted manuscript

BACKGROUND

Maternal exposure to pesticides during early pregnancy is associated with increased risks of birth defects, while the association between maternal exposure to chemical fertilizer during pregnancy and the risk of birth defects remains unknown.

METHODS

Data were from a population-based birth defects surveillance system between 2007 and 2012 in Pingding County, Shanxi Province, northern China. A total of 14 074 births with 235 birth defects were used to estimate spatial clustering and correlations at the village level. A population-based case-control study of 157 cases with birth defects and 204 controls was performed to investigate the association between maternal chemical fertilizer exposure and the risk of birth defects by a two-level logistic model.

RESULTS

The total prevalence of birth defects between 2007 and 2012 was 167.0/10 000 births. The spatial analysis indicated a remarkable high-risk area of birth defects in the southeast of Pingding County and the use of chemical fertilizer was associated with the risk of birth defects at the village level. After adjusting for confounders at the individual level, mothers who live in villages with chemical fertilizer application ≥65 tons/y had an increased risk of birth defects (adjusted odds ratio 2.06 [95% confidence interval 1.23 to 3.46]) compared with those of <65 tons/y.

CONCLUSIONS

Our findings suggest that the risk of birth defects may be associated with the use of chemical fertilizer in rural northern China. The findings must be cautiously interpreted and need to be investigated on larger samples.

Association of parental prepregnancy BMI with neonatal outcomes and birth defect in fresh embryo transfer cycles: a retrospective cohort study

Background

Parental body mass index (BMI) is associated with pregnancy outcomes. But the effect of parental prepregnancy BMI on offspring conceived via in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), especially the birth defect, remains to be determined. This study aimed to investigate the associations of parental prepregnancy BMI with neonatal outcomes and birth defect in fresh embryo transfer cycles.

Methods

We conducted a retrospective cohort study including 5741 couples in their first fresh IVF/ICSI cycles admitted to Women’s Hospital, School of Medicine, Zhejiang University from January 2013 to July 2016. The primary outcome was birth defects, which was classified according to the International Classification of Diseases, 10th Revision. Secondary outcomes included preterm delivery rate, infant gender, birth weight, small-for-gestational age (SGA) and large-for-gestational age (LGA). Multilevel regression analyses were used to assess the associations of parental prepregnancy BMI with neonatal outcomes and birth defect.

Results

In singletons, couples with prepregnancy BMI ≥25 kg/m² had higher odds of LGA than those with BMI < 25 kg/m². The birth defect rate was significantly higher when paternal prepregnancy BMI ≥25 kg/m² in IVF cycles (aOR 1.82, 95% CI 1.06–3.10) and maternal BMI ≥25 kg/m² in ICSI cycles (aOR 4.89, 95% CI 1.45–16.53). For subcategories of birth defects, only the odds of congenital malformations of musculoskeletal system was significantly increased in IVF offspring with paternal BMI ≥25 kg/m² (aOR 4.55, 95% CI 1.32–15.71). For twins, there was no significant difference among four groups, except for the lower birth weight of IVF female infants.

Conclusions

Parental prepregnancy BMI ≥25 kg/m² is associated with higher incidence of LGA in IVF/ICSI singletons. Paternal prepregnancy BMI ≥25 kg/m² was likely to have higher risk of birth defect in IVF offspring than those with BMI < 25 kg/m², particularly in the musculoskeletal system. It is essential for overweight or obesity couples to lose weight before IVF/ICSI treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04261-y.

Micronutrient imbalance and common phenotypes in neural tube defects

Neural tube defects (NTDs) are among the most common birth defects, with a prevalence of close to 19 per 10,000 births worldwide. The etiology of NTDs is complex involving the interplay of genetic and environmental factors. Since nutrient deficiency is a risk factor and dietary changes are the major preventative measure to reduce the risk of NTDs, a more detailed understanding of how common micronutrient imbalances contribute to NTDs is crucial. While folic acid has been the most discussed environmental factor due to the success that population-wide fortification has had on prevention of NTDs, folic acid supplementation does not prevent all NTDs. The imbalance of several other micronutrients has been implicated as risks for NTDs by epidemiological studies and in vivo studies in animal models. In this review, we highlight recent literature deciphering the multifactorial mechanisms underlying NTDs with an emphasis on mouse and human data. Specifically, we focus on advances in our understanding of how too much or too little retinoic acid, zinc, and iron alter gene expression and cellular processes contributing to the pathobiology of NTDs. Synthesis of the discussed literature reveals common cellular phenotypes found in embryos with NTDs resulting from several micronutrient imbalances. The goal is to combine knowledge of these common cellular phenotypes with mechanisms underlying micronutrient imbalances to provide insights into possible new targets for preventative measures against NTDs.

Prevalence of iron and folic acid supplements consumption and associated factors among pregnant women in Eswatini: a multicenter cross-sectional study

Background

During pregnancy, nutritional requirements increase and if not met, pregnancy-related complications may manifest. To prevent these undesirable outcomes, the World Health Organization recommends daily oral iron and folic acid (IFA) supplementation as part of antenatal care. Despite this recommendation, the use of IFA supplements is still very low in several developing countries. Additionally, no prior information exists regarding the level of consumption of IFA in Eswatini. Thus, this study aimed to determine the prevalence of consumption of IFA supplements and to identify factors associated with the consumption of IFA supplements among pregnant women in Eswatini.

Methods

A cross-sectional questionnaire survey was conducted among 330 pregnant women aged ≥ 18 years in their third trimester in Eswatini. Participants were recruited from eight purposively selected healthcare facilities from July 2019 to October 2019. Good consumption was defined as consuming all or almost all IFA supplements throughout pregnancy.

Results

During the first trimester, 10.3 % of the participants consumed all or almost all IFA supplements. In the second and third trimesters, those who consumed all or almost all supplements were 37 and 39.7 %, respectively, for iron and 37.6 and 40.9 %, respectively, for folic acid. Barriers, including side effects, forgetfulness, safe previous pregnancies without IFA, others’ advice against consumption, IFA stock-outs, inability to meet transport costs, and inadequate supply of IFA tablets, contribute to low consumption of IFA. Multivariate logistic regression models showed that the barriers were inversely associated with good consumption of IFA supplements. Better knowledge and attitude toward IFA and older maternal age were positively associated with good consumption of IFA supplements.

Conclusions

Low consumption of IFA supplements in overall pregnancy is mainly owing to the late antenatal care attendance. Strategies such as establishing a preconception care unit and school-based provision of IFA may be helpful. It is evident that most women still lack knowledge, and some have negative attitudes about IFA supplements. Health education to raise awareness and emphasize the importance of starting antenatal care early as well as consuming supplements on time should be revisited and intensified. Multiple strategies such as including community health care workers for distributing IFA supplements, discussing with clients about the measures to reduce forgetfulness, advising ways to prevent and manage the side effects, providing subsidies to cover transport costs, and ensuring adequate supply of IFA supplements in facilities may need to be employed to reduce the identified barriers.

Association analysis of maternal MTHFR gene polymorphisms and the occurrence of congenital heart disease in offspring

BACKGROUND

Although many studies showed that the risk of congenital heart disease (CHD) was closely related to genetic factors, the exact pathogenesis is still unknown. Our study aimed to comprehensively assess the association of single nucleotide polymorphisms (SNPs) of maternal MTHFR gene with risk of CHD and its three subtypes in offspring.

METHODS

A case-control study involving 569 mothers of CHD cases and 652 health controls was conducted. Thirteen SNPs were detected and analyzed.

RESULTS

Our study showed that genetic polymorphisms of maternal MTHFR gene at rs4846052 and rs1801131 were significantly associated with risk of CHD in the homozygote comparisons (TT vs. CC at rs4846052: OR = 7.62 [95%CI 2.95-19.65]; GG vs. TT at rs1801131: OR = 5.18 [95%CI 2.77-9.71]). And six haplotypes of G-C (involving rs4846048 and rs2274976), A-C (involving rs1801133 and rs4846052), G-T (involving rs1801133 and rs4846052), G-T-G (involving rs2066470, rs3737964 and rs535107), A-C-G (involving rs2066470, rs3737964 and rs535107) and G-C-G (involving rs2066470, rs3737964 and rs535107) were identified to be significantly associated with risk of CHD. Additionally, we observed that a two-locus model involving rs2066470 and rs1801131 as well as a three-locus model involving rs227497, rs1801133 and rs1801131 were significantly associated with risk of CHD in the gene-gene interaction analyses. For three subtypes including atrial septal defect, ventricular septal defect and patent ductus arteriosus, similar results were observed.

CONCLUSIONS

Our study indicated genetic polymorphisms of maternal MTHFR gene were significantly associated with risk of fetal CHD in the Chinese population. Additionally, there were significantly interactions among different SNPs on risk of CHD. However, how these SNPs affect the development of fetal heart remains unknown, and more studies in different ethnic populations and with a larger sample are required to confirm these findings.

Patent Foramen Ovale-A Not So Innocuous Septal Atrial Defect in Adults

Patent foramen ovale (PFO) is a common congenital atrial septal defect with an incidence of 15–35% in the adult population. The development of the interatrial septum is a process that begins in the fourth gestational week and is completed only after birth. During intrauterine life, the foramen ovale allows the passage of highly oxygenated blood from the right to the left atrium and into the systemic arteries, thus bypassing the pulmonary circulation. In 75% of the general population, the foramen ovale closes after birth, and only an oval depression, called fossa ovalis, remains on the right side of the interatrial septum. Patent foramen ovale can be associated with various clinically important conditions, including migraine and stroke, or decompression illness in divers. The aim of this review is to summarize the PFO developmental and anatomical features and to discuss the clinical risks associated with this atrial septal defect in adults.

Mending a broken heart: In vitro, in vivo and in silico models of congenital heart disease

Birth defects contribute to ∼0.3% of global infant mortality in the first month of life, and congenital heart disease (CHD) is the most common birth defect among newborns worldwide. Despite the significant impact on human health, most treatments available for this heterogenous group of disorders are palliative at best. For this reason, the complex process of cardiogenesis, governed by multiple interlinked and dose-dependent pathways, is well investigated. Tissue, animal and, more recently, computerized models of the developing heart have facilitated important discoveries that are helping us to understand the genetic, epigenetic and mechanobiological contributors to CHD aetiology. In this Review, we discuss the strengths and limitations of different models of normal and abnormal cardiogenesis, ranging from single-cell systems and 3D cardiac organoids, to small and large animals and organ-level computational models. These investigative tools have revealed a diversity of pathogenic mechanisms that contribute to CHD, including genetic pathways, epigenetic regulators and shear wall stresses, paving the way for new strategies for screening and non-surgical treatment of CHD. As we discuss in this Review, one of the most-valuable advances in recent years has been the creation of highly personalized platforms with which to study individual diseases in clinically relevant settings.

Burden and consequence of birth defects in Nepal-evidence from prospective cohort study

Background

Every year an estimated 7.9 million babies are born with birth defect. Of these babies, more than 3 million die and 3.2 million have disability. Improving nationwide information on prevalence of birth defect, risk factor and consequence is required for better resource allocation for prevention, management and rehabilitation. In this study, we assess the prevalence of birth defect, associated risk factors and consequences in Nepal.

Method

This is a prospective cohort study conducted in 12 hospitals of Nepal for 18 months. All the women who delivered in the hospitals during the study period was enrolled. Independent researchers collected data on the social and demographic information using semi-structured questionnaire at the time of discharge and clinical events and birth outcome information from the clinical case note. Data were analyzed on the prevalence and type of birth defect. Logistic regression was done to assess the risk factor and consequences for birth defect.

Results

Among the total 87,242 livebirths, the prevalence of birth defects was found to be 5.8 per 1000 live births. The commonly occurring birth defects were anencephaly (3.95%), cleft lip (2.77%), cleft lip and palate (6.13%), clubfeet (3.95%), eye abnormalities (3.95%) and meningomyelocele (3.36%). The odds of birth defect was higher among mothers with age < 20 years (adjusted Odds ratio (aOR) 1.64; 95% CI, 1.18–2.28) and disadvantaged ethnicity (aOR 1.78; 95% CI, 1.46–2.18). The odds of birth asphyxia was twice fold higher among babies with birth defect (aOR 1.88; 95% CI, 1.41–2.51) in reference with babies without birth defect. The odds of neonatal infection was twice fold higher among babies with birth defect (aOR 1.82; 95% CI, 1.12–2.96) in reference with babies without birth defect. Babies with birth defect had three-fold risk of pre-discharge mortality (aOR 3.00; 95% CI, 1.93–4.69).

Conclusion

Maternal age younger than 20 years and advantaged ethnicity were risk factors of birth defects. Babies with birth defect have high risk for birth asphyxia, neonatal infection and pre-discharge mortality at birth. Further evaluation on the care provided to babies who have birth defect is warranted.

Funding

Swedish Research Council (VR).

[Congenital ocular anomalies at the University Hospital Campus in Lomé, Togo]

Introduction

les anomalies congénitales oculaires sont des entités cliniques rares dans le monde. Le but de cette étude est de décrire les aspects épidémiologiques et cliniques des anomalies congénitales oculaires au Centre Hospitalier Universitaire-Campus de Lomé.

Méthodes

une étude rétrospective a été réalisée de janvier 2016 à décembre 2018 (3 ans) dans le service d´ophtalmologie du Centre Hospitalier Universitaire-Campus de Lomé. Elle a concerné les enfants porteurs d´anomalies congénitales oculaires. Les variables d´étude ont été: le sexe; l´âge au moment du diagnostic; le type d´anomalies congénitales oculaires; la latéralité.

Résultats

sur 2621 enfants examinés durant la période d´étude, 103 (3,9%) étaient porteurs d´anomalies congénitales oculaires. Des 103 patients, il y avait 60 (58,2%) garçons et 43 (41,8%) filles. L´âge moyen de diagnostic était de 16 ± 5,2 mois (extrêmes: 1 mois et 5 ans). L´anomalie congénitale oculaire la plus fréquente était la cataracte (53,4 %). Les atteintes unilatérales étaient prépondérantes (56,3%). Les anomalies congénitales oculaires étaient: isolées (82,5%) ; associées aux anomalies systémiques (11,7%); associées entre elles (5,8%).

Conclusion

ces résultats indiquent que les caractéristiques épidémiologiques et cliniques des anomalies congénitales oculaires se rapprochent de celles rapportées dans la littérature. Cependant, dans notre milieu, la fréquence des anomalies congénitales oculaires et l´âge de diagnostic sont élevés. Il est important de diagnostiquer tôt les anomalies congénitales oculaires dans le but d´assurer la prise en charge et de préserver la fonction visuelle.

Identifying environmental risk factors and gene-environment interactions in holoprosencephaly

BACKGROUND

Holoprosencephaly is the most common malformation of the forebrain (1 in 250 embryos) with severe consequences for fetal and child development. This study evaluates nongenetic factors associated with holoprosencephaly risk, severity, and gene-environment interactions.

METHODS

For this retrospective case control study, we developed an online questionnaire focusing on exposures to common and rare toxins/toxicants before and during pregnancy, nutritional factors, maternal health history, and demographic factors. Patients with holoprosencephaly were primarily ascertained from our ongoing genetic and clinical studies of holoprosencephaly. Controls included children with Williams-Beuren syndrome (WBS) ascertained through online advertisements in a WBD support group and fliers.

RESULTS

Difference in odds of exposures between cases and controls as well as within cases with varying holoprosencephaly severity were studied. Cases included children born with holoprosencephaly (n = 92) and the control group consisted of children with WBS (n = 56). Pregnancy associated risk associated with holoprosencephaly included maternal pregestational diabetes (9.2% of cases and 0 controls, p = .02), higher alcohol consumption (adjusted odds ratio [aOR], 1.73; 95% CI, 0.88-15.71), and exposure to consumer products such as aerosols or sprays including hair sprays (aOR, 2.46; 95% CI, 0.89-7.19). Significant gene-environment interactions were identified including for consumption of cheese (p < .05) and espresso drinks (p = .03).

CONCLUSION

The study identifies modifiable risk factors and gene-environment interactions that should be considered in future prevention of holoprosencephaly. Studies with larger HPE cohorts will be needed to confirm these findings.

Case-Parent Trio Studies in Cleft Lip and Palate

Cleft lip with or without cleft palate (CL/P) is one of the most common congenital malformations in humans involving various genetic and environmental risk factors. The prevalence of CL/P varies according to geographical location, ethnicity, race, gender, and socioeconomic status, affecting approximately 1 in 800 live births worldwide. Genetic studies aim to understand the mechanisms contributory to a phenotype by measuring the association between genetic variants and also between genetic variants and phenotype population. Genome-wide association studies are standard tools used to discover genetic loci related to a trait of interest. Genetic association studies are generally divided into two main design types: population-based studies and family-based studies. The epidemiological population-based studies comprise unrelated individuals that directly compare the frequency of genetic variants between (usually independent) cases and controls. The alternative to population-based studies (case-control designs) includes various family-based study designs that comprise related individuals. An example of such a study is a case-parent trio design study, which is commonly employed in genetics to identify the variants underlying complex human disease where transmission of alleles from parents to offspring is studied. This article describes the fundamentals of case-parent trio study, trio design and its significances, statistical methods, and limitations of the trio studies.

Impact of Maternal Smoking on Nonsyndromic Clefts: Sex-Specific Associations With Side and Laterality

OBJECTIVE

To compare the incidence of right-sided versus left-sided, and unilateral versus bilateral, nonsyndromic clefting in the affected offspring of smoking and nonsmoking mothers.

DESIGN

Self-report data on periconceptual and first trimester smoking behavior were collected from 842 mothers of children with nonsyndromic orofacial clefting. Differences in the incidence of left- versus right-sided clefts, and of unilateral versus bilateral clefts, were analyzed between the children of smoking and nonsmoking mothers.

SETTING

Interviews and clinical examinations took place at 8 specialist centers in Germany.

PATIENTS AND PARTICIPANTS

Children with nonsyndromic clefts were recruited during the course of surgical or orthodontic treatment, or within the context of the annual control consultation. Patients with cleft palate only or missing data were excluded. The final cohort comprised 842 patients (540 males and 302 females) with unilateral or bilateral clefts. The respective mothers were interviewed.

MAIN OUTCOME MEASURE

Side and laterality of nonsyndromic clefts were the main outcome measures.

RESULTS

Children of smoking mothers more often had right-sided clefts than children of nonsmoking mothers (42% right-sided clefts in children of smoking mothers vs 31% of nonsmoking mothers). Children of smoking mothers more often had bilateral clefts than children of nonsmoking mothers (35% bilateral clefts in children of smoking mothers vs 29% of nonsmoking mothers). Sex-specific analyses confirmed substantially and statistically significant associations only for girls.

CONCLUSIONS

The results suggest that maternal smoking is a sex-specific, exogenous determinant of laterality and side in nonsyndromic clefts.

Prenatal exposure to pesticides and risk for holoprosencephaly: a case-control study

BACKGROUND

Pesticide exposure during susceptible windows and at certain doses are linked to numerous birth defects. Early experimental evidence suggests an association between active ingredients in pesticides and holoprosencephaly (HPE), the most common malformation of the forebrain in humans (1 in 250 embryos). No human studies to date have examined the association. This study investigated pesticides during multiple windows of exposure and fetal risk for HPE. It is hypothesized that pre-conception and early pregnancy, the time of brain development in utero, are the most critical windows of exposure.

METHODS

A questionnaire was developed for this retrospective case-control study to estimate household, occupational, and environmental pesticide exposures. Four windows of exposure were considered: preconception, early, mid and late pregnancy. Cases were identified through the National Human Genome Research Institute's ongoing clinical studies of HPE. Similarly, controls were identified as children with Williams-Beuren syndrome, a genetic syndrome also characterized by congenital malformations, but etiologically unrelated to HPE. We assessed for differences in odds of exposures to pesticides between cases and controls.

RESULTS

Findings from 91 cases and 56 controls showed an increased risk for HPE with reports of maternal exposure during pregnancy to select pesticides including personal insect repellants (adjusted odds ratio (aOR) 2.89, confidence interval (CI): 0.96-9.50) and insecticides and acaricides for pets (aOR 3.84, CI:1.04-16.32). Exposure to household pest control products during the preconception period or during pregnancy was associated with increased risk for HPE (aOR 2.60, OR: 0.84-8.68). No associations were found for occupational exposures to pesticides during pregnancy (aOR: 1.15, CI: 0.11-11.42), although exposure rates were low. Higher likelihood for HPE was also observed with residency next to an agricultural field (aOR 3.24, CI: 0.94-12.31).

CONCLUSIONS

Observational findings are consistent with experimental evidence and suggest that exposure to personal, household, and agricultural pesticides during pregnancy may increase risk for HPE. Further investigations of gene by environment interactions are warranted.

NAD deficiency due to environmental factors or gene-environment interactions causes congenital malformations and miscarriage in mice

Causes for miscarriages and congenital malformations can be genetic, environmental, or a combination of both. Genetic variants, hypoxia, malnutrition, or other factors individually may not affect embryo development, however, they may do so collectively. Biallelic loss-of-function variants in HAAO or KYNU, two genes of the nicotinamide adenine dinucleotide (NAD) synthesis pathway, are causative of congenital malformation and miscarriage in humans and mice. The variants affect normal embryonic development by disrupting the synthesis of NAD, a key factor in multiple biological processes, from its dietary precursor tryptophan, resulting in NAD deficiency. This study demonstrates that congenital malformations caused by NAD deficiency can occur independent of genetic disruption of NAD biosynthesis. C57BL/6J wild-type mice had offspring exhibiting similar malformations when their supply of the NAD precursors tryptophan and vitamin B3 in the diet was restricted during pregnancy. When the dietary undersupply was combined with a maternal heterozygous variant in Haao, which alone does not cause NAD deficiency or malformations, the incidence of embryo loss and malformations was significantly higher, suggesting a gene-environment interaction. Maternal and embryonic NAD levels were deficient. Mild hypoxia as an additional factor exacerbated the embryo outcome. Our data show that NAD deficiency as a cause of embryo loss and congenital malformation is not restricted to the rare cases of biallelic mutations in NAD synthesis pathway genes. Instead, monoallelic genetic variants and environmental factors can result in similar outcomes. The results expand our understanding of the causes of congenital malformations and the importance of sufficient NAD precursor consumption during pregnancy.

Genetic Contribution to Congenital Heart Disease (CHD)

Congenital heart defects (CHD) are the most common congenital problems in neonates. The basis for CHD is multifactorial, involving genetic and environmental components. The elucidation of genetic components remains difficult because it is a genetically heterogeneous disease. Currently, the major identified genetic causes include chromosomal abnormalities, large subchromosomal deletions/duplications, and point mutations. However, much more remains to be unraveled. An important insight from the research on the genetics of CHD is that any change at the genetic level that alters the dosage of genes required in any process during heart development results in a developmental defect. The use of conventional gene identification (linkage analysis and direct targeted sequencing) methods followed by the rapid advancements in high-throughput technologies (copy number variant platforms, SNP arrays, and next-generation sequencing) has identified an extensive list of genetic causes. However, the most common presentation of CHD is in the form of sporadic cases. Therefore, it is important to identify their underlying genetic cause. In this review, we revisit the causal genetic factors of CHD and discuss the clinical implications of research in the field.

Gene-environment interaction impacts on heart development and embryo survival

Congenital heart disease (CHD) is the most common type of birth defect. In recent years, research has focussed on identifying the genetic causes of CHD. However, only a minority of CHD cases can be attributed to single gene mutations. In addition, studies have identified different environmental stressors that promote CHD, but the additive effect of genetic susceptibility and environmental factors is poorly understood. In this context, we have investigated the effects of short-term gestational hypoxia on mouse embryos genetically predisposed to heart defects. Exposure of mouse embryos heterozygous for Tbx1 or Fgfr1/Fgfr2 to hypoxia in utero increased the incidence and severity of heart defects while Nkx2-5^+/- embryos died within 2 days of hypoxic exposure. We identified the molecular consequences of the interaction between Nkx2-5 and short-term gestational hypoxia, which suggest that reduced Nkx2-5 expression and a prolonged hypoxia-inducible factor 1α response together precipitate embryo death. Our study provides insight into the causes of embryo loss and variable penetrance of monogenic CHD, and raises the possibility that cases of foetal death and CHD in humans could be caused by similar gene-environment interactions.

Developmental processes regulate craniofacial variation in disease and evolution

Variation in development mediates phenotypic differences observed in evolution and disease. Although the mechanisms underlying phenotypic variation are still largely unknown, recent research suggests that variation in developmental processes may play a key role. Developmental processes mediate genotype-phenotype relationships and consequently play an important role regulating phenotypes. In this review, we provide an example of how shared and interacting developmental processes may explain convergence of phenotypes in spliceosomopathies and ribosomopathies. These data also suggest a shared pathway to disease treatment. We then discuss three major mechanisms that contribute to variation in developmental processes: genetic background (gene-gene interactions), gene-environment interactions, and developmental stochasticity. Finally, we comment on evolutionary alterations to developmental processes, and the evolution of disease buffering mechanisms.

Early Gestational Hypoxia and Adverse Developmental Outcomes

Hypoxia is a normal and essential part of embryonic development. However, this state may leave the embryo vulnerable to damage when oxygen supply is disturbed. Embryofetal response to hypoxia is dependent on duration and depth of hypoxia, as well as developmental stage. Early postimplantation rat embryos were resilient to hypoxia, with many surviving up to 1.5 hr of uterine clamping, while most mid-gestation embryos were dead after 1 hour of clamping. Survivors were small and many had a range of defects, principally terminal transverse limb reduction defects. Similar patterns of malformations occurred when embryonic hypoxia was induced by maternal hypoxia, interruption of uteroplacental flow, or perfusion and embryonic bradycardia. There is good evidence that high altitude pregnancies are associated with smaller babies and increased risk of some malformations, but these results are complicated by increased risk of pre-eclampsia. Early onset pre-eclampsia itself is associated with small for dates and increased risk of atrio-ventricular septal defects. Limb defects have clearly been associated with chorionic villus sampling, cocaine, and misoprostol use. Similar defects are also observed with increased frequency among fetuses who are homozygous for thalassemia. Drugs that block the potassium current, whether as the prime site of action or as a side effect, are highly teratogenic in experimental animals. They induce embryonic bradycardia, hypoxia, hemorrhage, and blisters, leading to transverse limb defects as well as craniofacial and cardiovascular defects. While evidence linking these drugs to birth defects in humans is not compelling, the reason may methodological rather than biological. Birth Defects Research 109:1358-1376, 2017.© 2017 Wiley Periodicals, Inc.

Congenital heart defects according to the types of the risk factors - a single center experience

Objective: The main aim of this study was to compare the prevalence of congenital heart defects (CHDs) between pregnant women with and those without the risk factors. The secondary aim was to determine the influence of the specific risk factors, divided into subgroups, on the development of the CHD. Methods: The presented results were obtained over the course of a 15-year study between years 2002 and 2016. Fetal echocardiography was performed as a planned screening examination during the second trimester of gravidity. A total of 35,831 singleton pregnancies were examined at our center. Risk factors for the development of CHDs were analyzed and divide into the following groups: (i) maternal age ≥35 years; (ii) mother-related risk factors; (iii) pregnancy- and fetus-related risk factors; (iv) pregnancy after in vitro fertilization (IVF); (v) history of CHDs in the first-degree family member; (vi) history of CHDs in the second-degree family member; and (vii) positive genetic family history. Results: The risk factors were identified in 25% (8990/35,831) of pregnancies. In total, CHDs were detected in 1.1% (394/35,831) of fetuses. The prevalence rate of CHDs was higher in the pregnancies with than in those without the risk factors (2.5% [221/8990] versus 0.6% [173/26,841]; p < .0001). The presence of pregnancy- and fetus-related risk factors (odds ratio [OR], 6.5; 95% confidence interval [CI], 4.3-9.7) and pregnancy after IVF (OR, 2.8; 95% CI, 1.5-5.2) were found to be independent risk factors of CHDs. Conclusions: The presence of specific risk factors is related to the increasing prevalence of CHDs. Pregnancy- and fetus-related risk factors and in vitro fertilization were found to be the independent risk factors of CHD.

Prenatal chromosomal microarray analysis in fetuses with congenital heart disease: a prospective cohort study

BACKGROUND

Currently, chromosomal microarray analysis is considered the first-tier test in pediatric care and prenatal diagnosis. However, the diagnostic yield of chromosomal microarray analysis for prenatal diagnosis of congenital heart disease has not been evaluated based on a large cohort.

OBJECTIVE

Our aim was to evaluate the clinical utility of chromosomal microarray as the first-tier test for chromosomal abnormalities in fetuses with congenital heart disease.

STUDY DESIGN

In this prospective study, 602 prenatal cases of congenital heart disease were investigated using single nucleotide polymorphism array over a 5-year period.

RESULTS

Overall, pathogenic chromosomal abnormalities were identified in 125 (20.8%) of 602 prenatal cases of congenital heart disease, with 52.0% of them being numerical chromosomal abnormalities. The detection rates of likely pathogenic copy number variations and variants of uncertain significance were 1.3% and 6.0%, respectively. The detection rate of pathogenic chromosomal abnormalities in congenital heart disease plus additional structural anomalies (48.9% vs 14.3%, P < .0001) or intrauterine growth retardation group (50.0% vs 14.3%, P = .044) was significantly higher than that in isolated congenital heart disease group. Additionally, the detection rate in congenital heart disease with additional structural anomalies group was significantly higher than that in congenital heart disease with soft markers group (48.9% vs 19.8%, P < .0001). No significant difference was observed in the detection rates between congenital heart disease with additional structural anomalies and congenital heart disease with intrauterine growth retardation groups (48.9% vs 50.0%), congenital heart disease with soft markers and congenital heart disease with intrauterine growth retardation groups (19.8% vs 50.0%), or congenital heart disease with soft markers and isolated congenital heart disease groups (19.8% vs 14.3%). The detection rate in fetuses with congenital heart disease plus mild ventriculomegaly was significantly higher than in those with other types of soft markers (50.0% vs 15.6%, P < .05).

CONCLUSION

Our study suggests chromosomal microarray analysis is a reliable and high-resolution technology and should be used as the first-tier test for prenatal diagnosis of congenital heart disease in clinical practice.

Clinical and risk factor analysis of cloacal defects in the National Birth Defects Prevention Study

Cloacal exstrophy (CE) and persistent cloaca (PC) (alternatively termed urorectal septum malformation sequence [URSMS]), represent two major cloacal defects (CDs). Clinical characteristics and risk factors often are studied for both defects combined, rather than exploring if these defects have different etiologies. We enumerated clinical features for 47 CE and 54 PC (inclusive of URSMS) cases from the National Birth Defects Prevention Study. Thirty-three CE cases were classified as isolated and 14 as multiple (presence of unassociated major defects); respective totals for PC cases were 26 and 28. We compared selected child and maternal characteristics between 11,829 non-malformed controls and CE and PC cases using chi-square or Fisher's exact tests. Compared to controls, CE and PC cases were statistically more likely (p < 0.05) to be preterm; CE cases were more likely to be multiple births. We conducted logistic regression analysis to estimate odds ratios and 95% confidence intervals for any CD, CE, and PC with selected self-reported maternal prepregnancy and periconceptional (one month prior to 3 months following conception) exposures. In crude and adjusted analyses, we observed significant positive associations for any CD, CE, and PC with use of any fertility medication or assisted reproductive technology procedure. Significant positive associations observed only in crude analyses were any CD with maternal obesity or use of progesterone, any CD and CE with any x-ray, and any CD and PC with use of folate antagonist medications. Our findings provide some of the first insights into potential differing etiologies for CE and PC.

Epigenetic mechanisms underlying maternal diabetes-associated risk of congenital heart disease

Birth defects are the leading cause of infant mortality, and they are caused by a combination of genetic and environmental factors. Environmental risk factors may contribute to birth defects in genetically susceptible infants by altering critical molecular pathways during embryogenesis, but experimental evidence for gene-environment interactions is limited. Fetal hyperglycemia associated with maternal diabetes results in a 5-fold increased risk of congenital heart disease (CHD), but the molecular basis for this correlation is unknown. Here, we show that the effects of maternal hyperglycemia on cardiac development are sensitized by haploinsufficiency of Notch1, a key transcriptional regulator known to cause CHD. Using ATAC-seq, we found that hyperglycemia decreased chromatin accessibility at the endothelial NO synthase (Nos3) locus, resulting in reduced NO synthesis. Transcription of Jarid2, a regulator of histone methyltransferase complexes, was increased in response to reduced NO, and this upregulation directly resulted in inhibition of Notch1 expression to levels below a threshold necessary for normal heart development. We extended these findings using a Drosophila maternal diabetic model that revealed the evolutionary conservation of this interaction and the Jarid2-mediated mechanism. These findings identify a gene-environment interaction between maternal hyperglycemia and Notch signaling and support a model in which environmental factors cause birth defects in genetically susceptible infants.

Observed prevalence and risk factors of birth defects in Shanghai, China

AIM

To investigate the prevalence and related risk factors of birth defects in Shanghai.

METHODS

This report describes a population-based study of all births at the Obstetrics and Gynecology Hospital of Fudan University in Shanghai, China from January 2008 to December 2014. A logistic regression analysis was used to identify the parameters that are independently associated with birth defects.

RESULTS

A total of 82814 births, including 824 cases of birth defects, were recorded. The rate of birth defects was 0.995 per 100 births. In the multivariable regression analysis, neonatal birth defects were likely to be associated with higher gravidity [odds ratio (OR), 1.099, 95%CI: 1.024-1.178], premature birth (OR = 1.905, 95%CI: 1.501-2.418), low birth weight (OR = 3.844, 95%CI: 3.004-4.919), twin births or higher order multiple pregnancies (OR = 1.477, 95%CI: 1.107-1.969), cesarean delivery (OR = 1.184, 95%CI: 1.016-1.380) and registration as part of a migrant population (OR = 1.380, 95%CI: 1.167-1.632). Female infants were less likely to have birth defects than male infants (OR = 0.710, 95%CI: 0.616-0.818).

CONCLUSION

Higher gravidity, premature birth, lower birth weight, twin births or higher order multiple pregnancies, and registration as part of a migrant population are independent predictors of birth defects.

The 22q11.2 Deletion Syndrome in Congenital Heart Defects: Prevalence of Microdeletion Syndrome in Cameroon

BACKGROUND

The 22q11.2 deletion syndrome is amongst the most common microdeletion syndrome in humans. Its prevalence remains unknown in sub-Saharan Africa, and its clinical features are under-reported for people of African descent.

OBJECTIVE

We have investigated the prevalence of the 22q11.2 deletion syndrome in patients with congenital heart defects in Cameroon.

METHODS

A total of 70 of 100 cases of congenital cardiac malformation with echocardiographic evidence were examined prospectively and tested for the 22q11.2 deletion, using multiplex ligation-dependent probe amplification and fluorescence in situ hybridization.

RESULTS

Two of 70 patients (2.8%) were found to have 22q11.2 deletion. Both cases had conotruncal heart defects and exhibited extracardiac features of the 22q11.2 deletion syndrome that were either classical (e.g., puffy upper eyelids, bulbous tip of the nose) or less identifiable (telecanthus, hooding of eyelids and prominent nasal bridge).

CONCLUSIONS

The report shows that the prevalence of the 22q11.2 deletion syndrome in patients with heart malformations in Cameroon (2.8%) is similar to that of various world populations. The clinical phenotypes will contribute to the Global Atlas for dysmorphology. "Omics" technologies offer much promise in genetic/genomic screening of severe global health problems.

Determinants of orofacial clefting II: Effects of 5-Aza-2'-deoxycytidine on gene methylation during development of the first branchial arch

Defects in development of the secondary palate, which arise from the embryonic first branchial arch (1-BA), can cause cleft palate (CP). Administration of 5-Aza-2'-deoxycytidine (AzaD), a demethylating agent, to pregnant mice on gestational day 9.5 resulted in complete penetrance of CP in fetuses. Several genes critical for normal palatogenesis were found to be upregulated in 1-BA, 12h after AzaD exposure. MethylCap-Seq (MCS) analysis identified several differentially methylated regions (DMRs) in DNA extracted from AzaD-exposed 1-BAs. Hypomethylated DMRs did not correlate with the upregulation of genes in AzaD-exposed 1-BAs. However, most DMRs were associated with endogenous retroviral elements. Expression analyses suggested that interferon signaling was activated in AzaD-exposed 1-BAs. Our data, thus, suggest that a 12-h in utero AzaD exposure demethylates and activates endogenous retroviral elements in the 1-BA, thereby triggering an interferon-mediated response. This may result in the dysregulation of key signaling pathways during palatogenesis, causing CP.

Determinants of orofacial clefting I: Effects of 5-Aza-2'-deoxycytidine on cellular processes and gene expression during development of the first branchial arch

In this study, we identify gene targets and cellular events mediating the teratogenic action(s) of 5-Aza-2'-deoxycytidine (AzaD), an inhibitor of DNA methylation, on secondary palate development. Exposure of pregnant mice (on gestation day (GD) 9.5) to AzaD for 12h resulted in the complete penetrance of cleft palate (CP) in fetuses. Analysis of cells of the embryonic first branchial arch (1-BA), in fetuses exposed to AzaD, revealed: 1) significant alteration in expression of genes encoding several morphogenetic factors, cell cycle inhibitors and regulators of apoptosis; 2) a decrease in cell proliferation; and, 3) an increase in apoptosis. Pyrosequencing of selected genes, displaying pronounced differential expression in AzaD-exposed 1-BAs, failed to reveal significant alterations in CpG methylation levels in their putative promoters or gene bodies. CpG methylation analysis suggested that the effects of AzaD on gene expression were likely indirect.

Congenital heart diseases and their association with the variant distribution features on susceptibility genes

Congenital heart disease (CHD), one of the causes of childhood morbidity and mortality, is mainly triggered by a combination of environmental and genetic factors. Several susceptible genes, such as NKX2-5, GATA4 and TBX5, have been reported as closely related to heart and vessel development. CHD subtypes are classified into diverse clinical phenotypes, such as atrial septal defects (ASD), ventricular septal defects (VSD), tetralogy of Fallot (TOF), and Holt-Oram syndrome (HOS). Here, we summarize the associations of the genetic variants in these three genes with CHD subtypes. CHD-associated variants of NKX2-5 locate mainly in the tinman domain and the homeodomain. Mutations in the homeodomain are correlated with ASD and atrioventricular (AV) block subtypes. VSD-associated variants of GATA4 are mainly at its terminal ends. Variants of TBX5 gene are primarily in exons 3, 4, 5 and 7 and highly associated with HOS subtype. Hence, the variant distribution of NKX2-5, GATA4 and TBX5 are tightly associated with particular CHD subtypes. Further structure-modelling analysis revealed that these mutated amino acid residuals maintain their DNA-binding ability and structural stability. Therefore structural features of these genes may be used to predict the high risk of CHD subtypes in infants.

A Biobank for Long-term and Sustainable Research in the Field of Congenital Heart Disease in Germany

Congenital heart disease (CHD) is the most frequent birth defect (0.8%-1% of all live births). Due to the advance in prenatal and postnatal early diagnosis and treatment, more than 90% of these patients survive into adulthood today. However, several mid- and long-term morbidities are dominating the follow-up of these patients. Due to the rarity and heterogeneity of the phenotypes of CHD, multicenter registry-based studies are required. The CHD-Biobank was established in 2009 with the aim to collect DNA from patients and their parents (trios) or from affected families, as well as cardiovascular tissues from patients undergoing corrective heart surgery for cardiovascular malformations. Clinical/phenotype data are matched to the International Paediatric and Congenital Cardiac Code (IPCCC) and the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10). The DNA collection currently comprises samples from approximately 4200 participants with a wide range of CHD phenotypes. The collection covers about 430 trios and 120 families with more than one affected member. The cardiac tissue collection comprises 1143 tissue samples from 556 patients after open heart surgery. The CHD-Biobank provides a comprehensive basis for research in the field of CHD with high standards of data privacy, IT management, and sample logistics.

Advances in the Study of Heart Development and Disease Using Zebrafish

Animal models of cardiovascular disease are key players in the translational medicine pipeline used to define the conserved genetic and molecular basis of disease. Congenital heart diseases (CHDs) are the most common type of human birth defect and feature structural abnormalities that arise during cardiac development and maturation. The zebrafish, Danio rerio, is a valuable vertebrate model organism, offering advantages over traditional mammalian models. These advantages include the rapid, stereotyped and external development of transparent embryos produced in large numbers from inexpensively housed adults, vast capacity for genetic manipulation, and amenability to high-throughput screening. With the help of modern genetics and a sequenced genome, zebrafish have led to insights in cardiovascular diseases ranging from CHDs to arrhythmia and cardiomyopathy. Here, we discuss the utility of zebrafish as a model system and summarize zebrafish cardiac morphogenesis with emphasis on parallels to human heart diseases. Additionally, we discuss the specific tools and experimental platforms utilized in the zebrafish model including forward screens, functional characterization of candidate genes, and high throughput applications.

Gene-Environment Interactions and the Etiology of Birth Defects

It is thought that most structural birth defects are caused by a complex combination of genetic and environmental factors that interact to interfere with morphogenetic processes. It is important not only to identify individual genetic and environmental risk factors for particular defects but also to identify which environmental factors interact specifically with which genetic variants that predispose to the same defect. Genomic and epidemiological studies are critical to this end. Development and analysis of model systems will also be essential for this goal, as well as for understanding the mechanisms that underlie specific gene-environment interactions.

Genetics of Congenital Heart Defects: The NKX2-5 Gene, a Key Player

Congenital heart defects (CHDs) represent the biggest fraction of morbid congenital anomalies worldwide. Owing to their complex inheritance patterns and multifactorial etiologies, these defects are difficult to identify before complete manifestation. Research over the past two decades has established firmly the role of genetics in the development of these congenital defects. While syndromic CHDs are more straightforward, non-syndromic CHDs are usually characterized by multiple mutations that affect intricate inter-connected developmental pathways. Knock-out and gene expression studies in mice and other genetic models have been performed to elucidate the roles of these implicated genes. Functional analysis has not been able to resolve the complete picture, as increasingly more downstream effects are continuously being assigned to CHD mutant factors. NKX2-5, a cardiac transcription factor, has received much attention for its role in cardiac dysmorphogenesis. Approximately 50 different mutations in this gene have been identified to date, and only a few have been functionally characterized. The mutant NKX2-5 factor can regulate a number of off-targets downstream to facilitate CHD development. This review summarizes the genetic etiology of congenital heart defects and emphasizes the need for NKX2-5 mutation screening.

Using frogs faces to dissect the mechanisms underlying human orofacial defects

In this review I discuss how Xenopus laevis is an effective model to dissect the mechanisms underlying orofacial defects. This species has been particularly useful in studying the understudied structures of the developing face including the embryonic mouth and primary palate. The embryonic mouth is the first opening between the foregut and the environment and is critical for adult mouth development. The final step in embryonic mouth formation is the perforation of a thin layer of tissue covering the digestive tube called the buccopharyngeal membrane. When this tissue does not perforate in humans it can pose serious health risks for the fetus and child. The primary palate forms just dorsal to the embryonic mouth and in non-amniotes it functions as the roof of the adult mouth. Defects in the primary palate result in a median oral cleft that appears similar across the vertebrates. In humans, these median clefts are often severe and surgically difficult to repair. Xenopus has several qualities that make it advantageous for craniofacial research. The free living embryo has an easily accessible face and we have also developed several new tools to analyze the development of the region. Further, Xenopus is readily amenable to chemical screens allowing us to uncover novel gene-environment interactions during orofacial development, as well as to define underlying mechanisms governing such interactions. In conclusion, we are utilizing Xenopus in new and innovative ways to contribute to craniofacial research.