Proportion of neural tube defects attributable to known risk factors

Characteristics and Outcomes of Patients With Spina Bifida in Texas by Patient Age

INTRODUCTION

Spina bifida (SB) occurs in 3.5/10,000 live births and is associated with significant long-term neurologic and urologic morbidity. We explored the characteristics and outcomes of pediatric patients with SB and the facilities that treat them in Texas.

METHODS

We retrospectively reviewed a statewide hospital inpatient discharge database (2013-2021) to identify patients aged <18 y with SB using International Classification of Diseases 9/10 codes. Patients transferred to outside hospitals were excluded to avoid double-counting. Descriptive statistics and chi-square test were performed.

RESULTS

Seven thousand five hundred thirty one inpatient hospitalizations with SB were analyzed. Most SB care is provided by a few facilities. Two facilities (1%) averaged >100 SB admissions per year (33% of patients), while 15 facilities (8%) treat 10-100 patients per year (51% of patients). Most facilities (145/193, 75%) average less than one patient per year. Infants tended to be sicker (17% extreme illness severity, P < 0.001). Overall mortality is low (1%), primarily occurring in the neonatal period (8%, P < 0.001). Most admissions are associated with surgical intervention, with 63% of encounters having operating room charges with an average cost of $25,786 ± 24,884. Admissions for spinal procedures were more common among infants, whereas admissions for genitourinary procedures were more common among older patients (P < 0.001). The average length of stay was 8 ± 16 d with infants having the longest length of stay (19 ± 33, P < 0.001).

CONCLUSIONS

Patients have significant long-term health needs with evolving pediatric surgical indications as they grow. Pediatric SB care is primarily provided by a small number of facilities in Texas. Longitudinal care coordination of their multidisciplinary surgical care is needed to optimize patient care.

Proposal for standardized prenatal assessment of fetal open dysraphisms by the European reference network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies (ITHACA) and eUROGEN

Open dysraphisms, that is, myelomeningocele and myeloschisis, are rare diseases associated with a risk of severe disability, including lower limb motor and sensory deficiency, sphincter deficiency, and potential intellectual deficiency. Open dysraphism is diagnosed in Europe in 93.5% of cases. In case of suspicion of fetal open dysraphism, a detailed fetal morphologic assessment is required to confirm the diagnosis and exclude associated structural anomalies, as well as genetic assessment. In case of isolated fetal open dysraphism, assessment of prognosis is based on fetal imaging including the level of the lesion, the presence or not of a sac, the presence and nature of intra cranial anomalies, and the anatomical and functional evaluation of the lower extremities. Based on these biomarkers, a personalized prognosis as well as comprehensive information about prenatal management alternatives will allow parents to decide on further management options. Standardization of prenatal assessment is essential to compare outcomes with benchmark data and make assessment of surgical innovation possible. Herein, we propose a protocol for the standardized ultrasound assessment of fetuses with isolated open dysraphism.

The Importance of Neurosurgical Intervention and Surgical Timing for Management of Pediatric Patients with Myelomeningoceles in Bangladesh

OBJECTIVE

Reports on the management and survival of children with myelomeningocele defects in Bangladesh are limited. This study describes the characteristics and outcomes of these children, focusing on the timing of surgical repair and factors affecting survival.

METHODS

We enrolled patients with myelomeningoceles in a case-control study on arsenic exposure and spina bifida in Bangladesh. Cases were subsequently followed at regular intervals to assess survival. Demographic, clinical, and surgical characteristics were reviewed. Univariate tests identified factors affecting survival.

RESULTS

Between 2016 and 2022, we enrolled 272 patients with myelomeningocele. Postnatal surgical repair was performed in 63% of cases. However, surgery within 5 days after birth was infrequent (<10%) due to delayed presentation, and there was a high rate (29%) of preoperative deaths. Surgical repair significantly improved patient survival (P < 0.0001). Older age at time of surgery was also associated with improved survival rates, which most likely represents that those who survived to older ages prior to surgery accommodated better with their lesions. Patients who presented with ruptured lesions had lower survival rates.

CONCLUSIONS

Timely neurosurgical repair of myelomeningoceles in Bangladesh is hindered by late patient presentation, resulting in a high preoperative patient death rate. Neurosurgical intervention remains a significant predictor of survival. Increased access to neurosurgical care and education of families and non-neurosurgical providers on the need for timely surgical intervention are important for improving the survival of infants with myelomeningoceles.

Epidemiology of neural tube defects in Finland: a nationwide register study 1987-2018

BACKGROUND

Our aim was to evaluate the prevalence, mortality, regional and sex distribution of neural tube defects (NTDs) in Finland.

METHODS

Data for this population-based study were collected from 1987 to 2018 from the national health and social welfare registers.

RESULTS

There were in total 1634 cases of NTDs, of which 511 were live births, 72 pregnancies ended in stillbirth and 1051 were terminations of pregnancy due to fetal anomaly (TOPFA). The total prevalence of NTDs was 8.6 per 10 000 births and it increased slightly annually (OR 1.008; 95% CI: 1.002, 1.013) during the 32-year study period. The birth prevalence of NTDs decreased (OR 0.979; 95% CI: 0.970, 0.987), but the prevalence of TOPFA increased annually (OR 1.024; 95% CI 1.017, 1.031). The perinatal mortality of NTD children was 260.7 per 1000 births and the infant mortality was 184.0 per 1000 live births, whereas these measures in the general population were 4.6 per 1000 births and 3.3 per 1000 live births, respectively. There was no difference in the NTD prevalence between males and females (P-value 0.77). The total prevalence of NTDs varied from 7.1 to 9.4 per 10 000 births in Finland by region.

CONCLUSIONS

Although the majority of NTDs are preventable with an adequate folic acid supplementation, the total prevalence increased in Finland during the study period when folic acid supplementation was mainly recommended to high-risk families and to women with folic acid deficiency. NTDs remain an important cause of infant morbidity and mortality in Finland.

Maternal periconceptional exposure to drinking water disinfection by-products and neural tube defects in offspring

BACKGROUND

Associations between maternal periconceptional exposure to disinfection by-products (DBPs) in drinking water and neural tube defects (NTDs) in offspring are inconclusive, limited in part by exposure misclassification.

METHODS

Maternal interview reports of drinking water sources and consumption from the National Birth Defects Prevention Study were linked with DBP concentrations in public water system monitoring data for case children with an NTD and control children delivered during 2000-2005. DBPs analyzed were total trihalomethanes, the five most common haloacetic acids combined, and individual species. Associations were estimated for all NTDs combined and selected subtypes (spina bifida, anencephaly) with maternal periconceptional exposure to DBPs in public water systems and with average daily periconceptional ingestion of DBPs accounting for individual-level consumption and filtration information. Mixed effects logistic regression models with maternal race/ethnicity and educational attainment at delivery as fixed effects and study site as a random intercept were applied.

RESULTS

Overall, 111 case and 649 control children were eligible for analyses. Adjusted odds ratios for maternal exposure to DBPs in public water systems ranged from 0.8-1.5 for all NTDs combined, 0.6-2.0 for spina bifida, and 0.7-1.9 for anencephaly; respective ranges for average daily maternal ingestion of DBPs were 0.7-1.1, 0.5-1.5, and 0.6-1.8. Several positive estimates (≥1.2) were observed, but all confidence intervals included the null.

CONCLUSIONS

Using community- and individual-level data from a large, US, population-based, case-control study, we observed statistically nonsignificant associations between maternal periconceptional exposure to total and individual DBP species in drinking water and NTDs and subtypes.

A global update on the status of prevention of folic acid-preventable spina bifida and anencephaly in year 2022

BACKGROUND

Mandatory fortification of staple foods with folic acid is an effective public health strategy to prevent folic acid-preventable spina bifida and anencephaly (FAP SBA). We estimated the global proportion of FAP SBA prevented through mandatory folic acid fortification of cereal grains (i.e., wheat flour, maize flour, and rice).

METHODS

We used year 2022 data from the Food Fortification Initiative to identify countries (n = 69) with mandatory fortification of grains that includes folic acid. Sixty-eight countries were eligible for analysis with complete data. Proportion of FAP SBA prevention was modeled assuming >150 mcg/day of folic acid fortification protects against FAP SBA, reducing post-fortification prevalence to a lowest achievable level of 0.5 cases per 1000 births.

RESULTS

Our analysis found that a total of 63,520 cases of FAP SBA were prevented in the year 2022 in 68 countries implementing mandatory folic acid fortification of grains with folic acid. This translated to a 23.7% prevention of all possible FAP SBA prevention globally. An excess of 204,430 cases of FAPSBA still occurred in over 100 countries where mandatory staple food fortification with folic acid is not implemented.

CONCLUSION

Our study showed that only a quarter of all FAP SBA cases were averted through mandatory folic acid fortification in the year 2022; many countries are not implementing the policy, resulting in a large proportion of FAP SBA cases that can be prevented. Fortification will help countries with achieving 2030 Sustainable Development Goals on neonatal- and under-five mortality, disability, stillbirths, and elective terminations prevention, from FAP SBA.

ARMC5 controls the degradation of most Pol II subunits, and ARMC5 mutation increases neural tube defect risks in mice and humans

BACKGROUND

Neural tube defects (NTDs) are caused by genetic and environmental factors. ARMC5 is part of a novel ubiquitin ligase specific for POLR2A, the largest subunit of RNA polymerase II (Pol II).

RESULTS

We find that ARMC5 knockout mice have increased incidence of NTDs, such as spina bifida and exencephaly. Surprisingly, the absence of ARMC5 causes the accumulation of not only POLR2A but also most of the other 11 Pol II subunits, indicating that the degradation of the whole Pol II complex is compromised. The enlarged Pol II pool does not lead to generalized Pol II stalling or a generalized decrease in mRNA transcription. In neural progenitor cells, ARMC5 knockout only dysregulates 106 genes, some of which are known to be involved in neural tube development. FOLH1, critical in folate uptake and hence neural tube development, is downregulated in the knockout intestine. We also identify nine deleterious mutations in the ARMC5 gene in 511 patients with myelomeningocele, a severe form of spina bifida. These mutations impair the interaction between ARMC5 and Pol II and reduce Pol II ubiquitination.

CONCLUSIONS

Mutations in ARMC5 increase the risk of NTDs in mice and humans. ARMC5 is part of an E3 controlling the degradation of all 12 subunits of Pol II under physiological conditions. The Pol II pool size might have effects on NTD pathogenesis, and some of the effects might be via the downregulation of FOLH1. Additional mechanistic work is needed to establish the causal effect of the findings on NTD pathogenesis.

Determinants of neural tube defects among women who gave birth in hospitals in Eastern Ethiopia: evidence from a matched case control study

INTRODUCTION

Neural tube defects (NTDs) are severe birth defects caused by nutritional, genetic or environmental factors. Because NTDs continue to have a significant health and economic impact on children and community at large, it is crucial to investigate potential risk factors in order to develop novel approaches to NTDs prevention. Determinants for the development of NTDs differ by country, region as well as within the country. The objective of this study was to identify the determinants of NTDs among newborns delivered in three hospitals found in eastern Ethiopia.

METHODS

A hospital-based matched case-control study was conducted among 138 cases and 138 control women who delivered in three teaching hospitals in Eastern Ethiopia in 2021. Data were collected using a structured and pre-tested interviewer-administered questionnaire. Cases were mothers who delivered a neonate with any type of NTDs regardless of gestational age or fetal viability, whereas controls were mothers who delivered an apparently healthy newborn. Chi-square was used to assess the significant difference between the two groups. Conditional logistic regression model was used to generate adjusted odds ratio with its corresponding 95% confidence intervals and compare the two groups.

RESULTS

Anencephaly (51.4%) and spinal bifida (34.1%) were the most frequently observed NTDs. None of study participants took preconception folic acid supplementation. Being a non-formal mothers (AOR = 0.34, 95% CI: 0.12-0.92, P = 0.034), rural residence, (AOR = 3.4, 95% CI: 1.18-9.78, P = 0.023), history of spontaneous abortion (AOR = 2.95, 95% CI: 1.15-7.55, P = 0.023), having severe anemia (AOR = 3.4, 95% CI: 1.17-9.87, P = 0.024), history of fever or cold (AOR = 2.75; 95% CI: 1.05-7.15, P = 0.038), and an exposure to various agro-chemicals (AOR = 3.39, 95% CI: 1.11-10.3, P = 0.032) were independent determinants of NTDs.

CONCLUSION AND RECOMMENDATION

In this study, NTDs were associated to several determinant factors in the area, including residential area, history of spontaneous abortion, severe anemia, fever/cold, antibiotic use before or during early pregnancy, and exposure to agrochemicals. Addressing the identified determinants is critical in averting the incidence of NTDs in the study area. Moreover, more research is needed to investigate women's dietary practices as well as the practice of preconception folic acid supplementation for pregnant women in Ethiopia's current health care system.

Initiation and duration of folic acid supplementation in preventing congenital malformations

BACKGROUND

Folic acid (FA) supplementation is associated with a lower risk of the neural tube and heart defects and is recommended for women of childbearing age. Although there are detailed recommendations, differences in the initiation time and duration of FA supplementation remain poorly studied.

METHODS

A multicentre prospective study of 17,713 women was conducted. The incidence of congenital malformations in women taking a recommended dosage (e.g. 0.4 or 0.8 mg/day) of FA was compared with that in women without supplementation. The predicted probability of malformations by the initiation time and duration of FA use was estimated to determine optimal options.

RESULTS

Periconceptional FA supplementation was associated with a lower and insignificant risk of congenital malformations (1.59% vs. 2.37%; odds ratio [OR] 0.69; 95% confidence interval [CI]: 0.44-1.08), heart defects (3.8 vs. 8.0 per 1000 infants; OR, 0.47; 0.21-1.02), and neural tube defects (7.0 vs. 11.5 per 10,000 infants; OR, 0.64; 0.08-5.15). FA use after pregnancy provided greater protection against total malformations. Statistically significant associations were found in women who initiated FA supplementation in the first month of gestation (OR, 0.55; 95% CI: 0.33-0.91) and in those who supplemented for 1 to 2 months (OR, 0.59; 95% CI: 0.36-0.98). Similar results were found for heart defects. The optimal initiation time was 1.5 (optimal range: 1.1 to 1.9) months before pregnancy and a duration of 4.0 (3.7 to 4.4) months was reasonable to achieve the lowest risk of congenital malformations. Heart defect prevention required an earlier initiation (2.2 vs. 1.1 months before pregnancy) and a longer duration (4.7 vs. 3.7 months) than the prevention of other malformations.

CONCLUSIONS

The timely initiation of FA supplementation for gestation was associated with a decreased risk of congenital malformations, which was mainly attributed to its protection against heart defects. The initiation of FA supplementation 1.5 months before conception with a duration of 4 months is the preferred option for congenital malformation prevention.

TRIAL REGISTRATION

Chictr.org.cn identifier: ChiCTR-SOC-17010976.

Neural tube defects: a review of global prevalence, causes, and primary prevention

Neural tube defects (NTDs) are common birth defects and contribute to life-long disabilities, high medical care costs, and perinatal and child mortality. This review is a primer on prevalence, causes, and evidence-based prevention strategies for NTDs. The estimated average global prevalence of NTDs is two cases per 1000 births, amounting to approximately 214,000-322,000 affected pregnancies worldwide annually. Prevalence and associated adverse outcomes are disproportionately high in developing countries. NTDs have multiple risk factors including genetic and non-genetic (i.e., maternal nutritional status, pre-pregnancy diabetes, early pregnancy exposure to valproic acid (anti-epileptic medication), and a previous pregnancy affected by a NTD) factors. Maternal folate insufficiency before and during early pregnancy is the most common risk factor and is preventable. Folic acid (vitamin B9) is required for formation of the neural tube early in pregnancy, around 28 days after conception, when most women are unaware of their pregnancies. Current guidelines recommend that all women planning or capable of pregnancy take a daily supplement containing 400-800 μg of folic acid. Mandatory folic acid fortification of staple foods (e.g., wheat flour, maize flour, rice) is safe, economical, and the effective intervention for primary prevention of NTDs. Currently, about 60 countries are implementing mandatory folic acid fortification of staple foods, preventing just a quarter of all preventable NTD cases worldwide. There is an urgent need for active champions, including neurosurgeons and other healthcare providers, to generate political will and promote effective mandatory food fortification with folic acid, and reach equitable primary prevention of NTDs in all countries.

Fetal Repair of Neural Tube Defects

Myelomeningocele is the most common congenital neurologic defect, and the only nonlethal disease addressed by fetal surgery. A randomized control trial has established amelioration of the Arnold-Chiari II malformation, reduced ventriculoperitoneal shunt rate, and improvement in distal neurologic function in patients that receive in utero repair. Long-term follow-up of these school-age children demonstrates the persistence of these effects. The use of stem cells in fetal repair is being investigated to further improve distal motor function.

Folic Acid and the Prevention of Birth Defects: 30 Years of Opportunity and Controversies

For three decades, the US Public Health Service has recommended that all persons capable of becoming pregnant consume 400 μg/day of folic acid (FA) to prevent neural tube defects (NTDs). The neural tube forms by 28 days after conception. Fortification can be an effective NTD prevention strategy in populations with limited access to folic acid foods and/or supplements. This review describes the status of mandatory FA fortification among countries that fortify (n = 71) and the research describing the impact of those programs on NTD rates (up to 78% reduction), blood folate concentrations [red blood cell folate concentrations increased ∼1.47-fold (95% CI, 1.27, 1.70) following fortification], and other health outcomes. Across settings, high-quality studies such as those with randomized exposures (e.g., randomized controlled trials, Mendelian randomization studies) are needed to elucidate interactions of FA with vitamin B12 as well as expanded biomarker testing.

Eph and Ephrin Variants in Malaysian Neural Tube Defect Families

Neural tube defects (NTDs) are common birth defects with a complex genetic etiology. Mouse genetic models have indicated a number of candidate genes, of which functional mutations in some have been found in human NTDs, usually in a heterozygous state. This study focuses on Ephs-ephrins as candidate genes of interest owing to growing evidence of the role of this gene family during neural tube closure in mouse models. Eph-ephrin genes were analyzed in 31 Malaysian individuals comprising seven individuals with sporadic spina bifida, 13 parents, one twin-sibling and 10 unrelated controls. Whole exome sequencing analysis and bioinformatic analysis were performed to identify variants in 22 known Eph-ephrin genes. We reported that three out of seven spina bifida probands and three out of thirteen family members carried a variant in either EPHA2 (rs147977279), EPHB6 (rs780569137) or EFNB1 (rs772228172). Analysis of public databases shows that these variants are rare. In exome datasets of the probands and parents of the probands with Eph-ephrin variants, the genotypes of spina bifida-related genes were compared to investigate the probability of the gene–gene interaction in relation to environmental risk factors. We report the presence of Eph-ephrin gene variants that are prevalent in a small cohort of spina bifida patients in Malaysian families.

Production of human spinal-cord organoids recapitulating neural-tube morphogenesis

Human spinal-cord-like tissues induced from human pluripotent stem cells are typically insufficiently mature and do not mimic the morphological features of neurulation. Here, we report a three-dimensional culture system and protocol for the production of human spinal-cord-like organoids (hSCOs) recapitulating the neurulation-like tube-forming morphogenesis of the early spinal cord. The hSCOs exhibited neurulation-like tube-forming morphogenesis, cellular differentiation into the major types of spinal-cord neurons as well as glial cells, and mature synaptic functional activities, among other features of the development of the spinal cord. We used the hSCOs to screen for antiepileptic drugs that can cause neural-tube defects. hSCOs may also facilitate the study of the development of the human spinal cord and the modelling of diseases associated with neural-tube defects.

Prenatal uranium exposure and risk for fetal neural tube defects: A case-control study in women living in a rural area of northern China

The adverse effects of uranium exposure on human health are well-known; less is known, however, regarding its association with congenital malformations. We conducted a case-control study to examine the association between prenatal exposure to uranium and risk for fetal neural tube defects (NTDs) using the concentration of uranium in placental tissue as an exposure marker in 408 NTD cases and 593 healthy controls. Uranium concentration was quantified with an inductively coupled plasma mass spectrometer. The odds ratios of NTDs for uranium exposure levels, categorized into quartiles, were estimated using logistic regression. The median concentration of uranium in the NTD group (0.409 ng/g) was significantly higher than that in the control group (0.218 ng/g). The risk for NTDs increased 2.52-fold (95% CI, 1.85-3.45) for concentrations of uranium above the median value for all participants. After adjusting for confounders, the risk for NTDs increased 1.36-fold (95% CI, 1.25-6.17), 1.77-fold (95% CI, 1.09-2.85), and 3.60-fold (95% CI, 2.30-5.64) for the second, third, and fourth quartiles of uranium concentrations compared to the lowest quartile, respectively. Prenatal exposure to uranium is a risk factor for NTDs in this population. Prospective studies are needed to further validate this finding.

Fetal Occipital Encephalocele: A Case Report

Encephaloceles are considered neural tube defects, but their exact cause is unknown. The outcome is dismal, and essential management and counseling are needed for patients. Two-dimensional and three-dimensional sonography can be used to detect encephaloceles as early as 11 weeks, assist in treatment planning, and improve patient care. This case report presents an occipital encephalocele diagnosed by sonography and followed until delivery.

Parental metal exposures as potential risk factors for spina bifida in Bangladesh

BACKGROUND

Neural tube defects are a pressing public health concern despite advances in prevention from folic acid-based strategies. Numerous chemicals, in particular arsenic, have been associated with neural tube defects in animal models and could influence risk in humans.

OBJECTIVES

We investigated the relationship between parental exposure to arsenic and 17 metals and risk of neural tube defects (myelomeningocele and meningocele) in a case control study in Bangladesh.

METHODS

Exposure assessment included analysis of maternal and paternal toenail samples using inductively coupled plasma mass spectrometry (ICP-MS). A total of 278 participants (155 cases and 123 controls) with data collected from 2016 to 2020 were included in the analysis.

RESULTS

In the paternal models, a one-unit increase in the natural logarithm of paternal toenail arsenic was associated with a 74% (odds ratio: 1.74, 95% confidence interval: 1.26-2.42) greater odds of having a child with spina bifida, after adjusting for relevant covariates. Additionally, paternal exposure to aluminum, cobalt, chromium, iron, selenium, and vanadium was associated with increased odds of having a child with spina bifida in the adjusted models. In the maternal models, a one-unit increase in the natural logarithm of maternal toenail selenium and zinc levels was related to a 382% greater (odds ratio: 4.82, 95% confidence interval: 1.32-17.60) and 89% lower (odds ratio: 0.11, 95% confidence interval: 0.03-0.42) odds of having a child with spina bifida in the adjusted models, respectively. Results did not suggest an interaction between parental toenail metals and maternal serum folate.

DISCUSSION

Parental toenail levels of numerous metals were associated with increased risk of spina bifida in Bangladeshi infants. Paternal arsenic exposure was positively associated with neural tube defects in children and is of particular concern given the widespread arsenic poisoning of groundwater resources in Bangladesh and the lack of nutritional interventions aimed to mitigate paternal arsenic exposure. The findings add to the growing body of literature of the impact of metals, especially paternal environmental factors, on child health.

Periconceptional nonsteroidal anti-inflammatory drug use, folic acid intake, and the risk of spina bifida

BACKGROUND

Use of nonsteroidal anti-inflammatory drugs (NSAIDs) during pregnancy may increase risk for neural tube defects (NTDs), including spina bifida. Folic acid intake can prevent NTDs, but it is not known whether it modifies any risks associated with NSAID use.

OBJECTIVES

To assess the impact of periconceptional NSAID use on the risk of spina bifida overall and stratified by folic acid intake.

STUDY DESIGN

We analyzed 1998-2015 data from the Slone Epidemiology Center Birth Defects Study, a multi-site, case-control study. Mothers were interviewed to identify sociodemographic factors, behaviors, and exposures during pregnancy. Periconceptional NSAID use was defined as use of aspirin, ibuprofen, naproxen, or COX2 inhibitors within the month before or after the last menstrual period. Logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for NSAID use, adjusted for study center and race/ethnicity stratified by average daily folic acid intake above ("high FA") or below ("low FA") 400 mcg/day.

RESULTS

We compared mothers of 267 infants with spina bifida to mothers of 6,233 nonmalformed controls. Among control mothers, 20% used NSAIDS periconceptionally (16% ibuprofen, 4% aspirin, 3% naproxen, and <1% COX-2 inhibitors). For any NSAID use, the aORs among low FA and high FA women were 1.70 (95% CI [1.13, 2.57]) and 1.09 (95% CI [0.69, 1.71]), respectively.

CONCLUSIONS

We observed a small increase in the risk for spina bifida among infants born to women who used NSAIDs periconceptionally, but this risk was limited to those who had inadequate folic acid intake.

Associations between prenatal exposure to cadmium and lead with neural tube defect risks are modified by single-nucleotide polymorphisms of fetal MTHFR and SOD2: a case-control study

BACKGROUND

Prenatal exposure to heavy metals is implicated in the etiology of birth defects. We investigated whether concentrations of cadmium (Cd) and lead (Pb) in umbilical cord tissue are associated with risk for neural tube defects (NTDs) and whether selected genetic variants of the fetus modify their associations.

METHODS

This study included 166 cases of NTD fetuses/newborns and 166 newborns without congenital malformations. Umbilical cord tissue was collected at birth or elective pregnancy termination. Cd and Pb concentrations were assessed by inductively coupled plasma-mass spectrometry, and 20 single-nucleotide polymorphisms (SNPs) in 9 genes were genotyped. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the risk for NTDs in association with metal concentrations or genotype using logistic regression. Multiplicative-scale interactions between the metals and genotypes on NTD risk were assessed with logistic regression, and additive-scale interactions were estimated with a non-linear mixed effects model.

RESULTS

Higher concentrations of Cd were observed in the NTD group than in the control group, but no difference was found for Pb. Concentrations of Cd above the median level showed a risk effect, while the association between Pb and NTD risk was not significant in univariate analyses. The association of Cd was attenuated after adjusting for periconceptional folic acid supplementation. Fetuses with the AG and GG genotypes of rs4880 in SOD2 (superoxide dismutase 2) tended to have a lower risk, but fetuses with the CT and TT genotypes of rs1801133 in MTHFR (5,10-methylenetetrahydrofolatereductase) have a higher risk for NTDs when compared to their respective wild-type. rs4880 and Cd exhibited a multiplicative-scale interaction on NTD risk: the association between higher Cd and the risk for NTDs was increased by over fourfold in fetuses carrying the G allele [OR 4.43 (1.30-15.07)] compared to fetuses with the wild-type genotype. rs1801133 and Cd exposure showed an additive interaction, with a significant relative excess risk of interaction [RERI 0.64 (0.02-1.25)].

CONCLUSIONS

Prenatal exposure to Cd may be a risk factor for NTDs, and the risk effect may be enhanced in fetuses who carry the G allele of rs4880 in SOD2 and T allele of rs1801133 in MTHFR.

Prenatal exposure to organochlorine pesticides is associated with increased risk for neural tube defects

Neural tube defects (NTDs) are among the most common and disabling fetal congenital defects. Organochlorine pesticides (OCPs) are ubiquitous in the environment. In this study, 119 women who had NTD-affected pregnancies (cases) and 119 women who delivered healthy neonates (controls) were recruited in a rural area of Northern China. We used concentrations of OCPs in umbilical cord tissue as markers of prenatal exposure to investigate the association between in utero exposure to OCPs and NTD risk. Concentrations of 20 OCPs were quantified by gas chromatography-mass spectrometry, and 16 of the 20 OCPs were included in the analyses. Odds ratios and 95% confidence intervals (95% CIs) for the associations between levels of individual OCPs and NTD risk were estimated separately with logistic regression adjusting for potential confounders. The combined effects of exposure to the 16 OCPs as a mixture were analyzed with Bayesian kernel machine regression (BKMR). Logistic regression showed that the risk for NTDs increased 5.44-fold (95% CI, 2.21-13.41) for β-hexachlorocyclohexane, 2.51-fold (95% CI, 1.07-5.86) for endosulfan I, 3.78-fold (95% CI, 1.60-8.89) for endosulfan II, 3.42-fold (95% CI, 1.44-8.12) for ο,ρ'-dichlorodiphenyldichloroethane, and 2.89-fold (95% CI, 1.22-6.86) for ρ,ρ'-dichlorodiphenyltrichloroethane when the concentration of each of these OCPs was above its median (exposed) compared to below its median (non-exposed). Other OCPs were not associated with NTD risk in multivariate models. In BKMR, NTD risk increased almost linearly with concentrations of the 16 OCPs as a mixture, which suggests joint effects on NTD risk. Exposure to α-hexachlorocyclohexane, β-hexachlorocyclohexane, endosulfan II, ο,ρ'-dichlorodiphenyldichloroethane, and ρ,ρ'-dichlorodiphenyldichloroethane was associated with an increased risk for NTDs when levels of the remaining 15 OCPs were taken into account. Taken together, these findings show that prenatal exposure to OCPs is associated with increased risk for NTDs.

The Global Burden of Neural Tube Defects and Disparities in Neurosurgical Care

BACKGROUND

Despite the success of folic acid fortification programs, neural tube defects (NTDs) such as spina bifida, encephalocele, and anencephaly remain among the most substantial causes of childhood morbidity and mortality worldwide. Although these are complicated conditions that require an interdisciplinary approach to care, definitive treatment of survivable NTDs is often neurosurgical.

METHODS

Using Global Burden of Disease data, we examined the global burden of NTDs as related to a nation's wealth, health care quality, and access to neurosurgical care. We abstracted data for death by cause, years lived with disability (YLD), gross domestic product (GDP), United Nations geoscheme, Food Fortification Initiative participation, and Healthcare Access and Quality Index. We compared means using 1-way analysis of variance and proportions using Fisher exact tests, with statistical significance as α = 0.05.

RESULTS

Seventeen of 20 (85%) nations with the most deaths caused by NTDs (P < 0.0001) and 15/20 (75%) nations with the highest YLD (P < 0.0001) were in the lowest GDP quartile. Deaths and YLD were negatively correlated with increasing GDP and Healthcare Access and Quality Index (P < 0.0001). The nations with the highest disease burdens also had the fewest neurosurgeons per capita.

CONCLUSIONS

Despite the success of folic acid fortification programs, greater global public health efforts should be placed on improving access to neurosurgical care in low and middle-income nations through sustainable initiatives such as surgeon exchange programs and the establishment of neurosurgery residency training programs.

Perspectives on urological care in spina bifida patients

Spina bifida (SB) is a neurogenetic disorder with a complex etiology that involves genetic and environmental factors. SB can occur in two major forms of open SB or SB aperta and closed SB or SB occulta. Myelomeningocele (MMC), the most common neural tube defects (NTDs), occurs in approximately 1 in 1,000 births. Considering non-genetic factors, diminished folate status is the best-known factor influencing NTD risk. The methylenetetrahydrofolate reductase (MTHFR) gene has been implicated as a risk factor for NTDs. The primary disorder in the pathogenesis of MMC is failed neural tube closure in the embryonic spinal region. The clinical manifestation of SB depends on clinical type and severity. SB can be detected in the second trimester using ultrasound which will reveal specific cranial signs. The management of MMC traditionally involves surgery within 48 h of birth. Prenatal repair of MMC is recommended for fetuses who meet maternal and fetal Management of Myelomeningocele Study (MOMS) specified criteria. Urological manifestations of SB include urinary incontinence, urolithiasis, sexual dysfunction, renal dysfunction, and urinary tract infection. Renal failure is among the most severe complications of SB. The most important role of the urologist is the management of neurogenic bladder. Medical management with clean intermittent catheterization and anticholinergic treatment is generally considered the gold standard of therapy. However, when this therapy fails surgical reconstruction become the only remaining option. This review will summarize the pathogenesis, risk factors, genetic contribution, diagnostic test, and management of SB. Lastly, the urologic outcomes and therapies are reviewed.

Projected impact of mandatory food fortification with folic acid on neurosurgical capacity needed for treating spina bifida in Ethiopia

Spina bifida, also known as meningomyelocele, is a major birth defect mostly associated with folate deficiency in the mother early in pregnancy. The prevalence of spina bifida is disproportionately high in Ethiopia compared to the global average; about 10,500 liveborn are affected annually. Many affected infants do not receive timely repair surgery. There are a high number of stillbirths, and neonatal, infant, and under‐five deaths. Mandatory fortification of staple foods such as wheat and maize flour with folic acid, a B vitamin, is an effective primary prevention strategy for spina bifida. Survival in those with spina bifida increases if neurosurgical intervention is available soon after birth, along with continuous surgical and clinical aftercare throughout the lifespan. Currently, Ethiopia does not have mandatory food fortification for primary prevention or adequate neurosurgical capacity to meet the need to prevent adverse outcomes associated with spina bifida. We present in this paper two concurrent and complementary policy and practice solutions occurring in Ethiopia through global partnerships: (1) capacity‐building of neurosurgery care through training programs; and (2) promoting national mandatory folic acid fortification of staples for primary prevention of spina bifida. These two policy and practice interventions ensure all affected infants can receive timely pediatric neurosurgery and sustained surgical aftercare through required neurosurgeon availability, and ensure primary prevention of spina bifida. Primary prevention of spina bifida frees up significant neurosurgical capacity in resource‐poor settings that can then be directed to other critical neurosurgical needs thus lowering child mortality and morbidity.

Lower rates of neural tube defects in Israel following folic acid supplementation policy

Neural tube defects (NTDs) are common and disabling congenital malformations that remain a public health challenge despite prevention efforts. In 2000, The Israeli Ministry of Health published recommendations on daily folic acid (FA) supplementation for women of reproductive age and established a national NTD registry. This study aims to evaluate the long-term impact of the FA supplementation policy on NTD rates in Israel and the need for further intervention. In this descriptive report, we present the rate of NTD-affected pregnancies recorded in the registry between 2000 and 2012, their subtype (anencephaly, spina bifida or other), outcome (live birth, stillbirth or pregnancy termination), ethnic group (Jewish, Bedouin and non-Bedouin Muslim) and years of maternal education. The final analysis included 2374 NTD cases reported between 2000 and 2012, compared with 1,668,073 live births. During this period NTD rates decreased from 20.3 to 11.2 cases per 10,000 live births, a 45% reduction. Reductions were seen in rates of spina bifida, anencephaly and encephalocele. NTD rates decreased in all pregnancy outcomes and in all ethnic groups, though rates among Bedouins remain high. Women with higher levels of education tended to have lower NTD rates, and were more prone to choose termination of an affected pregnancy. Following the institution of FA supplementation in Israel, a substantial reduction was seen in NTD rates. Nonetheless, Israeli NTD rates remain higher than in other developed countries. FA interventions should continue to be vigorously implemented, especially in vulnerable populations. The global success of mandatory fortification of grain strongly advocates its consideration in Israel.

Burden of rare deleterious variants in WNT signaling genes among 511 myelomeningocele patients

Genes in the noncanonical WNT signaling pathway controlling planar cell polarity have been linked to the neural tube defect myelomeningocele. We hypothesized that some genes in the WNT signaling network have a higher mutational burden in myelomeningocele subjects than in reference subjects in gnomAD. Exome sequencing data from 511 myelomeningocele subjects was obtained in-house and data from 29,940 ethnically matched subjects was provided by version 2 of the publicly available Genome Aggregation Database. To compare mutational burden, we collapsed rare deleterious variants across each of 523 human WNT signaling genes in case and reference populations. Ten WNT signaling genes were disrupted with a higher mutational burden among Mexican American myelomeningocele subjects compared to reference subjects (Fishers exact test, P ≤ 0.05) and seven different genes were disrupted among individuals of European ancestry compared to reference subjects. Gene ontology enrichment analyses indicate that genes disrupted only in the Mexican American population play a role in planar cell polarity whereas genes identified in both populations are important for the regulation of canonical WNT signaling. In summary, evidence for WNT signaling genes that may contribute to myelomeningocele in humans is presented and discussed.

Essential trace elements in umbilical cord tissue and risk for neural tube defects

Deficient or excessive quantities of essential trace elements (ETEs)¹ in the fetal environment can compromise developmental processes. We investigated whether concentrations of zinc (Zn), manganese (Mn), selenium (Se), cobalt (Co), molybdenum (Mo), and nickel (Ni) in umbilical cord tissue are associated with risk for neural tube defects (NTDs). Umbilical cord tissues from 166 cases of NTD cases and 166 matched controls were collected and element concentrations were measured using inductively coupled plasma-mass spectrometry. Associations between ETE concentrations and the risk for NTDs were estimated using multivariate logistic regression while adjusting for potential confounders. Bayesian kernel machine regression (BKMR) was used to examine the joint effects of these ETEs. We found that median concentrations of Ni were higher but those of Mo and Co were lower in the NTD group than in the control group. Co was the only element that was associated with NTD risk after adjusting for confounders (OR 0.31, 95 % CI 0.12-0.79 for the second and OR 0.37, 95 % CI 0.15-0.91 for the top tertile relative to the lowest tertile). The association between Co and NTD risk was confirmed with the BKMR model. In addition, a joint effect of the six ETE mixture on NTD risk was observed: the risk decreased with the levels of the mixture from 25th percentile through 75th percentile. In conclusion, higher levels of Co were associated with lower risk for NTDs, and NTD risk decreased with the levels of the six ETEs as a co-exposure mixture, suggesting a protective effect.

Prenatal Hypoxia and Placental Oxidative Stress: Insights from Animal Models to Clinical Evidences

Hypoxia is a common form of intrauterine stress characterized by exposure to low oxygen concentrations. Gestational hypoxia is associated with the generation of reactive oxygen species. Increase in oxidative stress is responsible for damage to proteins, lipids and DNA with consequent impairment of normal cellular functions. The purpose of this review is to propose a summary of preclinical and clinical evidences designed to outline the correlation between fetal hypoxia and oxidative stress. The results of the studies described show that increases of oxidative stress in the placenta is responsible for changes in fetal development. Specifically, oxidative stress plays a key role in vascular, cardiac and neurological disease and reproductive function dysfunctions. Moreover, the different finding suggests that the prenatal hypoxia-induced oxidative stress is associated with pregnancy complications, responsible for changes in fetal programming. In this way, fetal hypoxia predisposes the offspring to congenital anomalies and chronic diseases in future life. Several antioxidant agents, such as melatonin, erythropoietin, vitamin C, resveratrol and hydrogen, shown potential protective effects in prenatal hypoxia. However, future investigations will be needed to allow the implementation of these antioxidants in clinical practice for the promotion of health in early intrauterine life, in fetuses and children.

The etiopathogenic and morphological spectrum of anencephaly: a comprehensive review of literature

Anencephaly is a severe malformation of the central nervous system (CNS), being one of the most common types of neural tube defects. It is defined as total or partial absence of the calvarium, with absence of the brain. Anencephaly has an incidence of 1 to 5 in every 1000 births, and the mortality rate is 100% during intrauterine life or within hours or days after birth. The etiology of anencephaly remains unclear, but various maternal-related environmental and genetic risk factors have been reported, which include diabetes, obesity, exposure to different drugs or toxins, genetic polymorphisms and mutations, as well as positive family history for neural tube defects. One of the most important nutritional factors in the development of anencephaly is folate deficiency. Methylenetetrahydrofolate reductase (MTHFR) gene codes the enzyme involved in the intracellular metabolism of folic acid; the 677C-T polymorphism of this gene causes the thermolability of the enzyme and decreased enzymatic activity, which is also dependent of folate plasmatic level. Etiopathogenesis of anencephaly includes several mutations in various other genes, such as: platelet-derived growth factor receptor alpha (PDGFRA), cadherin epidermal growth factor (EGF) laminin G (LAG) seven-pass G-type receptor 1 (CELSR1), Vang-like 1 (VANGL1) and Vang-like 2 (VANGL2), the last two being involved in the process of neurulation. Screening tests include maternal serum alpha-fetoprotein level and ultrasound (US) examination. During the first trimester US screening, anencephaly is now detected in all cases, but in order to decrease the complication rate of pregnancy termination, the diagnosis should be established as soon as possible, during the pregnancy confirmation US. We conclude that given that anencephaly is a severe malformation of the CNS, morphological characterization could improve the screening by US that is mandatory in the first trimester in order to plan the best, safe and early management.

Association between maternal pregestational diabetes mellitus and spina bifida: A population-based case-control study, Finland, 2000-2014

BACKGROUND

Maternal pregestational diabetes mellitus (PGDM) is a known risk factor for neural tube defects. We examined the association between maternal PGDM and spina bifida in the offspring using PGDM status from medical records in Finland.

METHODS

We conducted a nationally representative, multiregistry, population-based case-control study in Finland. Cases were included if they were live or stillborn infants and diagnosed with spina bifida and delivered between years 2000 and 2014 in Finland. Controls were Finnish infants without spina bifida or other major structural birth defects and delivered during the same time period as cases. Clinical and demographic data were obtained by linking multiple national health registers and census. Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CI) for PGDM were estimated using logistic regression analysis. Interaction by maternal obesity was examined.

RESULTS

Our study included 181 spina bifida cases (61% isolated) and 876,672 controls. Overall, 2.2% percent of all case, and 0.5% of control mothers, had PGDM during pregnancy. Maternal PGDM was significantly associated with an increased odds of spina bifida (adjusted OR 4.35; 95% CI 1.37, 13.82). A similar association was found in our subanalysis on isolated spina bifida cases (adjusted OR 4.41; 95% CI 1.07, 18.24). There was no significant interaction by maternal obesity.

CONCLUSIONS

Maternal PGDM was positively associated with spina bifida in Finland, and maternal obesity did not modify this effect. We lacked information on maternal PGDM for electively terminated and spontaneously aborted cases; results should be interpreted with caution.

Maternal, paternal, and neonatal risk factors for neural tube defects: A systematic review and meta-analysis

OBJECTIVE

Neural tube defects [NTDs] are severe congenital anomalies. The etiology of NTDs is not fully known, and studies on the potential risk factors of NTDs present inconsistent results. Thus, we conducted a systematic review and meta-analysis to investigate the maternal, paternal, and neonatal risk factors for NTDs.

STUDY DESIGN

We systematically reviewed relative original studies published through October 6, 2018 available in Pubmed, Embase and the Cochrane Library without restrictions for language. The selected studies measured maternal, paternal, and neonatal risk factors and examined their associations with NTDs. A meta-analysis, including subgroup analysis and sensitivity analysis, was conducted to estimate the pooled effect measures. Two reviewers independently extracted data using a predesigned data collection form.

RESULTS

Forty-five studies were eligible for inclusion in the meta-analysis, and twelve potential risk factors were analyzed. The factors that were associated with NTDs risk included stressful life events [odds ratio [OR],1.61; 95% confidence interval [CI], 1.24-2.08; p < 0.001; I2 = 59.2%], low maternal education level [OR, 1.42; 95% CI, 1.19-1.70; p < 0.001; I2 = 47.7%], pregestational diabetes [OR, 2.24; 95% CI, 1.21-4.12; p < 0.010; I2 = 56.3%], low paternal age [OR, 1.41; 95% CI, 1.10-1.81; p = 0.007; I2 = 0.0%], low birth weight [OR, 5.53; 95% CI, 1.95-15.70; p = 0.001; I2 = 98.5%], and neonatal female gender [OR, 1.54; 95% CI, 1.10-2.14; p = 0.012; I2 = 67.8%].

CONCLUSION

Stressful life events, pregestational diabetes, low birth weight, and neonatal female gender are risk factors associated with NTDs. Low maternal education level and low paternal age are factors that are moderately associated with NTDs. Further cohort studies are required to verify the factors associated with NTDs and control the risk of this severe birth defect.

Periconceptional folic acid and risk for neural tube defects among higher risk pregnancies

BACKGROUND

Women with a previous neural tube defect (NTD)-affected pregnancy are recommended to consume 4,000 μg daily folic acid (FA) for prevention (10 times the general-population recommendation). Protection from doses between 400 and 4,000 μg for this and other higher risk groups is unclear.

METHODS

In the case-control Slone Birth Defects Study (1988-2015), we examined the associations between periconceptional FA doses and NTDs among four higher risk groups: NTD family history, periconceptional antiepileptic drug exposure (AED), pregestational diabetes, and prepregnancy obesity. Mothers completed standardized interviews about pregnancy events and exposures. FA categorizations were based on (a) supplements only and (b) supplements and diet ("total folate"). We estimated odds ratios (ORs) and 95% confidence intervals (CIs) (adjusted for age and study center) using logistic regression.

RESULTS

Cases and controls included: 45 and 119 with family history, 25 and 108 with AED exposure, 12 and 63 with pregestational diabetes, 111 and 1,243 with obesity. Daily FA supplementation was associated with lower NTD risk compared to no supplementation (adjusted ORs were 0.33 [95% CI 0.13, 0.76] for family history, 0.31 [0.09, 0.95] for AED exposure, 0.25 [0.04, 1.05] for pregestational diabetes, 0.65 [0.40, 1.04] for obesity). Though estimates were imprecise, as total folate increased stronger point estimates were observed, notably among family history. No mothers with a prior NTD-affected pregnancy supplemented with 4,000 μg.

CONCLUSIONS

Our findings reinforce that all women of childbearing potential should consume at least 400 μg FA/day to protect against NTDs. Higher risk groups may benefit from higher doses.

Decreased global DNA hydroxymethylation in neural tube defects: Association with polycyclic aromatic hydrocarbons

5-Hydroxymethylcytosine (5hmC), a distinct epigenetic marker that plays a role in DNA active demethylation, has been reported to be important for embryonic development and may respond to environmental exposure. No studies have evaluated the association between DNA hydroxymethylation and the risk for fetal neural tube defects (NTDs), with consideration of prenatal exposure to polycyclic aromatic hydrocarbons (PAHs), a risk factor for NTDs. We measured the global levels of 5hmC% in neural tissue from 92 terminated NTD cases and 33 terminated non-malformed fetuses. A lower level of 5hmC% was found in the NTD cases (median [interquartile range]: 0.25 [0.12-0.39]) compared to the controls (0.45 [0.19-1.00]). After adjusting for periconceptional folate supplementation, risk for NTDs increased with decreasing tertiles of 5hmC% (odds ratio: 7.89, 95% confidence interval: 2.32, 26.86, for the lowest tertile relative to the top tertile; p_{for trend} = 0.002). Linear regression revealed that concentrations of high-molecular-weight PAHs (H_PAHs) in fetal liver tissue were negatively associated with log2-transformed 5hmC%. Superoxide dismutase activity and 5hmC% were positively correlated in fetal neural tissue (r_s = 0.64; p < 0.05). A mouse whole-embryo culture model was used for further validation. Decreased levels of 5hmC% and increased levels of reactive oxygen species were found in mouse embryos treated with BaP, a well-studied PAH. Taken together, levels of 5hmC% in fetal neural tissue were inversely associated with the risk for NTDs, and this association may be related to oxidative stress induced by exposure to PAHs.

A case-control analysis of maternal diet and risk of neural tube defects in Bangladesh

OBJECTIVES

Mothers need a nutrient-rich diet for healthy neural tube development. Neural tube defect risk can be reduced through fortifying grain products with folic acid and taking folic acid supplements. Fortification is not required in Bangladesh. Maternal supplement use rates are low, similar to other countries. This study evaluates maternal dietary intake during pregnancy to identify possible interventions.

METHODS

A food frequency questionnaire (FFQ) assessed maternal diet. The primary aim compared dietary intake (calories, fat, carbohydrate, protein, fiber, vitamins, and minerals) between mothers of infants with myelomeningocele (cases) and mothers of controls. Secondary aims included (i) comparing foods consumed and (ii) evaluating if rice intake correlated with arsenic exposure. Paired t-tests, Wilcoxon signed rank tests, McNemar's chi-squared test, and linear regression were used.

RESULTS

This study included 110 matched mother-infant pairs (55 cases/55 controls). Mothers of cases and mothers of controls had similar caloric intake [median 2406 kcal/day vs. 2196 kcal/day (p = 0.071)]. Mothers in both groups consumed less than half the daily recommended 600 μg of folate. Diets were potentially deficient in vitamins A, D, E, potassium, sodium, and iron. Steamed rice was the primary food consumed for both groups, and this rice intake was not associated with toenail arsenic.

CONCLUSIONS

Dietary interventions should increase folate, vitamins A, D, E, potassium, sodium, and iron intake in Bangladeshi mothers. Folic acid fortification of grain products maybe the only viable strategy to achieve adequate folate intake for mothers. Given the central role of rice to the Bangladeshi diet, fortifying rice may be a viable option.

TRIM4 is associated with neural tube defects based on genome-wide DNA methylation analysis

BACKGROUND

Neural tube defects (NTDs) are complex abnormalities associated with gene-environment interactions. The underlying cause has not been determined.

METHODS

Spinal cord tissues from cases with NTDs and healthy controls were collected. Methylation patterns between cases and normal individuals were compared using 450K Infinium Methylation BeadChip Illumina. DNA methylation analysis by pyrosequencing (PyroMark Q96) and mRNA and protein expression were analyzed using real-time quantitative PCR and Western blotting, respectively. Next-generation and Sanger sequencing were used to determine genetic variants in the target genes.

RESULTS

Spinal cord tissues from cases with NTDs had more hypomethylated than hypermethylated genes. Further evaluation showed that the exon 1 region of TRIM4 was hypomethylated, and TRIM4 mRNA and protein levels were significantly increased in NTDs compared to controls. A rare missense variant (rs76665876) in TRIM4 was found in 3 of the 14 NTD cases but was not related to TRIM4 expression. TRIM4 mRNA levels were significantly increased in cases with hypomethylation and without the rs76665876 variant.

CONCLUSION

These findings suggest that spinal cord tissues in cases with NTDs had a different genome-wide methylation pattern compared to controls. Abnormal methylation patterns in TRIM4 in immunity pathways might be involved in NTD pathogenesis. Genetic variants in TRIM4 genes only slightly contribute to the etiology of human NTDs.

The Role of Oxidative Stress in the Pathomechanism of Congenital Malformations

Congenital anomalies are significant causes of mortality and morbidity in infancy and childhood. Embryogenesis requires specific signaling pathways to regulate cell proliferation and differentiation. These signaling pathways are sensitive to endogenous and exogenous agents able to produce several structural changes of the developing fetus. Oxidative stress, due to an imbalance between the production of reactive oxygen species and antioxidant defenses, disrupts signaling pathways with a causative role in birth defects. This review provides a basis for understanding the role of oxidative stress in the pathomechanism of congenital malformations, discussing the mechanisms related to some congenital malformations. New insights in the knowledge of pathomechanism of oxidative stress-related congenital malformations, according to experimental and human studies, represent the basis of possible clinical applications in screening, prevention, and therapies.

Understanding how the concentration of neighborhood advantage and disadvantage affects spina bifida risk among births to non-Hispanic white and Hispanic women, Texas, 1999-2014

BACKGROUND

This is the first study to utilize the index of concentration at the extremes (ICE) to examine risk factors for spina bifida in Texas. The ICE is a useful measure for providing the degree to which residents in a certain area are concentrated into groups at the extremes of disadvantage and privilege. We introduce two novel ICE measures (language and nativity), and three existing ICE measures (race/ethnicity, income, and education), which we applied specifically to Texas residents.

METHODS

We used multivariable mixed-model Poisson regression analyses to estimate spina bifida birth prevalence and prevalence ratios among singleton live births in Texas, 1999-2014, for each of our ICE measures. Maternal census tract at delivery was included in the models as a random effect. Analyses were stratified by maternal race/ethnicity (Hispanics and non-Hispanic whites). Live births served as denominators for each category.

RESULTS

Among non-Hispanic white women, those in the most disadvantaged versus the advantaged census tract quintile had adjusted relative risk between 1.6 and 8.5 for having a baby affected by spina bifida. However, Hispanic women in the most disadvantaged versus advantaged census tract quintile for four ICE measures had a 33% to 87% lower risk of having an affected pregnancy.

CONCLUSIONS

Findings suggest spina bifida risk is associated with neighborhood disadvantage or advantage, and that relationship seems to vary by race-ethnicity. The varied associations between ICE measures and spina bifida by race/ethnicity highlights the importance of using targeted interventions in the prevention of spina bifida.

Proportion of Orofacial Clefts Attributable to Recognized Risk Factors

OBJECTIVE

Estimate the population attributable fraction (PAF) for a set of recognized risk factors for orofacial clefts.

DESIGN

We used data from the National Birth Defects Prevention Study. For recognized risk factors for which data were available, we estimated crude population attributable fractions (cPAFs) to account for potential confounding, average-adjusted population attributable fractions (aaPAFs). We assessed 11 modifiable and 3 nonmodifiable parental/maternal risk factors. The aaPAF for individual risk factors and the total aaPAF for the set of risk factors were calculated using a method described by Eide and Geffler.

SETTING

Population-based case-control study in 10 US states.

PARTICIPANTS

Two thousand seven hundred seventy-nine cases with isolated cleft lip with or without cleft palate (CL±P), 1310 cases with isolated cleft palate (CP), and 11 692 controls with estimated dates of delivery between October 1, 1997, and December 31, 2011.

MAIN OUTCOME MEASURES

Crude population attributable fraction and aaPAF.

RESULTS

The proportion of CL±P and CP cases attributable to the full set of examined risk factors was 50% and 43%, respectively. The modifiable factor with the largest aaPAF was smoking during the month before pregnancy or the first month of pregnancy (4.0% for CL±P and 3.4% for CP). Among nonmodifiable factors, the factor with the largest aaPAF for CL±P was male sex (27%) and for CP it was female sex (16%).

CONCLUSIONS

Our results may inform research and prevention efforts. A large proportion of orofacial cleft risk is attributable to nonmodifiable factors; it is important to better understand the mechanisms involved for these factors.

Oxidative Stress and Apoptosis in Benzo[a]pyrene-Induced Neural Tube Defects

Neural tube defects (NTDs) are among the most common and severe congenital malformations and result from incomplete closure of the neural tube during early development. Maternal exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested to be a risk factor for NTDs and previous studies imply that the mechanism underlying the association between PAH exposure and NTDs may involve oxidative stress and apoptosis. The objectives of this study were to investigate whether there is a direct effect of maternal benzo[α] pyrene (BaP) exposure on the closure of the neural tube in mice, and to examine the underlying mechanisms by combining animal experiments and human subject studies. We found that intraperitoneal injection of BaP from embryonic day 7 at a dose of 250 mg kg^-1 induced NTDs (13.3% frequency) in ICR mice. BaP exposure significantly increased expression of genes associated with oxidative stress, Cyp1a1, Sod1 and Sod2, while repressing Gpx1. Elevated apoptosis and higher protein expression of cleaved caspase-3 in the neuroepithelium of treated embryos were observed. Pre-treatment with vitamin E, added to food, significantly protected against BaP-induced NTDs (1.4% frequency) (P < 0.05). Vitamin E also partly normalized oxidative stress related gene expression and excess apoptosis in BaP-treated embryos. Examination of human neural tissues revealed that increased levels of protein carbonyl and apoptosis were related with maternal exposure to PAHs and the risk of NTDs. Collectively, these results suggest that BaP exposure could induce NTDs and that this may involve increased oxidative stress and apoptosis, while vitamin E may have a protective effect.

Mood-Stabilizing Anticonvulsants, Spina Bifida, and Folate Supplementation: Commentary

PURPOSE/BACKGROUND

High risks of neural tube defects and other teratogenic effects are associated with exposure in early pregnancy to some anticonvulsants, including in women with bipolar disorder.

METHODS/PROCEDURES

Based on a semistructured review of recent literature, we summarized findings pertaining to this topic.

FINDINGS/RESULTS

Valproate and carbamazepine are commonly used empirically (off-label) for putative long-term mood-stabilizing effects. Both anticonvulsants have high risks of teratogenic effects during pregnancy. Risks of neural tube defects (especially spina bifida) and other major malformations are especially great with valproate and can arise even before pregnancy is diagnosed. Standard supplementation of folic acid during pregnancy can reduce risk of spontaneous spina bifida, but not that associated with valproate or carbamazepine. In contrast, lamotrigine has regulatory approval for long-term use in bipolar disorder and appears not to have teratogenic effects in humans.

IMPLICATIONS/CONCLUSIONS

Lack of protective effects against anticonvulsant-associated neural tube defects by folic acid supplements in anticipation of and during pregnancy is not widely recognized. This limitation and high risks of neural tube and other major teratogenic effects, especially of valproate, indicate the need for great caution in the use of valproate and carbamazepine to treat bipolar disorder in women of child-bearing age.

Mutations in folate transporter genes and risk for human myelomeningocele

The molecular mechanisms linking folate deficiency and neural tube defect (NTD) risk in offspring remain unclear. Folate transporters (SLC19A1, SLC46A1, SLC25A32, and FOLH1) and folate receptors (FOLR1, FOLR2, and FOLR3) are suggested to play essential roles in transporting folate from maternal intestinal lumen to the developing embryo. Loss of function variants in these genes may affect folate availability and contribute to NTD risk. This study examines whether variants within the folate transporter and receptor genes are associated with an increased risk for myelomeningocele (MM). Exons and their flanking intron sequences of 348 MM subjects were sequenced using the Sanger sequencing method and/or next generation sequencing to identify variants. Frequencies of alleles of single nucleotide polymorphisms (SNPs) in MM subjects were compared to those from ethnically matched reference populations to evaluate alleles' associated risk for MM. We identified eight novel variants in SLC19A1 and twelve novel variants in FOLR1, FOLR2, and FOLR3. Pathogenic variants include c.1265delG in SLC19A1 resulting in an early stop codon, four large insertion deletion variants in FOLR3, and a stop_gain variant in FOLR3. No new variants were identified in SLC46A1, SLC25A32, or FOLH1. In SLC19A1, c.80A>G (rs1051266) was not associated with our MM cohort; we did observe a variant allele G frequency of 61.7%, higher than previously reported in other NTD populations. In conclusion, we discovered novel loss of function variants in genes involved in folate transport in MM subjects. Our results support the growing evidence of associations between genes involved in folate transport and susceptibility to NTDs.

Pre-pregnancy Obesity as a Modifier of Gestational Diabetes and Birth Defects Associations: A Systematic Review

Objective Inconsistent findings of associations between gestational diabetes mellitus (GDM) and birth defects suggest unaccounted confounders may underlie the actual basis for such associations. We conducted a systematic review to assess observed associations between GDM and birth defects and the extent to which these could be explained by pre-pregnancy obesity. Methods Using a combination of search terms for GDM and birth defects, we searched PubMed, Scopus, CINAHL, and ClinicalTrials.gov for human-based studies published through September 2013. Studies were eligible for inclusion if they included information on maternal diabetes status, method of diagnosis of GDM, and assessment of birth defects. Twenty-four of 768 potential articles were included. We collected information on study design, location and period, method of determination of diabetes status, types of birth defects, and measures of association reported. Results There was no evidence for consistent association of GDM with birth defects, with the exception of a weak association between GDM and congenital heart defects. When stratified by maternal pre-pregnancy BMI, an association between GDM and congenital heart defects and between GDM and neural tube defects was evident only in women with both GDM and pre-pregnancy obesity. Conclusions for Practice Our findings suggest reported associations between GDM and birth defects may be due, in part, to undiagnosed metabolic disorders associated with obesity, such as pregestational diabetes mellitus, rather than GDM. These findings highlight the need for increased efforts for pre-pregnancy screening for undiagnosed diabetes and awareness of the importance of weight management among women of childbearing age with obesity.

Maternal occupation and the risk of neural tube defects in offspring

We evaluated the association between maternal occupation and the risk of neural tube defects (NTDs) in offspring. Data for 491 nonsyndromic cases were obtained from the Texas Birth Defects Registry for deliveries between 1999 and 2009. We randomly selected 2,291 controls among all live births in Texas during this time. Maternal occupations were classified using automated software and manual assignment. Multivariable logistic regression analyses were used to examine the relationship between maternal occupation and risk for any NTD, adjusting for maternal race/ethnicity, any diabetes, and maternal body mass index. These analyses were repeated for spina bifida specifically. Some maternal occupations, particularly those related to business/finance, health care practice, and cleaning/maintenance, were significantly associated with increased risk of spina bifida and/or any NTD. Further research is needed to identify the specific occupational exposures related to NTD risk.

The impact of folic acid supplementation on gestational and long term health: Critical temporal windows, benefits and risks

Highlights

Associations between FA supplementation in pregnancy and effects on offspring's NTDs, allergy/respiratory problems, cancer and behaviour problems as been studied.There is growing concern about the effects of excessive FA supplementation, whether in terms of doses or times of exposure.FA supplementation in the periconceptional period is protective against NTDs while in later periods it could be deleterious.A daily dose of 0.4 mg FA in the periconceptional period seems to be effective and safe.

Abstract

Maternal folic acid (FA) supplementation is one of the most popular nutritional interventions during pregnancy for its protective effect against neural tube defects (NTDs).The purposes of this review are: (a) to gather the current evidence regarding supplementation of maternal diet with FA and (b) to problematize the available literature in terms of dosages, critical temporal windows, and its potential benefits and risks.The expression (pregnancy OR fetus OR offspring OR mother) AND ("folic acid" AND supplementation) was searched on PubMed database, filtering for articles published from 2005 to 2014. Publications referring to FA supplementation during the periconceptional period or pregnancy in which there was a conclusion about the effects of isolated FA supplementation on pregnant woman, pregnancy or offspring were included. Of the initial 1182 papers, 109 fulfilled the inclusion criteria.The majority of the publications reported FA supplementation outcomes on offspring's health, with emphasis in NTDs, allergy/respiratory problems, cancer and behaviour problems. Some inconsistency is observed on the impact of FA supplementation on different outcomes, except for NTDs. It is also visible an increased concern about the impact of excessive supplementation, either in terms of doses or exposure's duration.In conclusion, there is a growing interest in FA supplementation issues. The protective effect of FA supplementation over NTDs has been confirmed, being the periconceptional period a critical window, and it is frequently suggested that allergy/respiratory outcomes arise from (excessive) FA supplementation particularly later in pregnancy. Further research on critical doses and time of exposure should be conducted.

Clinical and molecular genetic characterization of two siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter

Partial trisomy 2p syndrome is occasionally associated with neural tube defects (NTDs), such as anencephaly, encephalocele, and spina bifida, in addition to common features of intellectual disability, developmental delay, and characteristic facial appearance. The 2p24 region has been reported to be associated with NTDs. Here, we report the cases of 2 siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter caused by the paternal translocation t(2;5)(p24.3;p14.3). Of the two siblings, the elder sister had spina bifida. We determined the nucleotide sequences of the chromosomal breakpoints and found that the sizes of trisomy 2p and monosomy 5p segments were 18.77 and 17.89 Mb, respectively. NTDs were present in four of seven previously reported patients with trisomy 2p and monosomy 5p as well as in one of the two patients examined in the present study. Although the monosomy 5p of the nine patients were similar in size, the two patients reported here had the smallest size of trisomy 2p. When the clinical features of the nine patients were compared to the present two patients, the elder sister had postaxial polydactyly of the left foot in addition to the characteristic facial appearance and spina bifida, indicating that these features were associated with trisomy 2p24.3-pter. To our knowledge, this is the first study on spina bifida to determine the nucleotide sequences of breakpoints for trisomy 2p24.3-pter and monosomy 5p14.3-pter. Increased gene dosages of dosage-sensitive genes or genes at the trisomy segment (2p24.3) of the presented patients could be associated with NTDs of patients with trisomy 2p.

Fetal DNA hypermethylation in tight junction pathway is associated with neural tube defects: A genome-wide DNA methylation analysis

Neural tube defects (NTDs) are a spectrum of severe congenital malformations of fusion failure of the neural tube during early embryogenesis. Evidence on aberrant DNA methylation in NTD development remains scarce, especially when exposure to environmental pollutant is taken into consideration. DNA methylation profiling was quantified using the Infinium HumanMethylation450 array in neural tissues from 10 NTD cases and 8 non-malformed controls (stage 1). Subsequent validation was performed using a Sequenom MassARRAY system in neural tissues from 20 NTD cases and 20 non-malformed controls (stage 2). Correlation analysis of differentially methylated CpG sites in fetal neural tissues and polycyclic aromatic hydrocarbons concentrations in fetal neural tissues and maternal serum was conducted. Differentially methylated CpG sites of neural tissues were further validated in fetal mice with NTDs induced by benzo(a)pyrene given to pregnant mice. Differentially hypermethylated CpG sites in neural tissues from 17 genes and 6 pathways were identified in stage 1. Subsequently, differentially hypermethylated CpG sites in neural tissues from 6 genes (BDKRB2, CTNNA1, CYFIP2, MMP7, MYH2, and TIAM2) were confirmed in stage 2. Correlation analysis showed that methylated CpG sites in CTNNA1 and MYH2 from NTD cases were positively correlated to polycyclic aromatic hydrocarbon level in fetal neural tissues and maternal serum. The correlation was confirmed in NTD-affected fetal mice that were exposed to benzo(a)pyrene in utero. In conclusion, hypermethylation of the CTNNA1 and MYH2 genes in tight junction pathway is associated with the risk for NTDs, and the DNA methylation aberration may be caused by exposure to benzo(a)pyrene.

Using state and provincial surveillance programs to reduce risk of recurrence of neural tube defects in the United States and Canada: A missed opportunity?

BACKGROUND

Once a woman has had a fetus or infant affected with a neural tube defect (NTD), the risk of recurrence is approximately 3%. This risk can be significantly reduced by folic acid supplement consumption during the periconceptional period; however, this requires women at risk to be adequately informed about the appropriate dosage and timing of supplement intake before planning another pregnancy. As birth defects surveillance programs are tasked with identifying and documenting NTD-affected pregnancies and births, they are in a unique position to support recurrence prevention activities.

METHODS

In 2015, we surveyed state and provincial birth defects surveillance programs to assess their NTD recurrence prevention activities. The online survey was sent to programs in 52 United States (U.S.) jurisdictions and all 13 provinces and territories in Canada. Findings were compared with a similar survey conducted in 2005 among U.S. programs.

RESULTS

In 2015, of the 44 U.S. and Canadian surveillance programs that responded, only 9 programs (7 U.S. and 2 Canadian) reported currently having activities specifically directed toward preventing NTD recurrence. Compared with a 2005 survey of U.S. programs, the number of U.S. programs working on NTD recurrence prevention decreased by almost 50% (from 13 to 7 programs).

CONCLUSION

The number of birth defects surveillance programs with NTD recurrence prevention activities has decreased over the past decade due to a range of barriers, most notably a lack of resources. However, while some recurrence prevention activities require part-time staff, other activities could be accomplished using minimal resources. Birth Defects Research (Part A) 106:875-880, 2016.© 2016 Wiley Periodicals, Inc.

Proportion of selected congenital heart defects attributable to recognized risk factors

PURPOSE

To assess the contribution of multiple risk factors for two congenital heart defects-hypoplastic left heart syndrome (HLHS) and tetralogy of Fallot (TOF).

METHODS

We used data from the National Birth Defects Prevention Study (1997-2011) to estimate average adjusted population attributable fractions for several recognized risk factors, including maternal prepregnancy overweight-obesity, pregestational diabetes, age, and infant sex.

RESULTS

There were 594 cases of isolated simple HLHS, 971 cases of isolated simple TOF, and 11,829 controls in the analysis. Overall, 57.0% of HLHS cases and 37.0% of TOF cases were estimated to be attributable to risk factors included in our model. Among modifiable HLHS risk factors, maternal prepregnancy overweight-obesity accounted for the largest proportion of cases (6.5%). Among modifiable TOF risk factors, maternal prepregnancy overweight-obesity and maternal age of 35 years or older accounted for the largest proportions of cases (8.3% and 4.3%, respectively).

CONCLUSIONS

Approximately half of HLHS cases and one-third of TOF cases were estimated to be attributable to risk factors included in our models. Interventions targeting factors that can be modified may help reduce the risk of HLHS and TOF development. Additional research into the etiology of HLHS and TOF may reveal other modifiable risk factors that might contribute to primary prevention efforts.