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

Red blood cell folate and benign prostatic hyperplasia: results from the NHANES 2001-2008

BACKGROUND

Benign prostatic hyperplasia (BPH) affects 30% of men worldwide, folate is essential for life. However, few studies have investigated the relationship between folate levels and BPH. The present study aims to explore the relationship between red blood cell (RBC) folate, a better indicator of long-term folate intake, and BPH in United States (US) men.

METHODS

We used statistics from four cycles of the "National Health and Nutrition Examination Survey" (NHANES2001-2008), RBC folate data come from laboratory data and BPH date come from questionnaire data. A multivariate conditional logistic regression model and subgroup analysis were using to assess the association between RBC folate and BPH.

RESULTS

647 males from four survey cycles in the NHANES2001-2008, of which, 574 men (88.7%) had BPH. After adjusting for potential confounders, a considerable correlation was observed between RBC folate and BPH; With the first quintiles of RBC folate as the reference, multivariable-adjusted odds ratios (ORs) and confidence intervals (95% CIs) of the second, third, fourth, and the highest quintiles were 1.19 (0.58 ∼ 2.44), 1.39 (0.65 ∼ 2.97), 2.27 (0.96 ∼ 5.39), 2.26 (1.35 ∼ 3.76) and 5.37 (1.85 ∼ 15.59), respectively.

CONCLUSIONS

Individuals with high levels of RBC folate were associated with an increased risk of self-reported benign prostatic hyperplasia of US men.

P-aminobenzoic acid promotes retinal regeneration through activation of Ascl1a in zebrafish

JOURNAL/nrgr/04.03/01300535-202408000-00040/figure1/v/2023-12-16T180322Z/r/image-tiff The retina of zebrafish can regenerate completely after injury. Multiple studies have demonstrated that metabolic alterations occur during retinal damage; however to date no study has identified a link between metabolites and retinal regeneration of zebrafish. Here, we performed an unbiased metabolome sequencing in the N-methyl-D-aspartic acid-damaged retinas of zebrafish to demonstrate the metabolomic mechanism of retinal regeneration. Among the differentially-expressed metabolites, we found a significant decrease in p-aminobenzoic acid in the N-methyl-D-aspartic acid-damaged retinas of zebrafish. Then, we investigated the role of p-aminobenzoic acid in retinal regeneration in adult zebrafish. Importantly, p-aminobenzoic acid activated Achaetescute complex-like 1a expression, thereby promoting Müller glia reprogramming and division, as well as Müller glia-derived progenitor cell proliferation. Finally, we eliminated folic acid and inflammation as downstream effectors of PABA and demonstrated that PABA had little effect on Müller glia distribution. Taken together, these findings show that PABA contributes to retinal regeneration through activation of Achaetescute complex-like 1a expression in the N-methyl-D-aspartic acid-damaged retinas of zebrafish.

Women in Canada are consuming above the upper intake level of folic acid but few are meeting dietary choline recommendations in the second trimester of pregnancy: data from the CHILD cohort study

There is concern that during a low-risk pregnancy, women are consuming more than recommended (400 µg/day) supplemental folic acid and may not meet recommendations for other nutrients. The objective of this study was to determine folic acid supplement use and dietary folate intakes in the second trimester (week 18) of pregnancy in women (n = 2996) in the Canadian CHILD cohort study. Vitamin B12 and choline intakes were also assessed because they are metabolically related to folate. The majority of participants (71.6%) were consuming a daily prenatal supplement. Twenty-eight percent of women (n = 847) reported consuming a folic acid supplement and of these women, 45.3% had daily supplemental folic acid intakes above the upper intake level (UL; 1000 µg/day). Daily dietary folate intakes were (mean (SD)) 575 (235) DFE µg/day. In contrast, only 24.8% of women met the dietary choline adequate intake (AI) recommendation (AI ≥ 450 mg/day) with a mean (SD) intake of 375 (151) mg/day. Further understanding of the impact of supplemental folic acid intake above the UL and low choline intake during pregnancy requires further investigation.

Dolutegravir induces FOLR1 expression during brain organoid development

During the first month of pregnancy, the brain and spinal cord are formed through a process called neurulation. However, this process can be altered by low serum levels of folic acid, environmental factors, or genetic predispositions. In 2018, a surveillance study in Botswana, a country with a high incidence of human immunodeficiency virus (HIV) and lacking mandatory food folate fortification programs, found that newborns whose mothers were taking dolutegravir (DTG) during the first trimester of pregnancy had an increased risk of neural tube defects (NTDs). As a result, the World Health Organization and the U.S. Food and Drug Administration have issued guidelines emphasizing the potential risks associated with the use of DTG-based antiretroviral therapies during pregnancy. To elucidate the potential mechanisms underlying the DTG-induced NTDs, we sought to assess the potential neurotoxicity of DTG in stem cell-derived brain organoids. The gene expression of brain organoids developed in the presence of DTG was analyzed by RNA sequencing, Optical Coherence Tomography (OCT), Optical Coherence Elastography (OCE), and Brillouin microscopy. The sequencing data shows that DTG induces the expression of the folate receptor (FOLR1) and modifies the expression of genes required for neurogenesis. The Brillouin frequency shift observed at the surface of DTG-exposed brain organoids indicates an increase in superficial tissue stiffness. In contrast, reverberant OCE measurements indicate decreased organoid volumes and internal stiffness.

FIGO Preconception Checklist: Preconception care for mother and baby

The preconception period is a unique and opportunistic time in a woman's life when she is motivated to adopt healthy behaviors that will benefit her and her child, making this time period a critical "window of opportunity" to improve short- and long-term health. Improving preconception health can ultimately improve both fetal and maternal outcomes. Promoting health before conception has several beneficial effects, including an increase in seeking antenatal care and a reduction in neonatal mortality. Preconception health is a broad concept that encompasses the management of chronic diseases, including optimal nutrition, adequate consumption of folic acid, control of body weight, adoption of healthy lifestyles, and receipt of appropriate vaccinations. Use of the FIGO Preconception Checklist, which includes the key elements of optimal preconception care, will empower women and their healthcare providers to better prepare women and their families for pregnancy.

Surviving against the odds: exploring the clinical and radiological features of iniencephaly compatible with life. Illustrative case

BACKGROUND

Iniencephaly is a rare neural tube defect (NTD) characterized by deformities in the occiput and inion, along with rachischisis in the cervical and thoracic spine, resulting in the head appearing in retroflexion.

OBSERVATIONS

This report details the case of a female newborn who underwent surgery for an encephalocele. She survived up to 6 months, exhibiting good overall health, although she displayed physical abnormalities, including facial deformity, a short neck, and minor spasms in all limbs. Both cardiovascular and abdominal assessments remained stable, and imaging revealed defects in the occipital bone, a large cephalocele, and spinal dysraphism.

LESSONS

Although iniencephaly is generally incompatible with life, a few cases have been reported otherwise. Our patient, one of these notable exceptions, remains alive at 6 months old, possibly due to the lack of major vascular deformities. However, she does exhibit significant psychomotor retardation.

Update on the impact of voluntary folic acid fortification of corn masa flour on red blood cell folate concentrations-National Health and Nutrition Examination Survey, 2011-March 2020

BACKGROUND

Folic acid is a micronutrient that is effective at preventing neural tube defects (NTDs). In 2016, the FDA authorized the voluntary fortification of corn masa flour (CMF) with folic acid to reduce disparities in NTDs among infants of women who do not regularly consume other fortified cereal grains, in particular Hispanic women of reproductive age (WRA).

METHODS

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to March 2020 assessing the impact of voluntary fortification of CMF on the folate status of Hispanic WRA. We analyzed folic acid usual intake and red blood cell (RBC) folate concentrations among non-pregnant, non-lactating Hispanic WRA, comparing pre-fortification (2011-2016) to post-fortification (2017-March 2020) data. RBC folate concentrations were used to create model-based estimation of NTD rates.

RESULTS

The proportion of Hispanic WRA with folic acid usual intakes <400 μg/d did not change (2011-2016: 86.1% [95% Confidence Interval, CI: 83.7-88.5]; 2017-March 2020: 87.8% [95% CI: 84.8-90.7]; p = .38) nor did the proportion of Hispanic WRA with RBC folate below optimal concentrations (<748 nmol/L, 2011-2016: 16.0% [95% CI: 13.7-18.2]; 2017-March 2020: 18.1% [95% CI: 12.1-24.0]; p = 0.49). Model-based estimates of NTD rates suggest further improvements in the folate status of Hispanic WRA might prevent an additional 157 (95% Uncertainty Interval: 0, 288) NTDs/year.

CONCLUSIONS

Voluntary fortification of CMF with folic acid has yet to have a significant impact on the folate status of WRA. Continued monitoring and further research into factors such as fortified product availability, community knowledge, and awareness of folic acid benefits would inform and improve future public health interventions.

Genome-wide analysis of spina bifida risk variants in a case-control study from Bangladesh

BACKGROUND

Human studies of genetic risk factors for neural tube defects, severe birth defects associated with long-term health consequences in surviving children, have predominantly been restricted to a subset of candidate genes in specific biological pathways including folate metabolism.

METHODS

In this study, we investigated the association of genetic variants spanning the genome with risk of spina bifida (i.e., myelomeningocele and meningocele) in a subset of families enrolled from December 2016 through December 2022 in a case-control study in Bangladesh, a population often underrepresented in genetic studies. Saliva DNA samples were analyzed using the Illumina Global Screening Array. We performed genetic association analyses to compare allele frequencies between 112 case and 121 control children, 272 mothers, and 128 trios.

RESULTS

In the transmission disequilibrium test analyses with trios only, we identified three novel exonic spina bifida risk loci, including rs140199800 (SULT1C2, p = 1.9 × 10-7), rs45580033 (ASB2, p = 4.2 × 10-10), and rs75426652 (LHPP, p = 7.2 × 10-14), after adjusting for multiple hypothesis testing. Association analyses comparing cases and controls, as well as models that included their mothers, did not identify genome-wide significant variants.

CONCLUSIONS

This study identified three novel single nucleotide polymorphisms involved in biological pathways not previously associated with neural tube defects. The study warrants replication in larger groups to validate findings and to inform targeted prevention strategies.

Exposure to pesticides during pregnancy and the risk of neural tube defects: A systematic review

Exposure to pesticides during pregnancy has been associated with several serious congenital malformations, such as neural tube defects, therefore, is a cause for concern in terms of human health. This review aims to gather information related to maternal exposure during pregnancy and the risk of triggering neural tube defects in the offspring. The search strategy for the studies followed the PRISMA guidelines. We conducted a systematic search in the Science Direct, PubMed, Cochrane Library, Embase, Scopus, and Web of Science databases for all epidemiological studies that sought to associate exposure to pesticides during embryonic development with the risk of neural tube defects (NTDs). The keywords used were "pesticide", "herbicide", "congenital" and "neural". Of the 229 articles, 8 eligible ones (7 case-control and 1 cross-sectional) evaluated pesticide exposure in pregnancy. Different methods were used, including analysis of biological samples and questionnaires. The pesticides studied included insecticides, herbicides, fungicides, and nematicides. Insecticides were the most studied, with variations in concentrations between tissues and studies. Distinct levels of pesticides have been detected in maternal serum, placenta, and umbilical cord. Models were statistically adjusted for confounding factors, such as smoking and dietary supplement intakes. Concentrations were measured in different exposure windows (periconception and prenatal), related to NTDs such as anencephaly and spina bifida. Different data collection techniques, types of biological samples, and exposure windows were used, which made comparison difficult. The main pesticides studied included DDT, DDE, HCH, and endosulfan. Maternal serum showed the highest concentrations of pesticides, but detection in placental tissue and umbilical cord confirms embryonic exposure. Confounding variables were adjusted for in the analysis of the articles, but they may still contribute to the risk of NTDs. All the studies analyzed pesticide exposure and the relationship with NTDs. However, a more standardized survey would be ideal for better comparisons.

National Diet and Nutrition Survey data reveal a decline in folate status in the United Kingdom population between 2008 and 2019

BACKGROUND

Folate is essential for healthy growth and development. Fortification of foods with folic acid can improve folate status and reduce risk of neural tube defects (NTD). Following concern around folate status in the United Kingdom, the United Kingdom government announced in 2021 the intention to introduce mandatory folic acid fortification.

OBJECTIVE

This study aimed to describe folate status in the United Kingdom population prior to the implementation of mandatory folic acid fortification of non-whole wheat (non-wholemeal) flour and to assess trends in folate status, including in females of reproductive age (FRA).

METHODS

Data were from the United Kingdom National Diet and Nutrition Survey Rolling Program (2008-2019), a cross-sectional, nationally representative survey of children and adults aged 1.5+ (n = 5792 with folate result). Serum folate concentration was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) and red blood cell (RBC) folate concentration by microbiological assay. Concentration data were compared against method-specific cut-offs and thresholds, and relationships were explored against demographic and lifestyle characteristics.

RESULTS

RBC and serum folate concentration significantly decreased by ∼3 percentage points per year between 2008 and 2019 in all age/sex groups. Prevalence of deficiency (RBC folate < 305 nmol/L) was highest in children aged 11 to 18 y (17% in 2016-2019). The proportion of FRA below the cut-off for increased risk of NTD (RBC folate < 748 nmol/L) increased from 69% to 89% between 2008 and 2019. Ethnicity, smoking status, and income were significant determinants of RBC and serum folate concentrations.

CONCLUSIONS

These data reveal a decline in population folate status in the United Kingdom between 2008 and 2019 and a high prevalence of folate deficiency. A high proportion of FRA had RBC folate concentrations below the cut-off for increased risk of NTD. These data provide information on folate status in a population not currently exposed to mandatory folic acid fortification and are essential to model and assess its impact.

Parental folic acid deficiency delays neurobehavioral development in rat offspring by inhibiting the differentiation of neural stem cells into neurons

Maternal folate status during pregnancy is associated with the neurodevelopment of offspring; however, study results on the association between paternal folate status and offspring neurodevelopment are inconsistent. This study aimed to explore whether parental folic acid deficiency affects the neurobehavioral development of offspring by affecting the differentiation of neural stem cells (NSCs) into neurons. In the present study, the offspring were divided into four groups: parental folic acid deficient group (D-D), maternal folic acid deficient and paternal folic acid normal group (D-N), maternal folic acid normal and paternal folic acid deficient group (N-D), and parental folic acid normal group (N-N). For in vivo study, neurobehavioral indexes, and neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) expression in the brain hippocampus and cerebral cortex of offspring were measured at different time points. For in vitro study, NSCs were cultured from the hippocampus and striatum, and neuronal and astrocytic differentiation were measured. The results demonstrated that parental folic acid deficiency decreased the brain folate level in offspring, delayed early sensory-motor reflex development, impaired spatial learning and memory ability in adolescence and adulthood, decreased differentiation of NSCs into neurons and increased differentiation of NSCs into astrocytes in vivo and in vitro. These impacts on the neurodevelopment of offspring were most pronounced in D-D group, followed by D-N group and N-D group. In conclusion, parental folic acid deficiency inhibits the neurobehavioral development of offspring, possibly by inhibiting the differentiation of NSCs into neurons.

Folic acid supplementation in a mouse model of diabetes in pregnancy alters insulin sensitivity in female mice and beta cell mass in offspring

Epidemiological studies have reported discrepant findings on the relationship between folic acid intake during pregnancy and risk for gestational diabetes mellitus (GDM). To begin to understand how folic acid impacts metabolic health during pregnancy, we determined the effects of excess folic acid supplementation (5× recommendation) on maternal and fetal offspring metabolic health. Using a mouse (female C57BL/6J) model of diet-induced diabetes in pregnancy (western diet) and control mice, we show that folic acid supplementation improved insulin sensitivity in the female mice fed the western diet and worsened insulin sensitivity in control mice. We found no unmetabolized folic acid in liver from supplemented mice suggesting the metabolic effects of folic acid supplementation are not due to unmetabolized folic acid. Male fetal (gestational day 18.5) offspring from folic acid supplemented dams (western and control) had greater beta cell mass and density than those from unsupplemented dams; this was not observed in female offspring. Differential sex-specific hepatic gene expression profiles were observed in the fetal offspring from supplemented dams but this differed between western and controls. Our findings suggest that folic acid supplementation affects insulin sensitivity in female mice, but is dependent on their metabolic phenotype and has sex-specific effects on offspring pancreas and liver.

Genetic Inheritance Models of Non-Syndromic Cleft Lip with or without Palate: From Monogenic to Polygenic

Non-syndromic cleft lip with or without palate (NSCL/P) is a prevalent birth defect that affects 1/500-1/1400 live births globally. The genetic basis of NSCL/P is intricate and involves both genetic and environmental factors. In the past few years, various genetic inheritance models have been proposed to elucidate the underlying mechanisms of NSCL/P. These models range from simple monogenic inheritance to more complex polygenic inheritance. Here, we present a comprehensive overview of the genetic inheritance model of NSCL/P exemplified by representative genes and regions from both monogenic and polygenic perspectives. We also summarize existing association studies and corresponding loci of NSCL/P within the Chinese population and highlight the potential of utilizing polygenic risk scores for risk stratification of NSCL/P. The potential application of polygenic models offers promising avenues for improved risk assessment and personalized approaches in the prevention and management of NSCL/P individuals.

Precision Nutrition: The Hype Is Exceeding the Science and Evidentiary Standards Needed to Inform Public Health Recommendations for Prevention of Chronic Disease

As dietary guidance for populations shifts from preventing deficiency disorders to chronic disease risk reduction, the biology supporting such guidance becomes more complex due to the multifactorial risk profile of disease and inherent population heterogeneity in the diet-disease relationship. Diet is a primary driver of chronic disease risk, and population-based guidance should account for individual responses. Cascading effects on evidentiary standards for population-based guidance are not straightforward. Precision remains a consideration for dietary guidance to prevent deficiency through the identification of population subgroups with unique nutritional needs. Reducing chronic disease through diet requires greater precision in (a) establishing essential nutrient needs throughout the life cycle in both health and disease; (b) considering effects of nutrients and other food substances on metabolic, immunological, inflammatory, and other physiological responses supporting healthy aging; and (c) considering healthy eating behaviors. Herein we provide a template for guiding population-based eating recommendations for reducing chronic diseases in heterogenous populations.

Association of Maternal Folate Intake and Offspring MTHFD1 and MTHFD2 Genes with Congenital Heart Disease

Existing evidence supported that congenital heart defect (CHD) was associated with a combination of environmental and genetic factors. Based on this, this study aimed at assessing the association of maternal folic acid supplementation (FAS), genetic variations in offspring methylenetetrahydrofolate dehydrogenase (MTHFD)1 and MTHFD2 genes, and their interactions with CHD and its subtypes. A hospital-based case-control study, including 620 cases with CHD and 620 healthy children, was conducted. This study showed that the absence of FAS was significantly associated with an increased risk of total CHD and its subtypes, such as atrial septal defect (ASD). FAS during the first and second trimesters was associated with a significantly higher risk of CHD in offspring compared to FAS during the three months prior to conception. The polymorphisms of offspring MTHFD1 and MTHFD2 genes at rs2236222, rs11849530, and rs828858 were significantly associated with the risk of CHD. Additionally, a significantly positive interaction between maternal FAS and genetic variation at rs828858 was observed for the risk of CHD. These findings suggested that pregnant women should carefully consider the timing of FAS, and individuals with higher genetic risk may benefit from targeted folic acid supplementation as a preventive measure against CHD.

Neural tube defects as a cause of death among stillbirths, infants, and children younger than 5 years in sub-Saharan Africa and southeast Asia: an analysis of the CHAMPS network

BACKGROUND

Neural tube defects are common birth defects resulting in severe morbidity and mortality; they can largely be prevented with periconceptional maternal intake of folic acid. Understanding the occurrence of neural tube defects and their contribution to mortality in settings where their burden is highest could inform prevention and health-care policy. We aimed to estimate the mortality attributed to neural tube defects in seven countries in sub-Saharan Africa and southeast Asia.

METHODS

This analysis used data from the Child Health and Mortality Prevention Surveillance (CHAMPS) network and health and demographic surveillance systems from South Africa, Mozambique, Bangladesh, Kenya, Mali, Ethiopia, and Sierra Leone. All stillbirths and infants and children younger than 5 years who died, who were enrolled in CHAMPS, whose families consented to post-mortem minimally invasive tissue sampling (MITS) between Jan 1, 2017, and Dec 31, 2021, and who were assigned a cause of death by a determination of cause of death panel as of May 24, 2022, were included in this analysis, regardless the cause of death. MITS and advanced diagnostic methods were used to describe the frequency and characteristics of neural tube defects among eligible deaths, identify risk factors, and estimate the mortality fraction and mortality rate (per 10 000 births) by CHAMPS site.

FINDINGS

Causes of death were determined for 3232 stillbirths, infants, and children younger than 5 years, of whom 69 (2%) died with a neural tube defect. Most deaths with a neural tube defect were stillbirths (51 [74%]); 46 (67%) were neural tube defects incompatible with life (ie, anencephaly, craniorachischisis, or iniencephaly) and 22 (32%) were spina bifida. Deaths with a neural tube defect were more common in Ethiopia (adjusted odds ratio 8·09 [95% CI 2·84-23·02]), among female individuals (4·40 [2·44-7·93]), and among those whose mothers had no antenatal care (2·48 [1·12-5·51]). Ethiopia had the highest adjusted mortality fraction of deaths with neural tube defects (7·5% [6·7-8·4]) and the highest adjusted mortality rate attributed to neural tube defects (104·0 per 10 000 births [92·9-116·4]), 4-23 times greater than in any other site.

INTERPRETATION

CHAMPS identified neural tube defects, a largely preventable condition, as a common cause of death among stillbirths and neonatal deaths, especially in Ethiopia. Implementing interventions such as mandatory folic acid fortification could reduce mortality due to neural tube defects.

FUNDING

Bill & Melinda Gates Foundation.

Double whammy: the genetic variants in CECR2 and high Hcy on the development of neural tube defects

Introduction: Neural tube defects (NTDs) are serious congenital malformations. The etiology of NTDs involves both genetic and environmental factors. Loss of CECR2 in mice has been shown to result in NTDs. Our previous study indicated that high homocysteine (HHcy) levels could further reduced the expression level of CECR2. This investigation aims to explore the genetic influence of the chromatin remodeling gene, CECR2, in humans and determine if HHcy can have a synergistic effect on protein expression. Methods: We conducted Next-Generation Sequencing (NGS) of the CECR2 gene in 373 NTD cases and 222 healthy controls, followed by functional assay application to select and evaluate CECR2 missense variants and subsequent Western blotting to identify protein expression levels. Results: From the analysis, we identified nine rare, NTD-specific mutations within the CECR2 gene. Significantly, four missense variants (p.E327V, p.T521S, p.G701R, and p.G868R) were selected via functional screening. The E9.5 mouse ectodermal stem cell line NE-4C, transfected with plasmids expressing p.E327V, p.T521S, p.G868R variants or a recombinant harboring all four (named as 4Mut), exhibited notable reductions in CECR2 protein expression. Furthermore, exposure to homocysteine thiolactone (HTL), an extremely reactive homocysteine metabolite, amplified the reduction in CECR2 expression, accompanied by a significant increase in the apoptotic molecule Caspase3 activity, a potential NTD inducer. Importantly, folic acid (FA) supplementation effectively counteracted the CECR2 expression decline induced by CECR2 mutation and HTL treatment, leading to reduced apoptosis. Discussion: Our observations underscore a synergistic relationship between HHcy and genetic variations in CECR2 concerning NTDs, thereby reinforcing the concept of gene-environment interaction phenomena in NTD etiology.

Estimating the serum folate concentration that corresponds to the red blood cell folate concentration threshold associated with optimal neural tube defects prevention: A population-based biomarker survey in Southern India

BACKGROUND

RBC folate concentrations are monitored at the population level, with a recommended threshold for optimal neural tube defect (NTD) prevention. A corresponding threshold for serum folate has not been established.

OBJECTIVES

This study aimed to estimate the serum folate insufficiency threshold corresponding to the RBC folate threshold for NTD prevention and examine how this threshold is modified by vitamin B12 status.

METHODS

Participants were women (15-40 y; not pregnant or lactating; n = 977) from a population-based biomarker survey in Southern India. RBC folate and serum folate were measured via microbiologic assay. RBC folate deficiency (<305 nmol/L) and insufficiency (<748 nmol/L), serum vitamin B12 deficiency (<148 pmol/L) and vitamin B12 insufficiency (<221 pmol/L), elevated plasma MMA (>0.26 μmol/L), elevated plasma homocysteine (>10.0 μmol/L), and elevated HbA1c (≥6.5%) were evaluated. Bayesian linear models were used to estimate unadjusted and adjusted thresholds.

RESULTS

Compared with adequate vitamin B12 status, the estimated serum folate threshold was higher in participants with serum vitamin B12 deficiency (72.5 vs. 28.1 nmol/L) or vitamin B12 insufficiency (48.7 vs. 24.3 nmol/L) and elevated MMA (55.6 vs. 25.9 nmol/L). The threshold was lower in participants with elevated HbA1c (HbA1c ≥6.5% vs. <6.5%; 21.0 vs. 40.5 nmol/L).

CONCLUSIONS

The estimated serum folate threshold for optimal NTD prevention was similar to previous reports (24.3 vs. 25.6 nmol/L) among participants with sufficient vitamin B12 status. However, this threshold was more than 2-fold higher in participants with vitamin B12 deficiency and substantially higher across all indicators of insufficient vitamin B12 status (<221 pmol/L, elevated MMA, combined B12, impaired vitamin B12 status), and lower in participants with elevated HbA1c. Findings suggest a serum folate threshold for NTD prevention may be possible in some settings; however, it may not be appropriate in populations with high prevalence of vitamin B12 insufficiency. Am J Clin Nutr 2023;xx:xx-xx. This trial was registered at https://clinicaltrials.gov as NCT04048330.

Somitic mesoderm morphogenesis is necessary for neural tube closure during Xenopus development

Neural tube closure is a fundamental process during vertebrate embryogenesis, which leads to the formation of the central nervous system. Defective neural tube closure leads to neural tube defects which are some of the most common human birth defects. While the intrinsic morphogenetic events shaping the neuroepithelium have been studied extensively, how tissues mechanically coupled with the neural plate influence neural tube closure remains poorly understood. Here, using Xenopus laevis embryos, live imaging in combination with loss of function experiments and morphometric analysis of fixed samples we explore the reciprocal mechanical communication between the neural plate and the somitic mesoderm and its impact on tissue morphogenesis. We show that although somitic mesoderm convergent extension occurs independently from neural plate morphogenesis neural tube closure depends on somitic mesoderm morphogenesis. Specifically, impaired somitic mesoderm remodelling results in defective apical constriction within the neuroepithelium and failure of neural tube closure. Last, our data reveal that mild abnormalities in somitic mesoderm and neural plate morphogenesis have a synergistic effect during neurulation, leading to severe neural tube closure defects. Overall, our data reveal that defective morphogenesis of tissues mechanically coupled with the neural plate can not only drastically exacerbate mild neural tube defects that may arise from abnormalities within the neural tissue but can also elicit neural tube defects even when the neural plate is itself free of inherent defects.

Gene-environment interactions underlying the etiology of neural tube defects

Neural tube defects (NTDs) consist of severe structural malformations of the brain and spinal cord and are the second most common structural birth defect in humans, accounting for approximately 2700 affected pregnancies every year in the United States. These numbers are highly significant, considering that birth defects remain a leading cause of infant mortality in the United States, affecting approximately 120,000 babies born annually. Survivors of these congenital malformations face long-term disability and lifelong challenges imposed by severe physical burdens compromising the afflicted individual's overall quality of life. Clearly, birth defects, and especially NTDs remain a global public health challenge, and the source of significant financial repercussions for healthcare systems worldwide. In order to better understand the role gene-environment interactions play in the etiology of NTDs, this chapter provides an overview of NTD phenotypes and their embryonic origins, discusses the genetic landscape of NTDs as it is currently understood, with a focus on experimental models that best illustrate how environmental factors modulate individual susceptibility to these birth defects. As folic acid interventions have proven to be effective in reducing the prevalence of NTDs, the chapter ends with a discussion on the impact that maternal dietary status has on NTD prevalence from a population perspective.

Vitamin B12 (Cobalamin): Its Fate from Ingestion to Metabolism with Particular Emphasis on Diagnostic Approaches of Acquired Neonatal/Infantile Deficiency Detected by Newborn Screening

Acquired vitamin B12 (vB12) deficiency (vB12D) of newborns is relatively frequent as compared with the incidence of inherited diseases included in newborn screening (NBS) of different countries across the globe. Infants may present signs of vB12D before 6 months of age with anemia and/or neurologic symptoms when not diagnosed in asymptomatic state. The possibility of identifying vitamin deficient mothers after their pregnancy during the breastfeeding period could be an additional benefit of the newborn screening. Vitamin supplementation is widely available and easy to administer. However, in many laboratories, vB12D is not included in the national screening program. Optimized screening requires either second-tier testing or analysis of new urine and blood samples combined with multiple clinical and laboratory follow ups. Our scope was to review the physiologic fate of vB12 and the pathobiochemical consequences of vB12D in the human body. Particular emphasis was put on the latest approaches for diagnosis and treatment of vB12D in NBS.