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

Effect of post-gastrulation exposure to acrylamide on chick embryonic development

The critical developmental stages of the embryo are strongly influenced by the dietary composition of the mother. Acrylamide is a food contaminant that can form in carbohydrate-rich foods that are heat-treated. The aim of this study was to investigate the toxicity of a relatively low dose of acrylamide on the development of the neural tube in the early stage chick embryos. Specific pathogen-free fertilized eggs (n = 100) were treated with acrylamide (0.1, 0.5, 2.5, 12.5 mg/kg) between 28-30th hours of incubation and dissected at 48th hours. In addition to morphological and histopathological examinations, proliferating cell nuclear antigen (PCNA) and caspase 3 were analyzed immunohistochemically. The brain and reproductive expression gene (BRE) was analyzed by RT-PCR. Acrylamide exposure had a negative effect on neural tube status even at a very low dose (0.1 mg/kg) (p < 0.05). Doses of 0.5 mg/kg and above caused a delay in neural tube development (p < 0.05). Crown-rump length and somite count decreased dose-dependently, while this decrease was not significant in the very low dose group (p > 0.05), which was most pronounced at doses of 2.5 and 12.5 mg/kg (p < 0.001). Acrylamide exposure dose-dependently decreased PCNA and increased caspase 3, with this change being significant at doses of 0.5 mg/kg and above (p < 0.001). BRE was downregulated at all acrylamide exposures except in the very low dose group (0.1 mg/kg). In conclusion, we find that acrylamide exposure (at 0.5 mg/kg and above) in post-gastrulation delays neural tube closure in chicken embryos by suppressing proliferation and apoptosis induction and downregulating BRE gene expression.

Up-regulation of miR-10a-5p expression inhibits the proliferation and differentiation of neural stem cells by targeting Chl1

Neural tube defects (NTDs) are characterized by the failure of neural tube closure during embryogenesis and are considered the most common and severe central nervous system anomalies during early development. Recent microRNA (miRNA) expression profiling studies have revealed that the dysregulation of several miRNAs plays an important role in retinoic acid (RA)-induced NTDs. However, the molecular functions of these miRNAs in NTDs remain largely unidentified. Here, we show that miR-10a-5p is significantly upregulated in RA-induced NTDs and results in reduced cell growth due to cell cycle arrest and dysregulation of cell differentiation. Moreover, the cell adhesion molecule L1-like ( Chl1) is identified as a direct target of miR-10a-5p in neural stem cells (NSCs) in vitro, and its expression is reduced in RA-induced NTDs. siRNA-mediated knockdown of intracellular Chl1 affects cell proliferation and differentiation similar to those of miR-10a-5p overexpression, which further leads to the inhibition of the expressions of downstream ERK1/2 MAPK signaling pathway proteins. These cellular responses are abrogated by either increased expression of the direct target of miR-10a-5p ( Chl1) or an ERK agonist such as honokiol. Overall, our study demonstrates that miR-10a-5p plays a major role in the process of NSC growth and differentiation by directly targeting Chl1, which in turn induces the downregulation of the ERK1/2 cascade, suggesting that miR-10a-5p and Chl1 are critical for NTD formation in the development of embryos.

Docosahexaenoic acid, eicosapentaenoic acid, arachidonic acid, and neural tube defects in Tunisian population

OBJECTIVE

To determine the effect of maternal status in (plasma and red blood cell) folate, vitamin B12, homocysteine, and vitamin D, as well as their interaction with MTHFR (C677T and A1298C) and MTRR A66G polymorphisms, on maternal plasma docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) levels and the risk of neural tube defects (NTDs).

METHODS

ARA, EPA, and DHA composition was assessed using capillary gas chromatography.

RESULTS

ARA and DHA levels were higher in controls than in case mothers for low plasma folate status. For low red blood cell folate status, DHA levels were higher in controls than in case mothers. For high homocysteine levels, ARA and DHA levels were higher in controls than in case mothers. NTD mothers had lower EPA and DHA levels for low vitamin B12 levels. NTD mothers had lower DHA levels for low vitamin D levels. For low plasma folate status, DHA levels in the MTHFR C677T gene and ARA and EPA levels in MTHFR A1298C gene were different among the three genotypes in case mothers. DHA levels in the MTHFR C677T gene were different among the three genotypes in case mothers for both low and high homocysteine levels. For low vitamin B12 levels, ARA and DHA levels were different among the three genotypes of the MTHFR C677T gene in case mothers. In the MTHFR C677T gene, ARA and DHA levels were different among the three genotypes in case mothers for low vitamin D levels.

CONCLUSIONS

More advanced research is required to verify a suitable biochemical parameter status in relation to the genotypes in pregnant women.

Association of spinal cord abnormalities with vertebral anomalies: an embryological perspective

PURPOSE

To analyze the relationship between spinal cord and vertebral abnormalities from the point of view of embryology.

METHODS

We analyzed the clinical and radiological data of 260 children with different types of spinal cord malformations in combination with vertebral abnormalities.

RESULTS

Among 260 individuals, approximately 109 presented with open neural tube defects (ONTDs), 83 with split cord malformations (SCMs), and 83 with different types of spinal lipomas. Pathological spina bifida emerged as the most frequent vertebral anomaly, affecting 232 patients, with a higher prevalence in ONTD. Vertebral segmentation disorders, including unsegmented bars, butterfly vertebrae, and hemivertebrae, were present in 124 cases, with a higher prevalence in SCM. The third most common spinal anomaly group consisted of various forms of sacral agenesis (58 cases), notably associated with blunt conus medullaris, spinal lipomas, and sacral myelomeningocele. Segmental aplasia of the spinal cord had a typical association with segmental spinal absence (N = 17).

CONCLUSION

The association between SCM and neuroenteric cyst/canal and vertebral segmentation disorders is strong. High ONTDs often coincide with pathological spina bifida posterior. Type 1 spinal lipomas and focal spinal nondisjunction also correlate with pathologic spina bifida. Segmental spinal absence or dysgenesis involves localized spinal and spinal cord aplasia, sometimes with secondary filar lipoma.

Planar Cell Polarity Signaling: Coordinated Crosstalk for Cell Orientation

The planar cell polarity (PCP) system is essential for positioning cells in 3D networks to establish the proper morphogenesis, structure, and function of organs during embryonic development. The PCP system uses inter- and intracellular feedback interactions between components of the core PCP, characterized by coordinated planar polarization and asymmetric distribution of cell populations inside the cells. PCP signaling connects the anterior-posterior to left-right embryonic plane polarity through the polarization of cilia in the Kupffer's vesicle/node in vertebrates. Experimental investigations on various genetic ablation-based models demonstrated the functions of PCP in planar polarization and associated genetic disorders. This review paper aims to provide a comprehensive overview of PCP signaling history, core components of the PCP signaling pathway, molecular mechanisms underlying PCP signaling, interactions with other signaling pathways, and the role of PCP in organ and embryonic development. Moreover, we will delve into the negative feedback regulation of PCP to maintain polarity, human genetic disorders associated with PCP defects, as well as challenges associated with PCP.

Neural tube defects and epigenetics: role of histone post-translational histone modifications

Neural tube defects (NTDs) are the most common congenital anomalies of the CNS. It is widely appreciated that both genetic and environmental factors contribute to their etiology. The inability to ascribe clear genetic patterns of inheritance to various NTD phenotypes suggests it is possible that epigenetic mechanisms are involved in the etiology of NTDs. In this context, the contribution of DNA methylation as an underlying contributing factor to the etiology of NTDs has been extensively reviewed. Here, an updated accounting of the evidence linking post-translational histone modifications to these birth defects, relying heavily upon studies in humans, and the possible molecular implications inferred from reports based on cellular and animal models, are presented.

Exploring the life experiences of school-aged children afflicted by tethered spinal cord syndrome: An interpretative qualitative study

BACKGROUND

Children affected by tethered cord syndrome (TCS) encounter multifaceted challenges encompassing educational, familial and social spheres, underscoring the significance of a holistic comprehension of their subjective emotional well-being and life encounters. Nonetheless, healthcare professionals tend to prioritise the physical functionality of the afflicted individuals throughout the treatment and rehabilitation process, often neglecting the emotional experiences and requirements of these children as they transition into posthospitalization phases.

AIM

To advance the subjective experiences and perceptions of children with TCS upon reintegration into their families, educational institutions and wider societal contexts subsequent to their discharge from medical facilities.

METHODS

The study was conducted at the Children's Hospital in Zhejiang. Twelve children aged 8-15 with TCS were included in the study. The research design used an interpretative qualitative approach, utilising semi-structured interviews as the primary data collection method. Data analysis was performed using reflexive thematic analysis, facilitating a comprehensive exploration of emerging themes and patterns.

RESULTS

Four major themes (and seven subthemes) were identified from the findings: (1) growing pains (a shameful secret, distance between ideal and reality); (2) inappropriate expressions of familial affection (knowing is not understanding, unspeakable guilt); (3) social estrangement (uncomfortable distinctions, familiar stranger) and (4) striving for independence and consistency.

CONCLUSIONS

Children affected by TCS exhibit internal sensitivity and challenges in self-development, family dynamics and social interactions. They aspire to attain a future characterised by independence and freedom, akin to that of their typically developing peers. These findings can help health professionals, families and educators gain a deeper understanding of what it takes to be a child with TCS, and the findings can also serve as a platform for interventions that seek to promote self-expression in these children so that they can experience life as a meaningful and positive process.

PATIENT OR PUBLIC CONTRIBUTION

This study received support from children with TCS and their guardians during data collection, as well as from the head nurse of the unit. Coresearchers also contributed to design, data collection, analysis and writing.

Folic acid supplementation in women of childbearing age with epilepsy: No association with type or number of antiepileptic drugs

BACKGROUND

For over two decades, a daily folic acid (FA) supplementation has been recommended for women of childbearing age with epilepsy. This recommendation is based on evidence that FA administration before conception and during pregnancy can decrease the risk of fetal malformations in the general population, improve cognitive development, and reduce the risk of autistic traits in children exposed in utero to antiepileptic drugs (AEDs).

OBJECTIVE

The aim of this study was to evaluate FA supplementation rate in nonpregnant women of childbearing age with epilepsy and its relation to AED type and number.

METHODS

We retrospectively reviewed the computerized database and the medical records of all the women who had a first visit to our outpatient epilepsy clinic (Shamir-Assaf Harofeh Medical Center, Zerifin, Israel) during a 10-year period (2012-2021).

RESULTS

Only 61 (22%) of 282 nonpregnant women of childbearing age with epilepsy treated with AEDs received FA supplementation. Ninety-two (33%) of the women were treated with AED polytherapy, and 41 (15%) received valproic acid in monotherapy or polytherapy. FA supplementation rate was higher in women aged ≤40 versus >40 (25% vs. 8.5%) (p = .004). No correlation was found between FA supplementation and AED type or number.

CONCLUSIONS

FA supplementation rate was low and was unaffected by AED treatment. Patient and physician-targeted interventions should be implemented to increase FA prescription and patient adherence.

Associations between maternal stressful life events experiences and risk of neural tube defects in offspring: a systematic review and meta-analysis

OBJECTIVES

Multiple factors associated with neural tube defects (NTDs) risk have been identified, yet there is little evidence on the possible effects of maternal stressful life events. In this study, we aimed to investigate the association between stressful life events during the periconceptional period and risk of NTDs in offspring.

METHODS

Relevant literature was searched in PubMed, Springer Link, ScienceDirect, and Cochrane Library up to July 2023. The pooled odds ratio (OR) and 95% confidence interval (CI) of NTDs risk with maternal stressful life events were estimated using a random effects model. Publication bias was assessed using Egger's regression asymmetry test and Begg's rank correlation test with Begg's funnel plot.

RESULTS

Analysis results showed that mothers who experienced stressful life events during the periconceptional period were at greater risk of having NTDs offspring (OR: 1.37, 95% CI: 1.08-1.73) than those who did not. In subgroup analysis, the pooled OR was 1.37 (1.13-1.67) and 1.73 (0.36-8.32) for with and without adjusting for folic acid supplementation in each included study, while was 1.37 (1.13-1.67) and 1.64 (0.39-6.88) for exposure time of three months preconception until three months post conception and one year preconception until three months post conception, respectively.

CONCLUSIONS

This study suggests that maternal stressful life events during the periconceptional period are significantly associated with higher NTDs risk in offspring. Tailored approaches for evaluating the risk and policy of NTDs among women of childbearing age should emphasize individual stressful experiences before and during early pregnancy.

Analysis of Gut Characteristics and Microbiota Changes with Maternal Supplementation in a Neural Tube Defect Mouse Model

Adequate nutrient supply is crucial for the proper development of the embryo. Although nutrient supply is determined by maternal diet, the gut microbiota also influences nutrient availability. While currently there is no cure for neural tube defects (NTDs), their prevention is largely amenable to maternal folic acid and inositol supplementation. The gut microbiota also contributes to the production of these nutrients, which are absorbed by the host, but its role in this context remains largely unexplored. In this study, we performed a functional and morphological analysis of the intestinal tract of loop-tail mice (Vangl2 mutants), a mouse model of folate/inositol-resistant NTDs. In addition, we investigated the changes in gut microbiota using 16S rRNA gene sequencing regarding (1) the host genotype; (2) the sample source for metagenomics analysis; (3) the pregnancy status in the gestational window of neural tube closure; (4) folic acid and (5) D-chiro-inositol supplementation. We observed that Vangl2+/Lp mice showed no apparent changes in gastrointestinal transit time or fecal output, yet exhibited increased intestinal length and cecal weight and gut dysbiosis. Moreover, our results showed that the mice supplemented with folic acid and D-chiro-inositol had significant changes in their microbiota composition, which are changes that could have implications for nutrient absorption.

Maternal Folic Acid Supplementation Improves the Intestinal Health of Offspring Porcine by Promoting the Proliferation and Differentiation of Intestinal Stem Cells

Maternal folic acid intake has important effects on offspring growth and development. The mechanism involved in the renewal of intestinal epithelial cells remains unclear. Thus, this study aimed to investigate the potential effect of maternal folic acid supplementation during gestation and lactation on the structural and functional development of the small intestine in piglet offspring. Twenty-four Duroc sows were assigned to a control group (CON) and a folic-acid-supplemented group (CON + FA, supplemented with 15 mg/kg of folic acid). The results showed that maternal folic acid supplementation throughout gestation and lactation significantly increased the body weight, serum folate level, and intestinal folate metabolism in piglets. It also improved the villus length, villus height-to-crypt depth ratio, and transcript levels of nutrient transporters (GLUT4, SNAT2, FABP2, and SLC7A5) in piglets' duodenum and jejunum. In addition, maternal folic acid supplementation increased Ki67-positive cells and the expression of proliferation-related marker genes (C-Myc, CyclinD1, and PCNA) in piglets' intestinal stem cells. It also boosted the expression of genes associated with mature secreted cells (ChrA, Muc2, Lyz, Vil1), indicating enhanced proliferation and differentiation of intestinal stem cells. These findings demonstrate that maternal folic acid supplementation enhances growth performance and gut health in piglet offspring by promoting epithelial cell renewal equilibrium.

Strengthening the Evidence: Similar Rates of Neural Tube Defects Among Deliveries Regardless of Maternal HIV Status and Dolutegravir Exposure in Hospital Birth Surveillance in Eswatini

Birth defect surveillance in Eswatini in 2020-2021 identified 0.80% defects (197/24 599 live and stillborn infants). Neural tube defect (NTD) prevalence was 0.08%, 0.08%, and 0.15% for 4902 women on dolutegravir preconception, 17 285 HIV-negative women, and 1320 women on efavirenz preconception, respectively, more definitively refuting the dolutegravir preconception NTD safety signal.