Fetal Neural Tube Defects Research Articles

Interaction between Maternal and Paternal SHMT1 C1420T Predisposes to Neural Tube Defects in the Fetus: Evidence from Case-Control and Family-Based Triad Approaches.

Neural tube defects (NTDs) are caused by the failure of neural tube formation which occurs during early embryonic development. NTDs are the most severe and leading cause of fetal mortality. Serine hydroxymethyl transferase (SHMT1) provides one-carbon units necessary for embryogenesis and defects in one-carbon production result in specific pathological conditions during pregnancy. The present study is aimed to evaluate the association of SHMT1 C1420T with NTD risk in the fetus using fetal, maternal and paternal groups by applying both case-control and family-based triad approaches. A total of 924 subjects including 124 NTD case-parent trios (n = 124 × 3 = 372) and 184 healthy control-parent trios (n = 184 × 3 = 552) from Telangana State, South India were analyzed. DNA from umbilical cord tissues and parental blood samples were extracted, and genotyped by polymerase chain reaction-restriction fragment length polymorphism. Statistical analysis used were SPSS, parent-of-origin effect (POE) analysis. Case-control study design demonstrated fetuses with homozygous variant genotype (TT) to be at risk toward spina bifida subtype (p = 0.022). Among parents, fathers with TT genotype were associated with anencephaly (p = 0.018) and spina bifida subtypes (p = 0.027) in the offspring. Of interest, maternal-paternal-offspring genotype incompatibility revealed maternal CT genotype in combination with paternal TT genotype increased risk for NTDs in the fetus (CTxTT = TT; p = 0.021). Family-based parent-of-origin effect linkage analysis revealed significant maternal over-transmission of variant allele to NTD fetuses (p < 0.01). The present study, using both case-control and family-based triad approach is the first report to demonstrate parental association of SHMT1 C1420T variant in conferring NTD risk in the fetus. Birth Defects Research 109:1020-1029, 2017. © 2017 Wiley Periodicals, Inc.

Simple coupled ultrahigh performance liquid chromatography and ion chromatography technique for simultaneous determination of folic acid and inorganic anions in folic acid tablets

Folic acid plays a significant role during periods of rapid cells division and growth. Pregnant women require folic acid daily, either from dietary supplements or folic acid tablets in order to prevent fetal neural tube defects. In this work, a simple coupled ultrahigh performance liquid chromatography and ion chromatography technique was developed for simultaneous determination of folic acid and inorganic anions in folic acid tablets. A reversed-phase C18 column was used as the pretreatment column for on-line separating inorganic anions from organics. Inorganic anions were concentrated in the concentration column. Under the optimal chromatographic conditions, good sensitivity and linear calibration-curves (r≥0.9992) were obtained. Low detection limits were obtained in the range of 0.0032–0.40mgL−1 for all analytes. Repeatability results were satisfactory with relative standard deviations less than 1.50% (n=5). The developed method was utilized to analyze spiked folic acid tablet samples with good measured recoveries (92.4–107.4%).

Interaction between Maternal and Paternal SHMT1 C1420T Predisposes to Neural Tube Defects in the Fetus: Evidence from Case-Control and Family-Based Triad Approaches.

Neural tube defects (NTDs) are caused by the failure of neural tube formation which occurs during early embryonic development. NTDs are the most severe and leading cause of fetal mortality. Serine hydroxymethyl transferase (SHMT1) provides one-carbon units necessary for embryogenesis and defects in one-carbon production result in specific pathological conditions during pregnancy. The present study is aimed to evaluate the association of SHMT1 C1420T with NTD risk in the fetus using fetal, maternal and paternal groups by applying both case-control and family-based triad approaches. A total of 924 subjects including 124 NTD case-parent trios (n = 124 × 3 = 372) and 184 healthy control-parent trios (n = 184 × 3 = 552) from Telangana State, South India were analyzed. DNA from umbilical cord tissues and parental blood samples were extracted, and genotyped by polymerase chain reaction-restriction fragment length polymorphism. Statistical analysis used were SPSS, parent-of-origin effect (POE) analysis. Case-control study design demonstrated fetuses with homozygous variant genotype (TT) to be at risk toward spina bifida subtype (p = 0.022). Among parents, fathers with TT genotype were associated with anencephaly (p = 0.018) and spina bifida subtypes (p = 0.027) in the offspring. Of interest, maternal-paternal-offspring genotype incompatibility revealed maternal CT genotype in combination with paternal TT genotype increased risk for NTDs in the fetus (CTxTT = TT; p = 0.021). Family-based parent-of-origin effect linkage analysis revealed significant maternal over-transmission of variant allele to NTD fetuses (p < 0.01). The present study, using both case-control and family-based triad approach is the first report to demonstrate parental association of SHMT1 C1420T variant in conferring NTD risk in the fetus. Birth Defects Research, 2017. © 2017 Wiley Periodicals, Inc.

Myoinositol: The Bridge (PONTI) to Reach a Healthy Pregnancy.

The use of folic acid in the periconceptional period can prevent about 70% of neural tube defects (NTDs). In the remaining cases, no medical prevention is available, and those conditions should be defined as folate-resistant NTDs. Rodent models suggest that some folate-resistant NTDs can be prevented by inositol (myoinositol and chiroinositol) supplementation prior to pregnancy. Should folic acid be combined with myoinositol periconceptional supplementation to reduce the overall risk of NTDs even in humans? Hereafter, we discuss the results from the PONTI study that strongly support both the effectiveness and safety of myoinositol periconceptional supplementation in preventing human NTDs. We further report on the largest case series of pregnancies treated with myoinositol and folic acid. At our institution, a sequential study during 12 years involved mothers at risk of fetal NTDs, and 29 babies from 27 pregnancies were born after periconceptional combined myoinositol and folic acid supplementation. No case of NTDs was observed, despite the high recurrence risk in the mothers. Taken together, those data suggest that periconceptional folic acid plus myoinositol can reduce both the occurrence and recurrence risks of NTDs in a greater number of cases than folic acid alone.

Folate, homocysteine and selected vitamins and minerals status in infertile women

Objectives: Diet has been recognised as a crucial factor influencing fetal and maternal health. Adequate levels of substances such as homocysteine, folate and vitamin B12 have been associated with a higher rate of success in infertility treatments. Few data, however, are available on the average levels of micronutrients in the blood of reproductive-aged women, and specific values for adequate levels are not available. The aim of this cross-sectional study was to measure levels of folate, homocysteine and selected vitamins and minerals in women attending the infertility unit of an academic hospital for in vitro fertilisation (IVF).Methods: Fasting venous blood samples were taken in the morning during routine screening before IVF in order to measure: serum folate, red blood cell (RBC) folate, total plasma homocysteine, vitamin B12, vitamin A, vitamin E, serum iron and serum ferritin.Results: Among 269 women aged 37 ± 4 years, only 69% and 44% showed adequate levels of homocysteine and vitamin B12, respectively. Serum folate was appropriate in 78% of the study participants, but only a minority (12%) had a concentration of RBC folate regarded as optimal for the prevention of fetal neural tube defects. Serum levels of vitamin A, vitamin E, iron and ferritin were, however, appropriate in the vast majority of participants (>80%).Conclusion: Folate levels were largely inadequate among women attending an infertility clinic for IVF. Vitamin B12 levels were also found to be inadequate.

Hypermethylation of AKT2 gene is associated with neural-tube defects in fetus

IntroductionNeural-tube defects (NTDs) are common birth defects of complex etiology. Although many studies have confirmed a genetic component, the exact mechanism between DNA methylation and NTDs remains unclear. MethodsIn this work, we investigated the alteration of methylation from placental tissues obtained from 152 normal infants or with NTDs in 130 children with neural-tube defects. Genome-wide changes in DNA methylation were measured using the NimbleGen microarray. The expression levels of 12 genes were also determined, and two genes (AKT2 and CDC25C) showed low expression in NTDs by quantitative real-time PCR analysis. Then, the methyhlated region of AKT2 promoter sequences were confirmed by massARRAY. ResultsA total of 150 differentially methylated regions (81 low methylated regions and 69 high methylated regions) were selected by microarray. The expression levels of AKT2 and CDC25C showed lower expression in NTDs. And the percentage of methyhlated region of AKT2 promoter were increased in NTDs. ConclusionsDNA mythelation was one of the possible epigenetic variations correlated with the occurrence of NTDs, and AKT2 may be a candidate gene for NTDs.

Cadmium-induced neural tube defects and fetal growth restriction: Association with disturbance of placental folate transport

Previous studies found that maternal Cd exposure on gestational day (GD)9 caused forelimb ectrodactyly and tail deformity, the characteristic malformations. The aim of the present study was to investigate whether maternal Cd exposure on GD8 induces fetal neural tube defects (NTDs). Pregnant mice were intraperitoneally injected with CdCl2 (2.5 or 5.0mg/kg) on GD8. Neither forelimb ectrodactyly nor tail deformity was observed in mice injected with CdCl2 on GD8. Instead, maternal Cd exposure on GD8 resulted in the incidence of NTDs. Moreover, maternal Cd exposure on GD8 resulted in fetal growth restriction. In addition, maternal Cd exposure on GD8 reduced placental weight and diameter. The internal space of maternal and fetal blood vessels in the labyrinth layer was decreased in the placentas of mice treated with CdCl2. Additional experiment showed that placental PCFT protein and mRNA, a critical folate transporter, was persistently decreased when dams were injected with CdCl2 on GD8. Correspondingly, embryonic folate content was markedly decreased in mice injected with CdCl2 on GD8, whereas Cd had little effect on folate content in maternal serum. Taken together, these results suggest that maternal Cd exposure during organogenesis disturbs transport of folate from maternal circulation to the fetuses through down-regulating placental folate transporters.

Maternal 25-hydroxyvitamin D level and the occurrence of neural tube defects in Tunisia

ObjectiveTo determine whether low vitamin D levels in pregnant women are associated with the occurrence of neural tube defects (NTDs) in Tunisia. MethodsIn a prospective study, pregnant women were recruited at a center in Tunis between January 1, 2012, and December 30, 2013. Women carrying a fetus with a severe NTD were recruited before elective termination. Matched, healthy pregnancy women were enrolled into a control group. Plasma levels of 25-hydroxyvitamin D were measured by a competitive chemiluminescence immunoassay. ResultsOverall, 68 women formed the NTD group and 64 the control group. The mean maternal vitamin D level was significantly lower in the NTD group (20.65±10.25nmol/L) than in the control group (28.30±13.82nmol/L; P<0.001). Vitamin D deficiency was recorded for 53 (78%) women in the NTD group and 39 (61%) in the control group. Vitamin D insufficiency was recorded for 15 (22%) women in the NTD group and 20 (31%) in the control group. Vitamin D sufficiency was found only in the control group (n=5 [8%]; P<0.001). ConclusionThe findings confirm an association between a decreased vitamin D level in pregnant women and the risk of fetal NTDs.

Identification of Biomarkers by Proteomics for Prenatal Screening for Neural Tube Defects

Neural tube defect (NTD) is a serious congenital defect, but current methods for identifying NTD are limited. We used proteomic analysis of maternal serum to identify NTD-specific proteins whose levels differed between women with NTD fetuses (n = 50) and those with healthy fetuses (n = 40). Three NTD-specific protein peaks (8,130.6, 15,941.7, and 3,960.3 m/z) were identified using MALDI-TOF-mass spectrophotemetry, and were included in a diagnostic model developed using Biomarker Patterns software. The model used cut-offs for the relative intensity of the three peaks to indicate if a case had or did not have NTD. The model identified 48 of the 50 NTD cases and 36 of the 40 control cases correctly, resulting in the sensitivity of 96.0% (48/50) and the specificity of 90.0% (36/40). The diagnostic model was also tested on 105 clinical cases at high risk for NTD, as determined by having high alpha-fetoprotein levels, resulting in the sensitivity of 100% (101/101) and the specificity of 75.0% (3/4). Using the International Protein Index database, we identified proteins with a molecular mass of 8,130.6 Da as ADP-ribosylation factor 1 and a protein similar to cold agglutinin FS-1 antibody light-chain. The 15,941.7-Da peak corresponded to vitamin K3 protein, and the identity of the 3,960.3-Da protein was unclear. Thus, this study developed a diagnostic model consisting of the three peaks which may be indicators of NTD. This new assay may be at least as accurate for diagnosing NTD compared with the commonly used clinical test that assesses alpha-fetoprotein levels.

Evaluation of maternal serum folate, vitamin B12, and homocysteine levels andfactor V Leiden, factor II g.20210G>A, and MTHFR variations in prenatallydiagnosed neural tube defects.

Neural tube defects (NTDs) are common congenital malformations that develop as a result of interactions between several genes and environmental factors. Many factors have been investigated in order to understand the etiology of NTDs, and many studies have identified folate intake as a common contributing factor. The exact etiology of the disease is still unknown. In this study, we compared serum folate, vitamin B12, and homocysteine levels, along with common thrombophilia-related genetic variations, including factor V Leiden, factor II g.20210G>A, MTHFR c.677C>T, and MTHFR c.1298A>C, in 35 pregnant women with fetal NTDs and 38 pregnant women with healthy fetuses. A significant difference in serum vitamin B12 level and factor V Leiden frequency was detected between the two groups. On the other hand, serum folate, homocysteine levels, and factor II g.20210G>A, MTHFR c.677C>T, and MTHFR c.1298A>C were not significantly different in the NTD group compared to the controls. These results indicate that vitamin B12 supplementation along with folate may help in lowering NTD frequency. In addition, this is the first study that provides evidence for a possible relationship between increased NTD risk and factor V Leiden.

Spina bifida in fetus is associated with an altered pattern of DNA methylation in placenta.

Failure in closure of neural tube leads to neural tube defects (NTDs), which are among the most common symptoms of human birth defects. Although epigenetic status in placenta is linked to fetal development, the mechanism behind this remains unknown. Because of the importance of DNA methylation in gene function, we set to explore whether or not DNA methylation in human placenta is also linked to fetal NTDs. Here we show for the first time that alteration of DNA methylation in placenta is closely associated with the phenotypes of fetal spina bifida (Sb). We found that patterns of DNA methylation for genes in neurological system process were differentially altered in the Sb placenta. In particular, the transcription regulatory regions of TRIM26 and GANS were kept at the hypomethylation status in Sb placenta alone. Accordingly, the protein levels of TRIM26 and GNAS were significantly elevated only in the Sb placenta but not in the Sb-affected fetuses. In cellular model of CHO cells deficient in Dihydrofolate reductase and treated with 5-aza-2'-deoxycytidine, the protein levels of GNAS and TRIM26 were significantly higher than those in normal control cells. These findings suggested that epigenetic status of genes in placenta have profound impacts on the development of NTDs.

Tissue-Specific Methylation of Long Interspersed Nucleotide Element-1 of Homo Sapiens (L1Hs) During Human Embryogenesis and Roles in Neural Tube Defects.

Epigenetic regulation of long interspersed nucleotide element-1 (LINE-1) retrotransposition events plays crucial roles during early development. Previously we showed that LINE-1 hypomethylation in neuronal tissues is associated with pathogenesis of neural tube defect (NTD). Herein, we further evaluated LINE-1 Homo sapiens (L1Hs) methylation in tissues derived from three germ layers of stillborn NTD fetuses, to define patterns of tissue specific methylation and site-specific hypomethylation at CpG sites within an L1Hs promoter region. Stable, tissue-specific L1Hs methylation patterns throughout three germ layer lineages of the fetus, placenta, and maternal peripheral blood were observed. Samples from maternal peripheral blood exhibited the highest level of L1Hs methylation (64.95%) and that from placenta showed the lowest (26.82%). Between samples from NTDs and controls, decrease in L1Hs methylation was only significant in NTD-affected brain tissue at 7.35%, especially in females (8.98%). L1Hs hypomethylation in NTDs was also associated with a significant increase in expression level of an L1Hs-encoded transcript in females (r = -0.846, p = 0.004). This could be due to genomic DNA instability and alternation in chromatins accessibility resulted from abnormal L1Hs hypomethylation, as showed in this study with HCT-15 cells treated with methylation inhibitor 5-Aza.

Magnetic Resonance Imaging Evaluation of Fetal Neural Tube Defects

Spinal dysraphism occurs early in gestation because of an abnormality in the closure of the neural tube. Defects can be classified as open or closed lesions based on clinical and imaging features. Biochemical evaluation and ultrasound studies are used as screening tools for neural tube defects. Ultrasound alone can accurately diagnose most neural tube lesions. Magnetic resonance imaging has increasingly been used as an adjuvant study and is useful in the assessment of the degree of hindbrain herniation and evaluation of the fetal brain and spinal cord anatomy when ultrasound is limited. This additional information can be useful in counseling, helping to determine if fetal surgery is an option as well as helping to plan delivery and postnatal management.

Folic acid in pregnancy and mortality from cancer and cardiovascular disease: further follow-up of the Aberdeen folic acid supplementation trial

BackgroundSupplemental periconceptional folic acid is recommended to reduce the risk of fetal neural tube defects. A previous report indicated an elevated risk of breast cancer and all cancer deaths in...

The outcome and course of pregnancies complicated with fetal neural tube defects

The objectives of this study were as follows: to present the course and outcome of pregnancies complicated with neural tube defects, determine the association between prenatal ultrasound diagnoses, and definitive diagnoses after autopsy.The survey was designed as a retrospective study and included 24 pregnant women who were attending a regular ultrasound examinations at the Department of Gynecology and Obstetrics, Clinical Center of Serbia, or patients who were referred from other institutions in Serbia.Neural tube defects are divided into five subgroups: spina bifida, meningocele, myelomeningocele, acranius, and anencephaly. The most frequent in the present study was spina bifida with 67%. All pregnancies complicated with neural tube defects were terminated.Their clinical severity and uncertain cause make them priorities for further research, whether to better target primary preventive measures, to improve in-utero surgery for prenatal repair, or to identify the causative genes to provide an objective basis for individual genetic counselling.

Levels of PAH–DNA adducts in cord blood and cord tissue and the risk of fetal neural tube defects in a Chinese population

IntroductionMaternal exposure to polycyclic aromatic hydrocarbons (PAHs) has been shown to be associated with an elevated risk for neural tube defects (NTDs). In the human body, PAHs are bioactivated and the resultant reactive epoxides can covalently bind to DNA to form PAH–DNA adducts, which may, in turn, cause transcription errors, changes in gene expression or altered patterns of apoptosis. During critical developmental phases, these changes can result in abnormal morphogenesis. ObjectivesWe aimed to examine the relationship between the levels of PAH–DNA adducts in cord blood and cord tissue and the risk of NTDs. MethodsFrom 2010 to 2012, 60 NTD cases and 60 healthy controls were recruited from a population-based birth defects surveillance system in five counties of Shanxi Province in Northern China, where the emission of PAHs remains one of the highest in the country and PAHs exposure is highly prevalent. PAH–DNA adducts in cord blood of 15 NTD cases and 15 control infants, and in cord tissue of 60 NTD cases and 60 control infants were measured using the 32P-postlabeling method. ResultsPAH–DNA adduct levels in cord blood tend to be higher in the NTD group (28.5 per 108 nucleotides) compared with controls (19.7 per 108 nucleotides), although the difference was not statistically significant (P=0.377). PAH–DNA adducts in cord tissue were significantly higher in the NTD group (24.6 per 106 nucleotides) than in the control group (15.3 per 106 nucleotides), P=0.010. A positive dose-response relationship was found between levels of PAH–DNA adducts in cord tissue and the risk of NTDs (P=0.009). When the lowest tertile was used as the referent and potential confounding factors were adjusted for, a 1.03-fold (95% CI, 0.37–2.89) and 2.96-fold (95% CI, 1.16–7.58) increase in the risk of NTDs was observed for fetuses whose cord tissue PAH–DNA adduct levels were in the second and highest tertile, respectively. ConclusionsHigh levels of PAH–DNA adducts in fetal tissues were associated with increased risks of NTDs.

Partial or complete coverage of experimental spina bifida by simple intra-amniotic injection of concentrated amniotic mesenchymal stem cells

PurposeWe sought to determine whether simple intra-amniotic delivery of concentrated amniotic mesenchymal stem cells (afMSCs) may elicit prenatal coverage of experimental spina bifida. MethodsTime-dated pregnant Sprague–Dawley dams (n=24) exposed to retinoic acid for the induction of fetal neural tube defects were divided in three groups. Group I had no further manipulations. Groups II and III received volume-matched intra-amniotic injections of either saline (Group II) or a suspension of syngeneic afMSCs labeled with green fluorescent protein (Group III) in all fetuses (n=202) on gestational day 17 (term=21–22 days). Animals were killed before term. Statistical comparisons were by ANOVA (P<0.05). ResultsOf 165 fetuses viable at euthanasia, a spina bifida was present in 58% (96/165), with no significant differences in defect dimension across the groups (P=0.19). However, variable degrees of coverage of the defect by a rudimentary skin confirmed histologically were only present in Group III (P<0.001), in which donor afMSCs were documented, with no differences between Groups I and II (P=0.98). ConclusionsAmniotic mesenchymal stem cells can induce partial or complete coverage of experimental spina bifida after concentrated intra-amniotic injection. Trans-amniotic stem cell therapy (TRASCET) may become a practical option in the prenatal management of spina bifida.

RETIRED: Prenatal Screening, Diagnosis, and Pregnancy Management of Fetal Neural Tube Defects

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Folate deficiency-induced oxidative stress contributes to neuropathy in young and aged zebrafish — Implication in neural tube defects and Alzheimer's diseases

Folate is a nutrient essential for the development, function and regeneration of nervous systems. Folate deficiency has been linked to many neurological disorders including neural tube defects in fetus and Alzheimer's diseases in the elderly. However, the etiology underlying these folate deficiency-associated diseases is not completely understood. In this study, zebrafish transgenic lines with timing and duration-controllable folate deficiency were developed by ectopically overexpressing a recombinant EGFP-γ-glutamyl hydrolase (γGH). Impeded neural crest cell migration was observed in the transgenic embryos when folate deficiency was induced in early stages, leading to defective neural tube closure and hematopoiesis. Adding reduced folate or N-acetylcysteine reversed the phenotypic anomalies, supporting the causal link between the increased oxidative stress and the folate deficiency-induced abnormalities. When folate deficiency was induced in aged fish accumulation of beta-amyloid and phosphorylated Tau protein were found in the fish brain cryo-sections. Increased autophagy and accumulation of acidic autolysosome were apparent in folate deficient neuroblastoma cells, which were reversed by reduced folate or N-acetylcysteine supplementation. Decreased expression of cathepsin B, a lysosomal protease, was also observed in cells and tissue with folate deficiency. We concluded that folate deficiency-induced oxidative stress contributed to the folate deficiency-associated neuropathogenesis in both early and late stages of life.

Organochlorine pesticide levels in maternal serum and risk of neural tube defects in offspring in Shanxi Province, China: A case–control study

Organochlorine pesticides (OCPs) in placental tissue have been reported to be associated with an increased risk for fetal neural tube defects (NTDs). Our case–control study was performed to explore the association between maternal serum OCP concentration and NTD risk in offspring. Serum samples were collected from 117 mothers who delivered NTD infants (case group) and 121 mothers who delivered healthy infants (control group). Only three of the 25 OCPs were detected in more than half of the maternal serum samples. The median concentration of total OCPs in the case group was significantly higher than that of the control group. However, no dose–response relationships between higher levels of any individual OCPs or total OCPs and the risk of NTDs or subtypes were observed in either the unadjusted binary unconditional logistic regression model or the model adjusted by potential confounders. We conclude that no clear association between maternal serum OCP residues and NTD risk in offspring was observed in this population. CapsuleNo clear association between maternal serum levels of organochlorine pesticides and risk of neural tube defects in offspring was observed for a Chinese population.