Insufficient folic acid intake in the Netherlands: what about the future?

BACKGROUND: In 1993 all women of childbearing age in the Netherlands were advised to take a daily 0.5 mg folic acid pill to reduce the risk for neural tube defects. This study describes both recent and past awareness and use of folic acid supplements in relation to socio-economic status in the Northern Netherlands. The consequences of a recent report of the Dutch Health Council report will be discussed as well. METHODS: In the most recent cross-sectional study (November 2000), pregnant women filled out a questionnaire. Out of 473 women, 461 were willing to cooperate. The highest fulfilled level of education was taken as an indicator for socio-economic status. RESULTS: Seventy-seven percent (n = 357) of the respondents had heard about folic acid before being pregnant. Sixty-three percent (n = 289) knew about the protective effect for NTDs and 33% (n = 151) knew the entire advised period. Sixty-one percent (n = 265) of the respondents used folic acid in some part of the advised period and 36% (n = 164) used it in the entire advised period. Higher educated women knew more about folic acid and used it significantly more often in the periconceptional period than lower educated women. CONCLUSIONS: Because compliance to proper use of folic acid was poor, food fortification in the Netherlands must be seriously considered. The Dutch Health Council wants to limit the fortification of food products to those products that are especially aimed for women who wish to become pregnant. The fortification of specific products instead of staple foods is a missed chance to reduce NTDs and possibly other birth defects and cardiovascular defects as well.     

Behavioral effects of prenatal folate deficiency in mice

BACKGROUND: Folate supplementation decreases the incidence of birth defects such as neural tube defects (NTDs). We and others have shown that gestational dietary folate deficiency that does not produce overt NTDs can alter fetal neural histology. Accordingly, murine offspring were examined for the possible functional consequences of prenatal folate deficiency. METHODS: CD-1 mice were fed a diet of chow containing 400, 600, or 1200 nmol of folic acid/kg of chow for eight weeks prior to breeding and until GD18, at which time all dams were placed on folate-replete chow. Behavioral tests of male and female offspring included righting reflex, negative geotaxis, forelimb hanging, motor coordination, open field activity, and elevated plus maze activity. RESULTS: Of greatest significance, the adult offspring that were prenatally folate-deficient exhibited more anxiety-related behavior in the elevated plus maze. Offspring of the 400 nmol of folic acid/kg of chow diet group exhibited significantly shorter durations in the open arms and longer durations in the closed arms. Further, these two behaviors were dose-related. There was also a trend for the prenatally folate-deficient adult mice to exhibit more thigmotaxis (wall-hugging) behavior in the open field, entering the central area less frequently than controls. There were few other differences in tested behaviors between folate-deficient and folate-replete mice. CONCLUSIONS: Prenatal folate deficiency that is repleted at birth can manifest later with increased anxiety 9-12 weeks after birth.     

Higher serum homocysteine and lower thyroid hormone levels in pregnant women are associated with neural tube defects

BackgroundThis study tested the hypothesis that abnormal maternal metabolism of both homocysteine and thyroid hormone network in pregnant women is associated with neural tube defects (NTDs) in a part of China with high NTD prevalence.MethodsA case–control study was performed between 2007 and 2009 in Lüliang Mountains, Shanxi Province. This study included 83 pregnant women who had fetuses with NTDs (cases) and 90 pregnant women with normal fetuses (controls). In addition, a cell model to illustrate the epidemiological findings was established.ResultsFetuses of mother who had both high total homocysteine (tHcy) and inadequate free thyroxine were 3 times more at risk of developing NTDs (adjusted odds ratio = 3.5; 95 % confidence interval = 1.2–10.4; cases vs. controls) using multivariate logistic regression models. Furthermore, biological interaction between metabolisms of Hcy and thyroid hormones was demonstrated in vitro. In homocysteine thiolactone of a metabolite of Hcy-treated mouse embryonic neural stem NE4C cells, genes (Bmp7, Ctnnb1, Notch 1, Gli2, and Rxra) related to both neural tube closure and thyroid hormone network were shown to be regulated by H3K79 homocysteinylation, which increased their expression levels.ConclusionsThe effect of maternal serum high tHcy on risk of developing NTDs is depended on maternal serum level of thyroxine. Meanwhile, a higher level of tHcy might also affect both maternal metabolism of thyroid hormone and neural tube closure in embryogenesis through homocysteinylation of histones.     

Serum zinc, selenium, copper, and lead levels in women with second-trimester induced abortion resulting from neural tube defects

Neural tube defects are important causes of infant mortality and childhood morbidity. We investigated the relationship between zinc, selenium, copper, and lead concentrations and neural-tube-defect occurrence in women with a second-trimester termination due to fetal-neural-tube defects (NTDs) in this case-control study. Fourteen pregnant women whose pregnancies were terminated as a result of second-trimester ultrasonographic diagnosis of neural tube defects were recruited as cases. The control group (n=14) consisted of women who were selected among age-, gravidity-, and socio-economic-state (SES)-matched women who had a normal triple-screen and targeted ultrasound during the second trimester with documented normal fetal outcome. Zinc and copper determinations were made using flame atomic absorption spectrophotometer (AAS). Graphite furnace AAS was used for Pb, and Se levels were measured with hydride generation AAS. Cases had significantly low serum zinc and selenium levels (62.48±15.9 vs 102.6±23.7 and 55.16±11.3 vs 77.4±5.5, respectively, p<0.001). Serum Cu and whole-blood Pb levels were significantly high when compared to controls. There was a negative correlation between serum zinc and selenium levels, and serum copper levels (r=−425 and −0.443, p<0.05). Our results are consistent with some previous reports. The etiology of NTDs cannot be explained with one strict etiologic mechanism. On the contrary, an interaction among environmental, genetic, and nutritional factors such as trace elements and vitamins would explain these anomalies. If folic acid supplementation is given, additional Zn supplementation should be considered for the further decrease in the recurrence and occurrence of NTDs.     

Simultaneous quantification of 11 pivotal metabolites in neural tube defects by HPLC-electrospray tandem mass spectrometry

One-carbon metabolism that involves folate metabolism and homocysteine metabolism plays a powerful role in embryonic development. Any impairment to this metabolism during the neurulation process would trigger the occurrence of neural tube defects (NTDs). The great importance of one-carbon metabolism necessitates the establishment of methodology to determine the relative compounds involved in the metabolic cycles. We have developed a sensitive method for measurement of 11 pivotal compounds by using high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS/MS) in sera of pregnant women. Use of an aqueous chromatography column increased retention time and separation of the polar compounds in the system, resulting in fewer co-elution and interference from the other compounds that can lead to ion suppression. Calibration curves suitable for the analysis of maternal serum were linear (r(2)>0.997) with limits of detection from 0.05 to 1ng/mL. Intra-day coefficients of variation (CVs) and inter-day CVs were both lower than 11%. With the developed method, 96 serum samples including 46 cases and 50 controls were analyzed. The established method provided a reliable method for quantifying most of the compounds involved in the one-carbon metabolism simultaneously, thus made it possible to elucidate NTDs with multiple factors instead of one single and provided a solid foundation for the diagnosis and prevention of NTDs as well as some other one-carbon metabolism related diseases.     

Prevention of NTDs with periconceptional multivitamin supplementation containing folic acid in China

BACKGROUND: Maternal nutritional factors seem to contribute substantially to the complex etiologies of NTDs. Foremost among these factors is the periconceptional use of supplementation containing folic acid, which is associated with a reduction in the risk of women having NTD‐affected pregnancies. This study was designed to observe the effectiveness of multivitamin supplementation containing folic acid in preventing NTDs in a Chinese population and to detect factors that would impact the effectiveness. METHODS: Through family planning networks, a population‐based community intervention study was carried out in 18 counties of China. Participants were divided into an intervention (taking multivitamin) group and a control group, and were followed up according to periconceptional multivitamin supplementation (in general 6 mg) for 2 years. Women who had a pregnancy were followed up from 28 weeks gestation at least to pregnancy termination, and the outcome was recorded. The incidence rate of the two groups and the relative risks were calculated to evaluate the efficacy of the multivitamin supplement in preventing NTDs. RESULTS: During 2000 and 2002, all of the women having pregnancies with birth defects and women whose pregnancies were without any birth defects were interviewed. Nine NTDs were recorded from 25,444 pregnancies (NTD birth prevalence = 0.35/1,000 pregnancies) in the intervention group and 48 NTDs among 26,599 pregnancies (NTD birth prevalence = 1.80/1,000 pregnancies) in the control group. The protective rate was 80.4%. CONCLUSIONS: Periconceptional multivitamin supplementation containing folic acid can prevent the occurrence of NTDs with the beneficial effect dependent on the frequency and timing of the supplementation. Our study suggests that multivitamin supplement containing folic acid taken from a time point of 2 months before conception and continuing until completion of the second month after conception and taken more than five times per week can significantly reduce the risks of NTDs. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.     

An embryoprotective role for glucose-6-phosphate dehydrogenase in developmental oxidative stress and chemical teratogenesis.

The primary recognized health risk from common deficiencies in glucose-6-phosphate dehydrogenase (G6PD), a cytoprotective enzyme for oxidative stress, is red blood cell hemolysis. Here we show that litters from untreated pregnant mutant mice with a hereditary G6PD deficiency had increased prenatal (fetal resorptions) and postnatal death. When treated with the anticonvulsant drug phenytoin, a human teratogen that is commonly used in pregnant women and causes embryonic oxidative stress, G6PD-deficient dams had higher embryonic DNA oxidation and more fetal death and birth defects. The reported G6PD gene mutation was confirmed and used to genotype fetal resorptions, which were primarily G6PD deficient. This is the first evidence that G6PD is a developmentally critical cytoprotective enzyme for both endogenous and xenobiotic-initiated embryopathic oxidative stress and DNA damage. G6PD deficiencies accordingly may have a broader biological relevance as important determinants of infertility, in utero and postnatal death, and teratogenesis.     

碱基切除修复基因Lig3对小鼠胚胎神经发育的影响

摘要 目的：DNA连接酶III（DNA ligase III, Lig3）基因是碱基切除修复通路中的关键基因,在胚胎发育过程中发挥重要作用,通过研究Lig3基因在叶酸代谢障碍状态下的表达情况,探讨其对小鼠胚胎神经发育的影响。方法：采用无特定病原体（specific pathogen free, SPF）级C57BL/6J成年小鼠（8-9周,18-20 g）,雌雄1:1合笼,孕鼠随机分为实验组和对照组,孕7.5天实验组腹腔注射4.5 mg/kg体重甲氨蝶呤（Methotrexate, MTX,二氢叶酸还原酶抑制剂）诱导产生叶酸代谢障碍的小鼠神经管畸形（neural tube defects, NTDs）模型,对照组腹腔注射等体积的生理盐水。孕10.5天体视显微镜下观察胎鼠的发育情况。同时利用200 nM的MTX建立叶酸代谢障碍的小鼠神经干细胞模型。在模型建立成功的基础上,应用实时荧光定量聚合酶链反应(Real time quantitative PCR,RT-qPCR)及免疫印迹（Western blot）等方法研究碱基切除修复通路相关基因Lig3的表达水平。结果：4.5 mg/kg 体重MTX处理孕鼠后胎鼠NTDs的发生率为31.1%（19/61）,而正常对照组未见胎鼠NTDs的发生。在体视显微镜下可见NTDs胎鼠神经管未闭合,而正常胎鼠发育完好。RT-qPCR检测发现叶酸代谢障碍小鼠NTDs 胚胎神经组织中Lig3 mRNA的表达水平明显低于对照组（P<0.05）。Western blot检测发现,与对照组相比,叶酸代谢障碍NTDs胎鼠神经组织中Lig3蛋白水平明显降低（P<0.05）。同时,在MTX处理的神经干细胞中,Lig3的表达水平明显低于对照组（P<0.05）。对凋亡相关蛋白Cleaved caspase-3进行检测发现MTX处理后的NTDs胎鼠神经组织及细胞模型中其表达均明显增加,表明细胞凋亡增加。结论：在叶酸代谢障碍前提下,Lig3表达降低,DNA修复功能减弱,细胞凋亡增加,导致NTDs的发生,为NTDs及出生缺陷的防控提供新思路。     

Inositol- and folate-resistant neural tube defects in mice lacking the epithelial-specific factor Grhl-3

The neural tube defects (NTDs) spina bifida and anencephaly are widely prevalent severe birth defects. The mouse mutant curly tail (ct/ct) has served as a model of NTDs for 50 years, even though the responsible genetic defect remained unrecognized. Here we show by gene targeting, mapping and genetic complementation studies that a mouse homolog of the Drosophila grainyhead (grh) gene, grainyhead-like-3 (Grhl3), is a compelling candidate for the gene underlying the curly tail phenotype. The NTDs in Grhl3-null mice are more severe than those in the curly tail strain, as the Grhl3 alleles in ct/ct mice are hypomorphic. Spina bifida in ct/ct mice is folate resistant, but its incidence can be markedly reduced by maternal inositol supplementation periconceptually. The NTDs in Grhl3-/- embryos are also folate resistant, but unlike those in ct/ct mice, they are resistant to inositol. These findings suggest that residual Grhl3 expression in ct/ct mice may be required for inositol rescue of folate-resistant NTDs.     

Etiologic heterogeneity of neural tube defects. II. Clues from family studies.

We previously reported that among neural tube defects (NTDs) with no known causes the ones that occur alone (singles) have different epidemiologic characteristics from those that occur in combination with other defects (multiples), suggesting an underlying causal heterogeneity. In this study, we compared family histories of 223 single NTD cases and 66 multiple cases ascertained through the Metropolitan Atlanta Congenital Defects Program (MACDP) between 1970 and 1979. Compared with siblings of multiples, siblings of singles had a higher precurrence rate for NTDs (2.0% vs. 0.0%) and for birth defects in general (10.9% vs. 3.0%). Furthermore, siblings of singles that were born within 2 years before the birth of the index case had a higher precurrence rate for NTDs (8.0% vs. 1.1%) and for major birth defects (20.0% vs. 2.9%) than had those born earlier. These results further suggest that NTDs are etiologically heterogeneous, depending on the presence of associated defects, and point to important environmental influences in the increased risk for birth defects among siblings of singles. Larger studies are needed to confirm these data and show that single and multiple NTDs have different recurrence rates, not only for NTDs but also for other birth defects.     

MTX诱导神经管畸形动物模型的建立

目的:通过二氢叶酸还原酶(DHFR)竞争性抑制剂甲氨蝶呤(MTX)建立叶酸缺乏的神经管畸形(NTDs)动物模型。方法:本研究用孕7.5天C57BL/6J小鼠,采用腹腔注射(ip)不同剂量的MTX建立叶酸代谢障碍的小鼠NTDs模型,LC/MS/MS及酶学方法检测胚胎组织中叶酸相关代谢产物水平及DHFR活性。结果:最佳的致畸剂量为,MTX 4.5 mg/kg,其NTDs发生率最高为31.4%。畸形的胎鼠表型多数为后脑泡未闭,且其身长(4.21±0.76),体重(9.49±3.48)均明显低于对照组(6.32±0.56;22.76±3.23)(P0.05;P0.05)。MTX实验组的胚胎组织中DHFR的活性较对照组显著降低(P0.05),5-MeTHF和5-FoTHF的浓度和对照组相比也明显降低(P0.05)。结论:本研究成功的建立了叶酸缺乏的神经管畸形动物模型。     

同型半胱氨酸与神经管畸形的相关病因学研究进展

神经管畸形(neural tube defects,NTDs)是一种最常见的严重中枢神经系统先天性畸形,在世界各地均有发生。它是造成流产、死产的主要原因之一,即便胎儿存活,也严重影响患儿的生长发育和生活质量,同时给家庭和社会带来沉重的精神压力和经济负担。神经管畸形的发生绝大多数是由遗传因素与环境因素相互作用的结果,若孕妇在孕早期缺乏叶酸、高热、接触射线、服用药物、感染或发生妊娠期糖尿病等条件下,结合遗传因素作用,均有可能导致神经管畸形的发生,但其目前其的确切病因及其发病机制仍有待深入研究。大量研究表明,在孕妇血清中低叶酸、低维生素B12水平及高血浆同型半胱氨酸(Hcy)水平,都与NTDs的发生密切相关。本文主要围绕同型半胱氨酸的代谢,从分子水平和基因水平对与神经管畸形相关的各因素做一综述。     

Analyses of copy number variation reveal putative susceptibility loci in MTX‐induced mouse neural tube defects

Copy number variations (CNVs) are thought to act as an important genetic mechanism underlying phenotypic heterogeneity. Impaired folate metabolism can result in neural tube defects (NTDs). However, the precise nature of the relationship between low folate status and NTDs remains unclear. Using an array‐comparative genomic hybridization (aCGH) assay, we investigated whether CNVs could be detected in the NTD embryonic neural tissues of methotrexate (MTX)‐induced folate dysmetabolism pregnant C57BL/6 mice and confirmed the findings with quantitative real‐time PCR (qPCR). The CNVs were then comprehensively investigated using bioinformatics methods to prioritize candidate genes. We measured dihydrofolate reductase (DHFR) activity and concentrations of folate and relevant metabolites in maternal serum using enzymologic method and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Three high confidence CNVs on XqA1.1, XqA1.1‐qA2, and XqE3 were found in the NTD embryonic neural tissues. Twelve putative genes and three microRNAs were identified as potential susceptibility candidates in MTX‐induced NTDs and possible roles in NTD pathogenesis. DHFR activity and 5‐methyltetrahydrofolate (5‐MeTHF), 5‐formyltetrahydrofolate (5‐FoTHF), and S‐adenosylmethionine (SAM) concentrations of maternal serum decreased significantly after MTX injection. These findings suggest that CNVs caused by defects in folate metabolism lead to NTD, and further support the hypothesis that folate dysmetabolism is a direct cause for CNVs in MTX‐induced NTDs. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 74: 877–893, 2014     

Recommendations on the use of folic acid supplementation to prevent the recurrence of neural tube defects. Clinical Teratology Committee,Canadian College of Medical Geneticists.

OBJECTIVE: To prevent the recurrence of neural tube defects (NTDs) in families at increased risk of having offspring with NTDs with the use of periconceptional folic acid supplementation. OPTIONS: Genetic counselling and prenatal diagnosis of NTDs. OUTCOMES: NTDs cause stillbirth, neonatal death and severe disabilities. The cost for medical care and rehabilitation in the first 10 years of life of a child with spina bifida cystica was estimated to be $42,507 in 1987. EVIDENCE: The authors reviewed the medical literature, communicated with investigators from key studies, reviewed policy recommendations from other organizations and drew on their own expertise. A recent multicentre randomized controlled trial showed that among women at high risk of having a child with an NTD those who received 4 mg/d of folic acid had 72% fewer cases of NTD-affected offspring than nonsupplemented women. Two previous intervention studies also demonstrated that folic acid supplementation was effective in reducing the rate of NTD recurrence. Several retrospective studies support this conclusion. VALUES: Recommendations are the consensus of the Clinical Teratology Committee of the Canadian College of Medical Geneticists (CCMG) and have been approved by the CCMG Board. The committee believes that primary prevention of NTDs is preferable to treatment or to prenatal detection and abortion. BENEFITS, HARMS AND COSTS: Folic acid supplementation should result in fewer NTDs among infants in Canada and ancillary savings in medical costs. The recommended dosage of folic acid is not known to be associated with adverse effects. Higher dosages of folic acid may make vitamin B12 deficiency difficult to diagnose and may alter seizure frequency in patients with epilepsy due to drug interactions with anticonvulsants. RECOMMENDATIONS: A minimum dosage of folic acid of 0.8 mg/d, not to exceed 5.0 mg/d, is recommended along with a well-balanced, nutritious diet for all women who are at increased risk of having offspring with NTDs and who are planning a pregnancy or may become pregnant. Supplementation should begin before conception and continue for at least 10 to 12 weeks of pregnancy. VALIDATION: These guidelines are similar to those of the Society of Obstetricians and Gynaecologists of Canada, the US Centers for Disease Control and Prevention and the Department of Health in Britain. SPONSORS: These guidelines were developed by the CCMG Clinical Teratology Committee and endorsed by the Board of the CCMG. No funding for the development of these guidelines was obtained from any other sources.     

Effects of inositol supplementation in a cohort of mothers at risk of producing an NTD pregnancy

Neural tube defects (NTDs), most commonly spina bifida and anencephaly, can be prevented with periconceptional intake of folic acid in about 70% of cases. Recurrence of NTDs despite supplementation of high dose of folic acid further suggests that a proportion of NTD cases might be resistant to folic acid. Moreover, heterogeneity of NTDs has been suggested in animal studies, indicating that only some sub-type of NTDs should be considered sensitive to folate intake. Inositol isomers (particularly myo- and chiro-inositol) can prevent folate-resistant NTDs in the curly-tail mutant mouse, suggesting that some cases of human NTDs might benefit from inositol supplementation. In humans, lower inositol blood concentration was found in pregnant women carrying NTD fetuses, whereas a periconceptional combination therapy with folic acid associated with inositol has been linked to normal live births, despite high NTD recurrence risk. Fifteen pregnancies from 12 Caucasian women from different parts of Italy with at least one previous NTD-affected pregnancy underwent periconceptional combined myo-inositol and folic acid supplementation. Maternal serum α-feto-protein levels were found in the normal range, and normal results on ultrasound examination were found in all the pregnancies that followed. No collateral effects or intense uterine contractions were demonstrated in this pilot study in any of the pregnancies after inositol supplementation, and seventeen babies were born without any type of NTD.     

Sex difference in neural tube defects in p53-null mice is caused by differences in the complement of X not Y genes

To shed light on the biological origins of sex differences in neural tube defects (NTDs), we examined Trp53-null C57BL/6 mouse embryos and neonates at 10.5 and 18.5 days post coitus (dpc) and at birth. We confirmed that female embryos show more NTDs than males. We also examined mice in which the testis-determining gene Sry is deleted from the Y chromosome but inserted onto an autosome as a transgene, producing XX and XY gonadal females and XX and XY gonadal males. At birth, Trp53 nullizygous mice were predominantly XY rather than XX, irrespective of gonadal type, showing that the sex difference in the lethal effect of Trp53 nullizygosity by postnatal day 1 is caused by differences in sex chromosome complement. At 10.5 dpc, the incidence of NTDs in Trp53-null progeny of XY* mice, among which the number of the X chromosomes varies independently of the presence or absence of a Y chromosome, was higher in mice with two copies of the X chromosome than in mice with a single copy. The presence of a Y chromosome had no protective effect, suggesting that sex differences in NTDs are caused by sex differences in the number of X chromosomes.     

Plasma vitamin values and antiepileptic therapy: case reports of pregnancy outcomes affected by a neural tube defect

BACKGROUND: Folic acid supplementation reduces the occurrence of neural tube defects (NTDs); however, it is not clear whether it protects against teratogenic effects of antiepileptic drugs. METHODS: We report the cases of four pregnant women receiving valproic acid therapy, who all had NTD-affected offspring, despite periconceptional 5 mg/day of folic acid supplementation (cases), and investigated homocysteine metabolism, linked with folate metabolism. Their plasma homocysteine, folates, and vitamin B6 and B12 results were compared with values of two other women, who were also receiving valproic acid and folic acid complement, but who had normal pregnancies (valproic acid controls), and values of 40 pregnant women who had normal pregnancies and were not receiving any therapy (controls without therapy). Because of the possible existence of a genetic susceptibility, polymorphisms in homocysteine metabolism were sought. RESULTS: Two cases showed a decreased phosphopyridoxal level, compared with levels in the controls not receiving therapy. The genotype TT (C677T) is an NTD genetic susceptibility, but it was observed in only one valproic acid control. Various polymorphisms were observed in the cases, but were also common in the controls. Several studies have reported that valproic acid therapy lowers vitamin B6 levels. Our case with the greatest decrease in plasma phosphopyridoxal, who was taking periconceptional folic acid plus pyridoxine therapy, had a normal second pregnancy outcome. CONCLUSIONS: In addition to folates, other vitamins, such as vitamin B6, may have played a role in NTDs in our patients taking an antiepileptic drug.     

Metabolomic evaluation of di-n-butyl phthalate-induced teratogenesis in mice

Di-n-butyl phthalate (DBP) has been linked to the neural, reproductive and developmental toxicity. We present here a metabolomic study that characterized the metabolic variations associated with the DBP-induced teratogenesis in maternal and fetal mice. DBP at 50 and 300?mg/kg were administrated to pregnant C57 mice, via gastric intubation on gestation day 7?C9, respectively. Maternal mice were euthanized on gestation day 16 and examined for fetal development and malformations. Metabolomic study of maternal serum, placenta and fetal brain tissues was performed using gas chromatography time-of-flight mass spectrometry combined with multivariate data analysis (MVDA). The results showed that a 50?mg/kg dose of DBP had no significant effect on fetal development and a 300?mg/kg dose caused embryo resorption and fetal malformations (primarily eye abnormalities and encephalocele). MVDA indicated that DBP at two doses gave rise to disruption of maternal and fetal metabolic profiles characterized by significantly altered tricarboxylic acid cycle, amino acid, purine and lipid metabolism.     

Neural tube defects and maternal biomarkers of folate, homocysteine, and glutathione metabolism

BACKGROUND: Alterations in maternal folate and homocysteine metabolism are associated with neural tube defects (NTDs). The role played by specific micronutrients and metabolites in the causal pathway leading to NTDs is not fully understood. METHODS: We conducted a case-control study to investigate the association between NTDs and maternal alterations in plasma micronutrients and metabolites in two metabolic pathways: methionine remethylation and glutathione transsulfuration. Biomarkers were measured in a population-based sample of women who had NTD-affected pregnancies (n = 43) and a control group of women who had a pregnancy unaffected by a birth defect (n = 160). We compared plasma concentrations of folate, vitamin B(12), vitamin B(6), methionine, S-adenosylmethionine (SAM), s-adenosylhomocysteine (SAH), adenosine, homocysteine, cysteine, and reduced and oxidized glutathione between cases and controls after adjusting for lifestyle and sociodemographic factors. RESULTS: Women with NTD-affected pregnancies had significantly higher plasma concentrations of SAH (29.12 vs. 23.13 nmol/liter, P = .0011), adenosine (0.323 vs. 0.255 mumol/liter; P = .0269), homocysteine (9.40 vs. 7.56 micromol/liter; P < .001), and oxidized glutathione (0.379 vs. 0.262 micromol/liter; P = .0001), but lower plasma SAM concentrations (78.99 vs. 83.16 nmol/liter; P = .0172) than controls. This metabolic profile is consistent with reduced methylation capacity and increased oxidative stress in women with affected pregnancies. CONCLUSIONS: Increased maternal oxidative stress and decreased methylation capacity may contribute to the occurrence of NTDs. Further analysis of relevant genetic and environmental factors is required to define the basis for these observed alterations.