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PubMed2004

[Advances in the study of the etiologic relationship between reduced folate carrier gene (RFC1) and neural tube and craniofacial defects].

Neural tube and craniofacial defects are common birth defects which are ascribed to the combination of genetic and environmental factors. The population epidemiological studies suggested that periconceptional use of multivitamins containing folic acid can reduce a woman's risk of having a child with neural tube and craniofacial defects. It's a major environmental factor that periconceptional women with deficiency of folic acid may increase their risk for delivering babies with neural tube and craniofacial defects, but the mechanism by which folic acid facilitates this risk reduction is unknown. This paper reviews folate transport carrier, Reduced Folate Carrier (RFC)'s characteristics in biological chemistry, physiological function, the folate transport mechanism, structure, function, regulation and expression of reduced folate carrier gene (RFC1), and the relationship between RFC1 with plasm or erythrocyte folate level and neural tube defects, et al. It is suggested a etiologic hypothesis in investigation of candidate gene encoding specific folate-related pathways of neural tube and craniofacial defects.

Carrier Proteins↗
PubMed2000

[Preventing neural tube defects with periconceptional folic acid supplementation: a population-based intervention program in the China].

OBJECTIVES: To evaluate the effectiveness of periconceptional use of 400 microgram folic acid only on the prevention of neural tube defects (NTDs). METHOD: As part of a public health campaign in areas of high (North) and low (South) NTDs prevalence in the China during 1993 and 1995, 130 142 pill takers and 117 689 non-pill takers were recruited. Women were asked to begin taking a pill containing only 400 microgram of folic acid daily from the time of their premarital examination until the end of the first trimester of pregnancy. The outcomes of these pregnancies were ascertained through 1996. RESULTS: We identified 102 NTDs among offspring of pill takers and 173 NTDs among offspring of non-pill takers. The NTDs rate in offspring of non-pill takers was 4.8 per thousand (16/3 318) and 1.0 per thousand (28/28 625) in the south; while the rate in pill takers was 1.0 per thousand (13/13 012) in the north and 0.6 per thousand in the south. The greatest reduction in risk occurred among the fetuses or infants of a subgroup of women in the northern region with periconceptional use who took pills more than 80 percent of the time (reduction in risk, 85 percent as compared with the fetuses or infants of women who registered before their last menstrual period and who took no folic acid; 95 percent confidence interval, 62 to 94 percent). In the southern region the reduction in risk among the fetuses or infants of women with periconceptional use of folic acid was also significant (reduction in risk, 41 percent; 95% confidence interval, 3 to 64 percent). CONCLUSION: Periconceptional intake of supplements containing only 400 microgram folic acid can reduce the risk for NTDs in areas of high and low NTDs prevalence.

Adult↗
PubMed1999

Folic acid for the prevention of neural tube defects. American Academy of Pediatrics. Committee on Genetics.

The American Academy of Pediatrics endorses the US Public Health Service (USPHS) recommendation that all women capable of becoming pregnant consume 400 microgram of folic acid daily to prevent neural tube defects (NTDs). Studies have demonstrated that periconceptional folic acid supplementation can prevent 50% or more of NTDs such as spina bifida and anencephaly. For women who have previously had an NTD-affected pregnancy, the Centers for Disease Control and Prevention (CDC) recommends increasing the intake of folic acid to 4000 microgram per day beginning at least 1 month before conception and continuing through the first trimester. Implementation of these recommendations is essential for the primary prevention of these serious and disabling birth defects. Because fewer than 1 in 3 women consume the amount of folic acid recommended by the USPHS, the Academy notes that the prevention of NTDs depends on an urgent and effective campaign to close this prevention gap.

Dietary Supplements↗
PubMed1999

Embryonic lethality and defective neural tube closure in mice lacking squalene synthase.

Squalene synthase (SS) catalyzes the reductive head-to-head condensation of two molecules of farnesyl diphosphate to form squalene, the first specific intermediate in the cholesterol biosynthetic pathway. We used gene targeting to knock out the mouse SS gene. The mice heterozygous for the mutation (SS+/-) were apparently normal. SS+/- mice showed 60% reduction in the hepatic mRNA levels of SS compared with SS+/+ mice. Consistently, the SS enzymatic activities were reduced by 50% in the liver and testis. Nevertheless, the hepatic cholesterol synthesis was not different between SS+/- and SS+/+ mice, and plasma lipoprotein profiles were not different irrespective of the presence of the low density lipoprotein receptor, indicating that SS is not a rate-limiting enzyme in the cholesterol biosynthetic pathway. The mice homozygous for the disrupted SS gene (SS-/-) were embryonic lethal around midgestation. E9.5-10.5 SS-/- embryos exhibited severe growth retardation and defective neural tube closure. The lethal phenotype was not rescued by supplementing the dams either with dietary squalene or cholesterol. We speculate that cholesterol is required for the development, particularly of the nervous system, and that the chorioallantoic circulatory system is not mature enough to supply the rapidly growing embryos with maternal cholesterol at this developmental stage.

Animals↗
PubMed1976

Vitamin deficiencies and neural tube defects.

Serum folate, red cell folate, white blood cell vitamin C, riboflavin saturation index, and serum vitamin A were determined during the first trimester of pregnancy in over 900 cases. For each of these there was a social classes I + II showed the highest levels which differed significantly from other classes, except for serum folate. In 6 mothers who gave birth to infants with neural tube defects, first trimester serum folate, red cell folate, white blood cell vitamin C, and riboflavin values were lower than in controls. In spite of small numbers the differences were significant for red cell folate (P less than 0-001) and white blood cell vitamin C (P less than 0-05). These findings are compatible with the hypothesis that nutritional deficiencies are significant in the causation of congenital defects of the neural tube in man.

Adult↗
PubMed2001

Folic acid and prevention of neural tube defects in 2000 improved awareness--low peri-conceptional uptake.

Eight years have passed since recommendations were made by the Irish Department of Health on the importance of folic acid in the prevention of neural tube defects (NTD). There is currently no mandatory fortification of foodstuffs with folic acid in Ireland, with reliance placed on campaigns promoting increased dietary folate intake and supplements. We assessed knowledge and use of folic acid among 300 women attending ante-natal clinics in Dublin maternity hospitals in the year 2000 using an interviewer administered questionnaire. Qualitative information was obtained through means of a focus group. Ninety two percent of respondents had heard of folic acid and 67% knew it could prevent NTD. Thirty per cent were advised to take it peri-conceptionally but overall only 18% did so; 39% of women had planned their pregnancy. The focus group indicated that folic acid was not 'visible' enough and that fortification of food was more realistic. This study shows that improved folic acid awareness has not been accompanied by corresponding peri-conceptional uptake in 2000. Folic acid promotional campaigns should be continuous and targeted. Mandatory food fortification should be strongly considered.

Adult↗
PubMed1995

Low levels of selenium in mothers and their newborns in pregnancies with a neural tube defect.

OBJECTIVE: Very few data are presented in the literature about selenium (Se) in human fetal development. The aim of this paper was to study the relationship between maternal and neonatal Se status and neural tube defects (NTDs). PATIENTS AND METHODS: Serum and hair samples were obtained from 20 nonpregnant women, 32 healthy mothers with normal newborns, and 28 mothers who had a newborn with NTD, and their newborns at delivery. Serum Se levels, as ng/mL, and hair Se levels, as microgram/g, were determined on a Perkin-Elmer 1000 spectrophotometer (United Kingdom) by fluorometry. RESULTS: The mean maternal serum and hair Se concentrations in the NTD group (42.9 +/- 1.75 ng/mL, 277 +/- 7.73 ng/g, respectively) were significantly lower than those of the control healthy mothers (50.2 +/- 2.35 ng/mL, 300 +/- 6.10 ng/g, respectively) and the nonpregnant women (58.1 +/- 3.12 ng/mL, 315 +/- 7.64 ng/g, respectively). A significant decrease in concentrations of Se in serum and hair was observed in newborns with a NTD (26.0 +/- 1.55 ng/mL, 181 +/- 3.71 ng/g, respectively) compared with healthy newborns (32.6 +/- 1.70 ng/mL, 204 +/- 4.43 ng/g, respectively). CONCLUSIONS: Maternal Se deficiency during pregnancy was thought to be one of the factors responsible for NTDs. However, the lowered serum and hair Se concentrations may be secondary manifestations of an abnormal pregnancy and did not contribute to its production. More studies on maternal Se status during the antenatal period, especially early gestation and neonatal Se status including normal newborns and NTD infants, are needed.

Adult↗
PubMed2000

The changing prevalence of neural tube defects: a population-based study in the north of England, 1984-96. Northern Congenital Abnormality Survey Steering Group.

Using data from the Northern Congenital Abnormality Survey, we describe trends in the prevalence of neural tube defects (NTDs), maternal age-specific prevalence, outcome of pregnancy and the sensitivity of antenatal diagnosis of NTD-affected pregnancies in the Northern Region during 1984-96. This population-based sample consisted of 934 NTDs: there were 403 (43.1%) with anencephaly, 472 (50.5%) with spina bifida and 59 (6.3%) with encephalocele. The total prevalence at birth was 17.9 per 10,000 births and terminations (95% confidence interval [CI] = 16.7, 19.0) with a significant reduction over time (chi(2) for trend = 7.2; P = 0.007). The overall birth prevalence was 5.6 per 10,000 births [95% CI = 5.0, 6.3]; there was also a significant reduction in birth prevalence with time (chi(2) for trend = 68.3; P < 0.0001). Maternal age-specific prevalence rates decreased with increasing age. The proportion of NTD pregnancies terminated increased from 60.3% (325 cases) during 1984-90 to 78.6% (293 cases) during 1991-96, whereas the proportion of livebirths declined from 31.7% (171 cases) to 15.0% (56 cases) (P < 0.001). The sensitivity of antenatal diagnosis was consistently high for anencephaly (98%) and increased significantly for spina bifida from 60% during 1984-90 to 85% during 1991-96 (P < 0.05). Ascertainment of all cases of NTD in the Northern Region revealed a twofold reduction in birth prevalence between 1984-90 and 1991-96. This has resulted from improvements in the accuracy of antenatal detection of NTD-affected pregnancies with an increase in terminations of pregnancy.

Adult↗
PubMed1982

Evidence against oral contraceptives as a cause of neural-tube defects.

Information on oral contraceptive (OC) use, collected at the first antenatal visit, was abstracted from the medical notes in respect of 107 index pregnancies resulting in the delivery of an infant with a neural-tube defect (NTD) and 214 unaffected controls. The relative risk of having an NTD infant for women who had at any time used OCs was 0.82 (95% confidence interval 0.52, 1.32) compared with that in women who had never used OCs. For women who stopped OC use less than 3 months before becoming pregnant or who continued in early pregnancy, the relative risk was 1.18 (95% confidence interval 0.70, 1.98) compared with women who had used OCs at any other time. An analysis restricted to those women who had at any time used OCs did not suggest an association between NTD risk and the interval between stopping OC use and becoming pregnant. None of our analyses therefore provided any evidence that OCs cause NTDs and if a risk exists it can only be small.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Neural tube defects and maternal weight reduction in early pregnancy.

We present data from a case series in France of pregnant women who lost 2 to 14 kg during the first month after conception and whose fetuses developed neural tube defects (NTDs). Preliminary epidemiologic evidence from other data sets suggest that relative lack of weight gain during pregnancy may be associated with NTDs. The role of starvation, diabetes, and valproic acid in the etiology of NTDs is established. This etiologic information coupled with our data suggest an hypothesis that ketoacidosis induced by weight loss in early pregnancy is a risk factor for NTDs.

Adult↗
PubMed1999

Human transcription factor SLUG: mutation analysis in patients with neural tube defects and identification of a missense mutation (D119E) in the Slug subfamily-defining region.

Studies in mouse, chicken and Xenopus have shown that Slug is selectively expressed in the dorsal part of the developing neural tube. Ablation and antisense experiments in chicken suggest that Slug may be an important factor during neural tube closure. We therefore investigated the role of Slug as a possible candidate contributing to the aetiology of neural tube defects (NTD) in humans. We characterised the genomic structure of human SLUG including determination of the exon-intron boundaries. The coding sequence of SLUG was screened for mutations in 150 patients with NTD using single strand conformation analysis (SSCA). In one patient, we identified a missense mutation 1548C-->A in exon 2 causing an exchange of a conserved amino acid (D119E) in the Slug subfamily-defining region preceding the first zinc finger. This is the first description of a human mutation in the SLUG gene. In accordance with the findings in model organisms, the SLUG mutation may be causally related to the development of NTD in our patient and could be considered as a predisposing factor.

Adult↗
PubMed1995

Maternal serum alpha-fetoprotein screening for neural tube defects. Report of a program with more than 30000 screened pregnancies.

Maternal serum alphafetoprotein (MSAFP) screening has been set up in Asturias, in the north of Spain, in 1987 in order to make possible the prenatal diagnosis of neural tube defects (NTD) to overall pregnancy population. This large study shows the high sensitivity and specificity of MSAFP screening when it is done with absolute control of all variables such as gestational age, pregnant woman's weight, diabetes, etc. On the other hand, this study also shows a poor sensitivity second level ultrasound for the early diagnosis of NTD in the presence of spina bifidas with no bulge. We have also observed that the incidence of NTD in Asturias remained constant in the last six years, around 1.5-1.6 per 1000 pregnancies. However, due to MSAFP screening, there has been a decline in the prevalence of children born with these defects. We conclude that MSAFP screening is the best tool to identify and reduce NTD in our Region (Spain).

Female↗
PubMed1992

Recommendations for the use of folic acid to reduce the number of cases of spina bifida and other neural tube defects.

Spina bifida and anencephaly are common and serious birth defects. Available evidence indicates that 0.4 mg (400 micrograms) per day of folic acid, one of the B vitamins, will reduce the number of cases of neural tube defects (NTDs). In order to reduce the frequency of NTDs and their resulting disability, the United States Public Health Service recommends that: All women of childbearing age in the United States who are capable of becoming pregnant should consume 0.4 mg of folic acid per day for the purpose of reducing their risk of having a pregnancy affected with spina bifida or other NTDs. Because the effects of higher intakes are not well known but include complicating the diagnosis of vitamin B12 deficiency, care should be taken to keep total folate consumption at less than 1 mg per day, except under the supervision of a physician. Women who have had a prior NTD-affected pregnancy are at high risk of having a subsequent affected pregnancy. When these women are planning to become pregnant, they should consult their physicians for advice.

Anencephaly↗
PubMed1994

Mechanism of aspirin induced neural tube defect in chick embryo.

The effect of acetyl salicylic acid (aspirin) on neural tube development in chick embryo was studied, using the chick embryo blastoderm model. Aspirin was injected in four different doses sub-blastodermally into fresh embryonated eggs. The role of PGE1 and PGE2 alpha in the defect induced by aspirin on neural tube development in chick embryo was studied. PGE1 (5 micrograms) given after aspirin (30 micrograms) treatment was found to produce greater defect in development. All the four doses of aspirin used (i.e., 6, 30, 60 and 120 micrograms/embryo) produced significant changes (P < 0.01) in the neural tube development of chick embryo. Pre-treatment with PGE1 did not modify the defect induced by aspirin, whereas pre-treatment with PGF2 alpha prevented neural tube defects induced by aspirin. It appears that aspirin (in the doses used) affects neural tube formation by decreasing PGF2 alpha synthesis in chick embryo blastoderm.

Alprostadil↗
PubMed1985

Neural tube defects caused by local anesthetics in early chick embryos.

The effects of local anesthetics (ketamine HCl, lidocaine HCl, procaine HCl, and tetracaine HCl) on stage 8 (four-somite) chick embryos were investigated. In general, embryos responded to drug treatment in a dose-related manner during the first 6 hr of incubation. Concentrations of 500 micrograms/ml (ca. 2 mM) or higher were embryolethal, whereas 100-200 micrograms/ml (0.1-0.8 mM) preferentially inhibited elevation of neural folds. The latter effect was detectable within 3 hr of treatment and was readily reversible. Tetracaine was the most potent among the four local anesthetics tested at any given dose. Compared to controls, cells in the defective neuroepithelium were less elongated and exhibited smoother apical (luminal) surfaces, thinner microfilament bundles, and less intense actin-specific fluorescence. Furthermore, the effects of local anesthetics (100-200 micrograms/ml) on stage 8 chick embryos were not identical to those of cytochalasin D (0.05 micrograms/ml), colchicine (1 microgram/ml), or ionophore A23187 (25 micrograms/ml), although all treatments produced neural tube defects. Overall results suggest that local anesthetics inhibit closure of the neural tube through their disruptive action on the organization and function of microfilaments in developing neuroepithelial cells.

Anesthetics, Local↗
PubMed1994

Antenatal detection of neural tube defects: comparison of biochemical and immunofluorescence methods.

The aim of this study was to determine whether identification of glial cells in amniotic fluid samples could form a useful supplementary test in the antenatal diagnosis of neural tube defects (NTDs). In a 5-year study, 1452 samples of middle trimester amniotic fluid were examined blind to the results of other antenatal diagnostic tests and to the outcome of pregnancy. Reason of amniocentesis included raised serum alpha-fetoprotein (329), previous NTD (73), and a family history of NTDs (71). Duplicate cytospin preparations were stained with Giemsa and an antibody to glial fibrillary acidic protein (GFAP), and on this basis a prediction of fetal NTD status was made which was not communicated to clinicians. Subsequent management of pregnancies was influenced only by the results of routine antenatal testing for NTDs. Twenty cases of NTDs occurred among the 1406 cases in which the outcome was subsequently known. Of these 20 cases, only five (four anencephalic, one spina bifida) were correctly predicated by immunofluorescent identification of GFAP-positive cells in the amniotic fluid. The remaining 15 cases (two anencephalic, 13 spina bifida) were not so identified. In a further 18 cases, apparently GFAP-positive cells were identified in the absence of NTDs. We conclude that GFAP immunofluorescence examination of routine amniocentesis samples of amniotic fluid is not a useful predictive test for NTDs.

Acetylcholinesterase↗
PubMed1989

Aneuploidy with neural tube defects: another reason for complete evaluation in patients with suspected ultrasound anomalies or elevated maternal serum alpha-fetoprotein.

Some recent reports have suggested that invasive testing is unnecessary when ultrasound either confirms or refutes a neural tube defect (NTD). However, counseling for recurrence risks and the possibilities for in utero therapy would be significantly altered by an aneuploid karyotype. We report our experience with 53 pregnancies affected by NTD in which we found 13.2% of these fetuses with abnormal chromosomes. In view of the higher than previously published incidence of aneuploidy, we believe that fetal karyotypes are essential in the evaluation of all fetuses with NTDs.

Aneuploidy↗
PubMed2005

Identification of early-responsive genes correlated to valproic acid-induced neural tube defects in mice.

BACKGROUND: Valproic acid (VPA) causes the failure of neural tube closure in newborn mice. However, the molecular mechanism of its teratogenesis is unknown. This study was conducted to investigate the genomewide effects of VPA disruption of normal neural tube development in mice. METHODS: Microarray analysis was performed on the head part of NMRI mouse embryos treated for 1 hr with VPA on gestational day (GD) 8. Subsequently, we attempted to isolate genes that changed in correlation with the teratogenic action of VPA by employing reduced teratogenic VPA analogs, valpromide (VPD) and valnoctamide (VCD), in a real-time PCR study. RESULTS: Microarray results demonstrated that during neurulation, many genes, some of whose functions are known and some unknown, were either increased or decreased after VPA injection. Some genes were affected by VPD or VCD in the same way as VPA, but others were not changed by the analogs. In this way, our system identified 11 increased and 20 decreased genes. Annotation analysis revealed that the increased genes included gadd45b, ier5, per1, phfl3, pou3f1, and sox4, and the decreased genes included ccne2, ccnl, gas5, egr2, sirt1, and zfp105. CONCLUSIONS: These findings demonstrate that expression changes in genes having roles in the cell cycle and apoptosis pathways of neural tube cells were strongly expected to relate to the teratogenic, but not antiepileptic, activity of VPA. Our approach has allowed the expansion of the catalog of molecules immediately affected by VPA in the developing neural tube.

Abnormalities, Drug-Induced↗