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PubMed2002

Chronology of neurological manifestations of prenatally diagnosed open neural tube defects.

OBJECTIVE: To evaluate the incidence and chronology of sonographic markers of neurological compromise in prenatally diagnosed neural tube defects. METHODS: We reviewed our ultrasound database from 1988 to 1999 to identify all cases of prenatally diagnosed neural tube defects. All patients received an initial detailed targeted ultrasound evaluation with subsequent evaluations every 4-6 weeks. Cases involving multiple congenital anomalies, aneuploidy, or inadequate follow-up were excluded. Specific ultrasound markers assessed included the presence of ventriculomegaly (> 10 mm) and clubfoot. RESULTS: Forty-seven cases of neural tube defects were identified over the study interval. After exclusions, 42 cases were available for evaluation. The overall incidence of ventriculomegaly and clubfoot in the study cohort was 86% and 38%, respectively. In the 33 patients with initial ultrasound examination performed at < 24 weeks' gestation, 76% (25/33) had evidence of ventriculomegaly and 30% (10/33) and clubfoot. Only 9% (1/11) of the patients managed expectantly developed evidence of ventriculomegaly and 3/11 (27%) developed clubfoot from the time of the initial ultrasound examination to delivery. CONCLUSIONS: Ultrasound markers of neurological compromise are early and frequent findings associated with fetal neural tube defects. Development of ventriculomegaly is an uncommon occurrence later in gestation, while the risk for developing clubfoot appears to increase as gestation progresses.

Adult↗
PubMed2003

Maternal serum B12 levels and risk for neural tube defects in a Texas-Mexico border population.

PURPOSE: Neural tube defects (NTDs) are common birth defects that can be prevented with folate fortification and supplementation. Studies suggest that other nutrients may also be essential to neural tube closure and have a potential role in risk reduction, with vitamin B(12) mentioned most often. We determined the effect of maternal serum B(12) levels, measured postpartum, on the risk of NTDs among a high risk Mexican American population. METHODS: The case-control study included 157 Mexican American women with NTD-affected pregnancies and 186 Mexican American women with normal pregnancies, who were residents of Texas-Mexico border counties and delivered during 1995 to 2000. RESULTS: Compared with women in the highest vitamin B(12) quintile, women in the lowest quintile showed a strong risk effect (odds ratio (OR) = 3.0, confidence interval (CI): 1.4, 6.3); while those in the 2nd and 3rd quintiles showed moderate risk effects (OR = 1.6, CI = 0.7, 3.6 and OR = 1.7, CI = 0.8, 3.8, respectively). Adjusting for obesity, vitamin supplements, dietary folate, dietary B(12), red blood cell folate, and other covariates did not materially change these estimates. CONCLUSIONS: Insufficient levels of serum B(12), which are not normally indicative of a classical vitamin B(12) deficiency nor stem from an inadequate diet, may be an important etiologic factor for NTDs in this population.

Adult↗
PubMed1990

Neural tube defects: are neurulation and canalization forms causally distinct?

Neural tube defects (NTD) may be separated according to the overall location and probable embryological origin into 2 groups: upper or neurulation defects, and lower or canalization defects. Evidence as to whether these 2 forms are causally related or distinct was sought from 2 sources. Families with more than one NTD individual were studied to examine whether there was concordance within sibships for these 2 types of lesion. Seven of the 38 sibships were discordant (18%). Eight of the 10 cases of NTD that had arisen despite maternal periconceptional vitamin supplementation were neurulation defects and 2 were canalization defects. Both observations suggest that upper and lower types of NTD are causally related, and offer no support for the suggestion that they are distinct.

Humans↗
PubMed1994

Neural tube defects and maternal serum zinc and copper concentrations in mid-pregnancy: a case-control study.

OBJECTIVE: To assess the relationship between mid-pregnancy maternal serum zinc and copper concentrations and neural tube defects. DESIGN: A prospective case-control study during 1978-1988 within a statewide hospital-based neural tube defect screening program measuring maternal serum alpha-fetoprotein levels at mid-pregnancy. SUBJECTS: Cases were 69 women with fetuses with confirmed neural tube defects. Controls were 592 women with fetuses without neural tube defects who were individually matched to cases for hospital, calendar date of screening, age and parity; there was a variable control-to-case ratio. RESULTS: For both unmatched and adjusted matched analyses, mean maternal serum zinc concentration was higher in cases than controls (P = 0.02 and P = 0.03, respectively). There were no case-control differences for serum copper concentrations. Conditional logistic regression analysis showed a (statistically non-significant) 50% increase in risk of neural tube defects in women whose serum zinc concentration was more than two standard deviations above the population mean. CONCLUSION: Within the normal range of maternal serum zinc and copper concentrations there is no variation in risk of neural tube defects. However, women with very high serum zinc levels may have an increased risk of neural tube defects. This could reflect deficient maternal-to-fetal transfer of zinc in some of those individuals. Any such phenomenon would be manifest in observational, but not experimental, studies.

Adult↗
PubMed1996

Homocysteine and neural tube defects.

It is now well established that folic acid, when taken periconceptionally, can prevent many neural tube defects. It is also becoming clear that folic acid does not work by correcting a nutritional deficiency in pregnant women. Rather, it appears that a metabolic defect is responsible for these neural tube defects and that this defect or defects can be corrected by a sufficiently large dose of folic acid. Our recent work demonstrates that homocysteine metabolism is likely to be the critical pathway affected by folic acid. We have demonstrated significantly higher homocysteine levels in women carrying affected fetuses than in control women. These findings indicate that one of the enzymes responsible for homocysteine metabolism is likely to be abnormal in affected pregnancies. Animal studies suggest that the conversion of homocysteine to methionine could be the critical step. Rat embryos in culture require methionine for neural tube closure. Methionine synthase, cystathionine synthase, and 5,10 methylene tetrahydrofolate reductase are all important in the metabolism of homocysteine in humans. If methionine synthase is the critical enzyme, it would raise the interesting public health issue that vitamin B-12 might be able to stimulate the abnormal enzyme as folic acid does. Adding vitamin B-12 might make it possible to reduce the dose of folic acid required in fortified food, thus allaying concerns about overexposure to folic acid.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1982

Sonography as a procedure complementary to alpha-fetoprotein testing for neural tube defects.

Forty-four fetuses were studied sonographically because of an elevated amniotic fluid alpha-fetoprotein level noted during routine amniocentesis, questionable findings during an ultrasound examination at another institution, or a history of a neural tube defect in prior pregnancy. Eleven neural tube defects, 16 non-neural tube defect anomalies, and 17 normal fetuses were all correctly identified by sonography. Ultrasound answers the need for a second diagnostic tool to complement the alpha-fetoprotein measurement.

Amniotic Fluid↗
PubMedDate not supplied

[Neural tube defects. The 10-year experience of a central maternity hospital].

OBJECTIVES: 1) To determine trends in prevalence of neural tube defects and the impact of therapeutic abortion. 2) To review perinatal management of spina bifida. DESIGN: All spontaneous and therapeutic abortions, still births and live births affected by neural tube defects registered in Alfredo da Costa Maternity in Lisbon, from 1983 to 1992, were retrospectively analysed. RESULTS: Eighty-two cases with neural tube defects are reported and myelomeningocele and anencephaly++ were the most frequent ones. Total prevalence for all defects was 0.78:1000 births with a small upward trend during the last two years. Birth prevalence was 0.6:1000, with a clear downward trend, due to therapeutic abortion. Prenatal diagnosis improved significantly, from 9% of all defects detected in 1983-87 to 77.5% in 1988-92. Since 1989, all cases of anencephaly were detected before birth. Most cases of spina bifida were vaginally delivered, and elective cesarean section occurred in 4. Early closure of the defect was undertaken in 87.6% of the newborns with open spina bifida. CONCLUSION: While total prevalence of neural tube defects remained stable, with only a small upward trend, prenatal diagnosis and therapeutic abortion resulted in a 56.3% fall in birth prevalence. Optimal management of open spina bifida demands a multidisciplinary team with an individual program for each case.

Female↗
PubMed2004

Parental employment status and neural-tube defects and folic acid/multivitamin supplementation in Hungary.

OBJECTIVE: To study the role of parental employment status as indicator of socio-economic status (SES) in the origin of neural-tube defect (NTD) and in the use of periconceptional folic acid/multivitamin supplementation. MATERIALS AND METHODS: One thousand two hundred and two cases with neural-tube defects, 38,151 population controls without any defects and 22,475 patient controls with other defects were compared in the population-based data set of the Hungarian case-control surveillance of congenital abnormalities, 1980-1996. RESULTS: The proportion of professionals was lower, while the proportion of semi- and unskilled workers was higher in the neural-tube defect group compared with the population control group. However, the comparison of neural-tube defect and patient control groups showed a lower socio-economic status in the patient control group. In addition, the socio-economic status of fathers in the neural-tube defect group seemed to be better than in the population and patient control groups. The higher periconceptional folic acid supplementation and the higher use of multivitamins during pregnancy occurred in the professional and managerial categories in all the three study groups. CONCLUSION: The occurrence of neural-tube defect shows a slight socio-economic dependence in the mothers at the comparison with population control group, however, patient control group had the lowest socio-economic status. The higher maternal education goes together with a higher proportion of periconceptional folic acid supplementation.

Adult↗
PubMed2004

Neural tube defects and associated anomalies in South Carolina.

BACKGROUND: Neural tube defects (NTDs) occur as isolated malformations and in the company of other birth defects. This study was conducted to determine the frequency of coexisting anomalies and the relationship between them. METHODS: Since 1992, NTDs have been identified through prenatal and postnatal surveillance activities in South Carolina. The type of NTD and presence of associated anomalies were determined by prenatal ultrasound, postnatal and/or postmortem examination. RESULTS: During the ten-year period from 1992 to 2002, 564 NTDs were identified by the surveillance system. Seventeen percent of NTDs (98/564) had associated malformations. In approximately half (n = 51) of these cases, the NTDs and associated anomalies were components of a recognizable syndrome. In the remaining cases (n = 47), no syndrome was identified or suspected, but the associated anomalies were believed in most instances to be secondary to space limitation or neural crest abnormalities imposed by the NTD. CONCLUSION: Seventeen percent of NTDs in South Carolina have associated malformations. In most cases, the associated anomalies are considered either components of a multiple malformation syndrome or secondary to the NTD.

Adult↗
PubMed1984

The improvement of the antenatal detection of fetal neural tube defects using discriminant analysis.

Discriminant analysis was applied to the antenatal diagnosis of fetal neural tube defects. Alpha-fetoprotein, gestational age, and seven easily assayed biochemical variables were used to generate the discriminant function, which was derived from a retrospective study on data from 130 pregnancies, including 25 which were associated with fetal anencephaly and 13 with fetal spina bifida. This function was used to generate a diagnosis in a blind study of 40 previously unassayed samples: 20 problem samples from another centre interspersed with 20 normal samples. The same function was used over a period of 2 years to predict prospectively the outcome of 669 pregnancies with respect to neural tube defects. Of these 55 were found to be associated with fetal neural tube defects. Classification is shown to be more reliable than using alpha-fetoprotein and gestational age alone. The results demonstrate a successful application of discriminant analysis to medical diagnosis.

Amniotic Fluid↗
PubMedDate not supplied

Preventing neural tube defects in Europe: a missed opportunity.

Each year, more than 4500 pregnancies in the European Union are affected by neural tube defects (NTD). Unambiguous evidence of the effectiveness of periconceptional folic acid in preventing the majority of neural tube defects has been available since 1991. We report on trends in the total prevalence of neural tube defects up to 2002, in the context of a survey in 18 European countries of periconceptional folic acid supplementation (PFAS) policies and their implementation. EUROCAT is a network of population-based registries in Europe collaborating in the epidemiological surveillance of congenital anomalies. Representatives from 18 participating countries provided information about policy, health education campaigns and surveys of PFAS uptake. The yearly total prevalence of neural tube defects including livebirths, stillbirths and terminations of pregnancy was calculated from 1980 to 2002 for 34 registries, with UK and Ireland estimated separately from the rest of Europe. A meta-analysis of changes in NTD total prevalence between 1989-1991 and 2000-2002 according to PFAS policy was undertaken for 24 registries. By 2005, 13 countries had a government recommendation that women planning a pregnancy should take 0.4mg folic acid supplement daily, accompanied in 7 countries by government-led health education initiatives. In the UK and Ireland, countries with PFAS policy, there was a 30% decline in NTD total prevalence (95% CI 16-42%) but it was difficult to distinguish this from the pre-existing strong decline. In other European countries with PFAS policy, there was virtually no decline in NTD total prevalence whether a policy was in place by 1999 (2%, 95% CI 28% reduction to 32% increase) or not (8%, 95% CI 26% reduction to 16% increase). The potential for preventing NTDs by periconceptional folic acid supplementation is still far from being fulfilled in Europe. Only a public health policy including folic acid fortification of staple foods is likely to result in large-scale prevention of NTDs.

Adult↗
PubMed1998

Embryonic folate metabolism and mouse neural tube defects.

Folic acid prevents 70 percent of human neural tube defects (NTDs) but its mode of action is unclear. The deoxyuridine suppression test detects disturbance of folate metabolism in homozygous splotch (Pax3) mouse embryos that are developing NTDs in vitro. Excessive incorporation of [3H]thymidine in splotch embryos indicates a metabolic deficiency in the supply of folate for the biosynthesis of pyrimidine. Exogenous folic acid and thymidine both correct the biosynthetic defect and prevent some NTDs in splotch homozygotes, whereas methionine has an exacerbating effect. These data support a direct normalization of neurulation by folic acid in humans and suggest a metabolic basis for folate action.

Animals↗
PubMed1982

Neural tube defects in Havana City--incidence and prenatal diagnosis.

An evaluation was made of all cases of neural tube defects born in seven gynaecological hospitals and obstetric centres of Havana, between 1970 and 1980. Neural tube defects were recordable from 492 infants out of 319,228 births. The families concerned were briefed in human genetics and informed about the possibility of prenatal diagnosis of anencephaly and bifid spine (spina bifida aperta). Some of them had a record of this defect. Amniocentesis was applied to 30 women with an empirical risk of 1:20, and alphafoetoprotein was analysed in their amniotic fluid. Anencephaly was diagnosed in one case and confirmed by termination of pregnancy. The occurrence of neural tube defects usually is of spontaneous nature, and incidence is relatively high. Therefore efforts are now being made to introduce a scheme of prenatal screening based on alphafoetoprotein assessment in the serum of pregnant women.

Amniocentesis↗
PubMed1989

[Quantitative acetylcholinesterase (AChE)--determination in amniotic fluid--potential for differential diagnosis in consistently high AFP levels during general AFP screening for prenatal diagnosis of open neural tube defects].

Measurement of maternal serum alpha-fetoprotein concentration for prenatal detection of open neural tube defects had been introduced into the obstetrical care of pregnant women in the district of Schwerin since 1983. In cases of high risk for presence of an open neural tube defect, noticed by elevated levels of maternal serum alpha-fetoprotein concentration step by step further diagnostic steps are necessary. In addition to special examination by ultrasound and measurement of alpha-fetoprotein concentration in amniotic fluid quantitative analysis of acetylcholinesterase activity in amniotic fluid seems to be valuable. Reliability of detecting open neural tube defects in prenatal care had been proved by quantitative analysis of acetylcholinesterase activity in amniotic fluid. The existing results up to now were very reliable, especially biological transit stages from normal to pathological findings were taken into consideration, too. In these cases further controls are necessary. Levels of acethylcholinesterase activity below the 90th percentile can be considered as normal findings, levels above the 99th percentile must be interpreted as pathological findings. These are our experiences up to date.

Acetylcholinesterase↗
PubMed2000

Role of amniotic fluid homocysteine level and of fetal 5, 10-methylenetetrahydrafolate reductase genotype in the etiology of neural tube defects.

A mutation in the gene 5,10-methylenetetrahydrofolate reductase (MTHFR), leading to altered homocysteine metabolism, has been identified in parents and fetuses with fetal neural tube defects. We sought to determine which is of greater importance in fetal neural tube defect formation: the fetal MTHFR mutation or elevated amniotic fluid homocysteine level. We retrieved stored amniotic fluid from cases of isolated fetal neural tube defect diagnosed from 1988 to 1998 (n = 80), and from normal controls matched for race, month and year of amniocentesis, and maternal age. The presence or absence of the 677C-->T mutation of MTHFR was determined and homocysteine levels were measured; cases and controls were compared. Significantly more cases than controls were heterozygous or homozygous for the 677C-->T MTHFR mutation (44% vs 17%, P < or = 0.001). Cases were also significantly more likely than controls to have an amniotic fluid homocysteine level above the 90th centile (>1.85 micromol per liter); 27% vs 10%, P = 0.02. Thirty one cases and 12 controls had an abnormal genotype; however, amniotic fluid homocysteine levels were not significantly different between these two groups (6/31, or 19% of cases had an elevated homocysteine compared to 1/12, or 8% of controls; P = 0.65). In contrast, 40 cases and 60 controls had a normal genotype; the neural tube defect cases had significantly higher homocysteine levels (13/40, or 32% of cases had an elevated homocysteine level compared to only 6/60, or 10% of controls; P = 0.008). Although both abnormal fetal MTHFR genotype and abnormal amniotic fluid homocysteine concentration are significantly associated with neural tube defects, the association with amniotic fluid homocysteine concentration is significant regardless of the fetal MTHFR genotype. The relationship between maternal and fetal homocysteine metabolism is complex.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMedDate not supplied

Zinc-deficient sprouting blight potatoes and their possible relation with neural tube defects.

Maternal nutritional zinc deficiency is blamed in the pathogenesis of neural tube defects. In animal and plant domains zinc is required for growth and development. The objective of the present study was to show that sprouting blighted potato tuber is zinc deficient. In five potato varieties, zinc was measured by atomic absorption spectrophotometry in wet-ashed paired slices of edible potato tuber and in its peel, in blighted potato tuber and in its sprout. Zinc contents were measured as the mean (+/- SEM) and the following values were found, 0.388 +/- 0.036, 0.623 +/- 0.059, 0.550 +/- 0.030 and 1.089 +/- 0.181 mg per 100 g wet weight, respectively. In conclusion, we believe that long-term consumption of zinc-depleted, blight potato tuber by pregnant woman could be potentially teratogenic with the consequent birth of a baby with neural tube defects.

Maternal Nutritional Physiological Phenomena↗
PubMed1998

[Open neural tube defects in prenatal diagnosis].

The problem of open neural tube defects (ontd) is discussed in the light of results of prenatal tests performed in the district of Warsaw. These results seem to bear some epidemiological significance allowing estimation of approximate frequency of ontd as well as recurrence risk for the purpose of genetic counselling. Prenatal diagnosis of ontd is very important for individual families--particularly those with increased risk. However, in view of very small number of prenatal tests and the fact that maternal serum screening and ultrasonografic screening are practically not available the demographic impact of prenatal diagnosis in Poland on the frequency of ontd (and other genetic diseases) in Poland must be negligible.

Acetylcholinesterase↗