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PubMed1994

Review of neural tube defects: risk factors in parental occupation and the environment.

We conducted a study of published work to evaluate the evidence for the hypothesis that environmental exposure and parental occupation are risk factors for neural tube defects. As other risk factors such as maternal illnesses, medication, and dietary factors have been reviewed before, this review only summarizes this information. In studies concerning environmental pollution, only a few weak associations were found. It appears that specific studies on the topic of parental occupation and neural tube defects are scarce. Therefore, studies on broader malformation categories, such as central nervous system defects, were also taken into account. Both maternal and paternal occupation seem to be associated with the occurrence of neural tube defects. However, results are not always consistent with each other, and relevant recommendations concerning prevention thus cannot be given before more studies with larger populations are conducted to confirm or refute the findings reviewed.

Environmental Health↗
PubMed1978

A comparison of neural tube defects identified by two independent routine recording systems for congenital malformations in Northern Ireland.

The efficiency of two systems for recording congenital malformations has been compared; one system, the Registrar General's Congenital Malformation Notification, is based on registering all malformed infants, and the other, the Child Health System, records all births. In Northern Ireland for three years [1974--1976], using multiple sources of ascertainment, a total of 686 infants with neural tube defects was identified among 79 783 live and stillbirths. The incidence for all neural tube defects in 8 60 per 1 000 births. The Registrar General's Congenital Malformation Notification System identified 83.6% whereas the Child Health System identified only 63.3% of all neural tube defects. Both systems together identified 86.2% of all neural tube defects. The two systems are suitable for monitoring of malformations and the addition of information from the Genetic Counselling Clinics would enhance the data for epidemiological studies.

Humans↗
PubMed1986

Comparison of an ELISA with a RIA method for serum alpha-fetoprotein determination in screening for fetal neural tube defects.

An enzyme-linked immunosorbent assay (ELISA) was evaluated for serum alpha-fetoprotein determination in the antenatal screening for fetal open neural tube defects. The ELISA was used concurrently with an existing radioimmunoassay (RIA) method until serum specimens from 5000 pregnant women, between 15 and 20 weeks gestation, had been tested. The accuracy of the ELISA was similar to that of the RIA; the median AFP values by gestational week obtained with the ELISA were, on average, 2 KIU/L higher than the corresponding RIA values; the 10th and 90th percentiles, in terms of multiples of the median (MoM), were very similar. The precision of the two methods was also similar. The ELISA method yielded 1.8% results from unaffected pregnancies above 2.5 MoM compared with 1.4% by RIA, a small but statistically significant difference (P = 0.03). Both methods detected the same affected pregnancies identified during this period; five open neural tube defects, three with exomphalos and three intra-uterine deaths. The ELISA method was simple, required about one quarter less operator time than the RIA and enabled results to be generated in one day rather than the two days required by RIA. The ELISA method is a suitable alternative to RIA for routine use in screening for fetal neural tube defects.

Enzyme-Linked Immunosorbent Assay↗
PubMed2002

Prevention of fumonisin B1-induced neural tube defects by folic acid.

BACKGROUND: The mycotoxin fumonisin B1 (FB1) inhibits sphingolipid synthesis, blocks folate transport, and has been associated with increased incidences of cancer and neural tube defects. Results from reproductive studies in animal models in vivo and in vitro have demonstrated toxicity in some cases, but no specific terata after fumonisin exposure. No information is available about folic acid's potential to protect against this toxicity. METHODS: Neurulating mouse embryos were exposed to fumonisin or folinic acid in whole embryo culture and assessed for effects on growth and development. RESULTS: Fumonisin exposure inhibited sphingolipid synthesis, reduced growth, and caused cranial neural tube defects in a dose dependent manner. Supplemental folinic acid ameliorated the effects on growth and development, but not inhibition of sphingolipid synthesis. CONCLUSION: Fumonisin has the potential to inhibit embryonic sphingolipid synthesis and to produce embryotoxicity and neural tube defects. Folic acid can reverse some of these effects, supporting results showing that fumonisin disrupts folate receptor function.

Animals↗
PubMed1995

Folic acid absorption in women with a history of pregnancy with neural tube defect.

Folic acid absorption was compared in nonpregnant women with a history of pregnancy with a neural tube defect (cases)(n = 10) with that of control women (n = 10) with a normal pregnancy history. [2H4]folic acid was administered in an oral dose (400 micrograms) to fasting case and control subjects after a 30-d saturation protocol involving daily ingestion of two 1-mg folic acid supplements. Serum and red blood cell folate concentrations were not different for case and control subjects before or during the saturation protocol (P > 0.05). The percentage (x +/- SD) of the oral dose of [2H4]folic acid excreted in 24-h urine collections postdose was not different (P > 0.05) for case compared with control subjects (9.05 +/- 2.25% and 11.10 +/- 3.41%, respectively). These data suggest that the absorption of folic acid routinely consumed in supplements and fortified food products is not impaired in women with a history of a pregnancy with a neural tube defect. Further case-controlled studies are needed to compare the absorption of the predominant dietary form of the vitamin.

Administration, Oral↗
PubMed2002

Skin graft on the surgically induced spinal open neural tube defects does not induce lipomatous malformation but enhances re-closure to the normal state in chick embryos.

To determine the effect of skin allograft on open neural tube defects (ONTDs), the neural tube was incised open using Hamburger and Hamilton stage 18 or 19 chick embryos for a length of six somites. Embryos were divided into two groups: graft and control (with and without skin allograft). On postoperative day 5, closure of ONTDs was more frequent in the graft group than in the control group (9/15 versus 0/15), and healing was nearly complete. However, typical lipomatous features were not observed. These results suggest that simple mechanical attachment of skin allograft on ONTDs does not lead to lipomatous malformation in chick embryos. On the other hand, our results support a potential role of skin allograft in the management of prenatal spinal ONTDs.

Animals↗
PubMed1981

Amniotic and maternal serum alpha-fetoprotein levels of rats with induced neural tube defects.

During the complete fetal period alpha-fetoprotein (AFP) was quantified in maternal sera and amniotic fluid from control, hypervitaminosis A and trypan blue treated normal rat fetuses, and from exencephalic and spina bifida aperta fetuses. The occurrence of histologic proven open neural tube defects was associated with amniotic fluid AFP levels that were much elevated over those of control and treated normal fetuses and those with closed neural tube defects at nearly the whole fetal period. In combining these results with the earlier reported morphologic data of the same rat fetuses as used in the present study, it is concluded that the elevation of amniotic AFP is caused by leakage of fetal serum through a disrupted and necrotic nervous tissue into the amniotic fluid. This experimental model of induced neural tube defects results in increase of amniotic fluid AFP levels similar to those found in human amniotic fluid in the presence of neural tube defects.

Amniotic Fluid↗
PubMedDate not supplied

Prevalence of neural tube defects in the province of Quebec, 1992.

A retrospective study of neural tube defects (NTDs) was carried out among elective terminations of pregnancies, stillbirths and live births to women residing in two regions of Quebec, in 1992. Primary data sources included the hospital administrative data system MEDECHO, stillborn and infant death certificates, and the list of patients seen at three spina bifida clinics. Hospital records were reviewed. A total of 30 NTD cases were identified. The prevalence rate was 1.41 per 1,000, indicating a three-fold reduction in frequency during the last three decades. All 17 cranial defects but only 5 of 13 spinal defects were diagnosed during pregnancy. Elective terminations were performed at an average gestation of 18 weeks (range 11 to 21 weeks). The MEDECHO file allows a complete identification of NTD cases, but diagnostic categories are not very specific and coding errors are present.

Abortion, Therapeutic↗
PubMed1987

Midtrimester screening for open neural tube defects: correlation of sonography with amniocentesis results.

Eight pregnancies with open neural tube defects were detected in 70 midtrimester patients referred for sonography and amniocentesis because of elevated maternal serum alpha-fetoprotein levels. Two cases of anencephaly were detected by sonography, aborted without amniocentesis, and confirmed by pathologic examination. Six cases of open spina bifida were detected through amniocentesis by elevation of alpha-fetoprotein and acetylcholinesterase levels. In only three of these six was the abnormality seen on sonography. All six pregnancies were terminated, and open spina bifida defects were confirmed on pathologic examination. Amniocentesis was 100% sensitive for diagnosis of open spina bifida, while sonography was only 50% sensitive. Our results indicate that, in patients with elevated serum alpha-fetoprotein and a normal fetal sonogram, amniocentesis should be performed to rule out open spina bifida.

Amniocentesis↗
PubMed1995

Hereditary factors in the etiology of neural tube defects. Results of a survey.

Ongoing research in the etiology of neural tube defects is increasingly being directed towards the molecular mechanisms at work in the formation of these complex lesions. We undertook to review the family history of patients in a large myelomeningocele/spina bifida clinic in an effort to identify genetic trends in these families, particularly as they relate to current research efforts and laboratory models. Surveys were received from 363 patients (35.5% of the clinic population) and analyzed. The myelomeningocele recurrence rate was 4.3%. Seven sets of twins were identified and all were discordant for their spinal lesions. A family history of spina was found to be evenly distributed between maternal and paternal relatives, rather than tending to follow through the maternal side. Epilepsy was more commonly found on the maternal side of the family, most likely reflecting the postulated causal relationship between maternal anticonvulsant use and the occurrence of spina bifida, although also possibly supporting the concept that a genetic predisposition for maternal epilepsy may also be associated with a higher frequency of birth defects among children of epileptics, independent of anticonvulsant use. Patients with spina bifida in the setting of Waardenburg syndrome and fragile X syndrome were also identified and will be discussed.

Adolescent↗
PubMedDate not supplied

Prenatal screening for neural tube defects: perceptions of potential recipients.

The interpretation of prenatal screening and follow-up diagnostic testing for neural tube defects is relatively complex and presents unusual demands in terms of informed utilization by pregnant women. Such demands could impact differentially on individuals of different socioeconomic status or cultural values. Accordingly, a two-part questionnaire, interrupted by presentation of educational material on neural tube defects and prenatal screening, was presented to female sophomore medical students and to reproductive-age women whose children were served at Howard University Hospital. Student subjects favored prenatal testing, whereas clinic subjects were divided on testing both before and after reading the educational material. Both groups anticipated prenatal screening in future pregnancies, but clinic subjects were ambiguous about the need for diagnostic follow-up after the determination of high maternal serum alpha-fetoprotein. Clinic subjects were more hesitant than students to employ abortion as a means of intervention and did not distinguish between spina bifida and anencephaly in this regard.

Female↗
PubMed1984

Anxiety during a crisis: emotional effects of screening for neural tube defects.

Anxiety was assessed in prospective mothers undergoing screening for foetal neural tube defects. Anxiety was found to be extreme and only returned to normal levels when a definitely negative amniocentesis result was communicated to the woman. Anxiety was mitigated by social and family support but other life events had little effect on it.

Amniocentesis↗
PubMed1997

Changes in cell adhesion and extracellular matrix molecules in spontaneous spinal neural tube defects in avian embryos.

Quail embryos (embryonic days 2-2.5) with spontaneous neural tube defects (NTDs), along with age-matched normal embryos, were examined immunocytochemically for the extracellular matrix (ECM) molecules laminin, fibronectin, and chondroitin sulfate proteoglycan, the cell adhesion molecules (CAMs) E- and N-cadherin and neural CAM (NCAM), and the neural crest marker HNK-1. The embryos with NTDs were at the lower limit of the normal stage range and the affected region was about 25% shorter than in normal embryos. Open NTDs occurred in cervical and upper thoracic level, although often the ventral neural tube was morphologically normal. Widened, irregular but closed neural tubes (lower thoracic to sacral levels) showed disorganized mesenchyme-like cells centrally and often multiple lumens. Finger-like tabs projecting from the ectoderm over the neural tube also occurred at lower thoracic to sacral levels. In open NTDs, the E-cadherin-labeled epidermis was incomplete dorsally, and was continuous with the N-cadherin-labeled neural tissue, with a sharp demarcation between E- and N-cadherin-expressing regions, as in the early stages of normal primary neurulation. A sharp inverted peak of epidermis extended ventrally, closely applied to the side of the neural tissue. The intervening matrix labeled less intensely for chondroitin sulfate proteoglycan relative to laminin and fibronectin, in comparison to control embryos. In closed NTDs, the dorsal superficial cell layer (i.e., positionally epidermis) was not separated from the underlying neural tissue by a band of matrix as in control embryos. In addition, this layer expressed E-cadherin (as in normal embryos), but coexpressed N-cadherin and NCAM, which are not normally found here at this stage. This overlap region resembled the mid-dorsal tissue at earlier stages in normal secondary neurulation in the tail-bud. The tabs of tissue appeared to be localized hypertrophy of the epidermal and neural ectoderm, and also showed codistribution of E- and N-cadherin. In all these defects, matrix molecules occurred within (rather than around) the neural and epidermal epithelia. HNK-1-labeled neural crest cells were frequently absent in regions of NTDs, in contrast to control embryos. These results show that matrix and cell adhesion molecules are disturbed in spontaneous NTDs at the time of neurulation, and therefore could be involved in the generation of the defects by altering cell adhesion-dependent morphogenetic events.

Animals↗
PubMed1991

Prevalence of neural tube defects in 20 regions of Europe and the impact of prenatal diagnosis, 1980-1986. EUROCAT Working Group.

STUDY OBJECTIVE: The aims were (1) to determine whether in Europe, 1980-86, geographical differences in total prevalence of neural tube defects persist; (2) to examine the stability of total prevalence rates over time; (3) to evaluate the impact of prenatal diagnosis in terms of frequency and timing of termination of pregnancy. DESIGN: Prevalence rates of neural tube defects were determined from case registration data in 20 EUROCAT regional registers of congenital anomalies, 1980-86. The chi 2 test for homogeneity in proportions was used to test whether differences in total prevalence rates were significant between regions or over time. SETTING: Geographically defined populations were used in the Republic of Ireland, United Kingdom, Belgium, The Netherlands, Luxemburg, Denmark, France, Italy, Yugoslavia, and Malta. PATIENTS: The patients were 3113 cases of anencephaly, spina bifida, encephalocele, and iniencephaly. Total cases (livebirths, stillbirths and induced abortions following prenatal diagnosis) were registered in 14 regions. Induced abortions were excluded from registration in six regions. MEASUREMENTS AND MAIN RESULTS: Total prevalence rates (including livebirths, stillbirths and induced abortions) were 24 to 38 per 10,000 in six areas of Ireland and United Kingdom. Average total prevalence rate in eight continental European areas was 11.5 per 10,000. There was a secular decline in total prevalence in Dublin (Republic of Ireland) and Northern Ireland (United Kingdom) and a fluctuation in Glasgow, Liverpool, and South Glamorgan (United Kingdom). Total prevalence in continental Europe was stable over time. There was no significant geographical or secular variation in the spina bifida to anencephaly ratio (1.3). The ratio of encephalocele to other neural tube defects was lower in the British Isles (0.09) than in continental Europe (0.18). The impact of prenatal diagnosis and termination of pregnancy is increasing over time. Terminations were performed 1984-86 in at least 80% of total cases of anencephaly in 6/11 centres registering induced abortions, and in at least 40% of total cases of spina bifida in four centres. Serum alpha fetoprotein screening in British centres was associated with earlier prenatal diagnosis of spina bifida than ultrasound screening in other centres. CONCLUSIONS: Geographical and secular variation in total prevalence of neural tube defects persists in Europe 1980-86, independent of the practice of prenatal diagnosis. There is considerable regional variation in the impact of prenatal diagnosis in terms of frequency and timing of diagnosis and pregnancy termination linked to different policies and practices of prenatal screening.

Abortion, Induced↗
PubMed1990

[The prevention and prenatal diagnosis of neural tube defects].

The AA. provide with the schemes for the study of Neural Tube Defects (D.T.N.) yet the continuation and the prevention of NTD'S clinical cases. Also, the AA. show a protocol of action. It is indispensable for all the Spina Bifida Sections to work together by means of an Orthogenesis and Familiar Planning Unit.

Acetylcholinesterase↗
PubMed1992

High levels of maternal serum alpha-fetoprotein and human chorionic gonadotrophins leading to the diagnosis of combined neural tube defect and partial mole.

A case of combined partial mole and neural tube defect is presented. The detection of high levels of both maternal serum (MS) alpha-fetoprotein (AFP) and human chorionic gonadotrophin (hCG) during the second trimester led to the ultrasonic demonstration of anencephaly, omphalocele, and partial mole. This is the first report of combined elevation of MSAFP and MShCG.

Adult↗
PubMed2004

Trends in neural tube defects in Western Australia in Indigenous and non-Indigenous populations.

Neural tube defects (NTD) were 43% more common in Indigenous than in non-Indigenous infants in Western Australia in the 1980s, and there has been a fall in NTD overall in Western Australia since promotion of folate and voluntary fortification of food has occurred. In order to investigate whether the fall had occurred in both indigenous and non-Indigenous infants, data on NTD (births and terminations) were obtained from the WA Birth Defects Registry, and on all births from the Maternal and Child Health Research Data Base. Knowledge of folate was asked in a survey of indigenous women interviewed postpartum. Before the promotion of folate (1980-92), there has been a 42% increase in NTD in Indigenous compared with non-Indigenous infants (prevalence ratio (PR)=1.42 [95% confidence interval (CI) 1.04, 1.94]); while in the most recent period (1996-2000), the prevalence in Indigenous infants was almost twice that of non-Indigenous infants (PR 1.98 [CI 1.25, 3.15]). Fifty-five per cent of Indigenous women knew about folate in pregnancy. Similar to sudden infant death syndrome, this study has highlighted health promotion that has been successful in reducing the risk of a childhood condition overall, but has failed to be effective for Indigenous children.

Adolescent↗
PubMed2003

Diet quality and risk of neural tube defects.

Many studies have examined the impact of single nutrients on neural tube defect (NTD) risk, particularly folate. The impact of dietary patterns or nutrients in combination has received much less attention. This study examines the association of diet quality with NTD risk, using food frequency data from a population-based case-control study of NTDs (n=454 cases and 462 controls). The diet quality score was based on low (<10th percentile among controls) versus high (>90th percentile) values for intakes of iron, vitamins B(6) and A, calcium, folate, and percentage of kilocalories from fat and from sweets (range=0-14). Women with a low score (i.e., <4, or <10th percentile) had an elevated risk of an NTD-affected pregnancy (odds ratio 1.6, 95% CI 1.0-2.6). Stratified analyses suggested that the effect may be restricted to certain groups of women who may be at greater nutritional risk (i.e., women who did not take vitamin supplements or regularly consume breakfast cereals before pregnancy).

Adult↗