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PubMed1986

Neural tube defects among rural blacks in a Transkei district. A preliminary report and analysis.

A retrospective review of the records of 9 142 deliveries occurring during the 5 calendar years 1980-1984 was undertaken to determine the incidence of neural tube defects (NTDs) among black babies in the rural Transkei district of Umzimkulu. The hospital incidence of 6.13 as well as the extrapolated district-wide incidence of 3.79 NTDs/1 000 births found in this study is markedly higher than the reported rates for the black population in southern Africa (1.3/1 000), and raises the possibility that NTDs may be more prevalent among blacks in some areas of this region than has previously been realized. Factors possibly favouring an increased rate in this area are discussed; and it is planned to continue local NTD surveillance prospectively by means of registries at selected hospitals. NTD characteristics by seasonality and female preponderance appeared to be valid in this group.

Black or African American↗
PubMed1997

Promotion of folate for the prevention of neural tube defects: knowledge and use of periconceptional folic acid supplements in Western Australia, 1992 to 1995.

To assess changes in knowledge and use of folic acid supplements in relation to a statewide health promotion project for the prevention of neural tube defects, we surveyed general practitioners, pharmacists, women of child-bearing age and pregnant women in Western Australia. We also collected data on wholesale sales of folic acid supplements. By the end of the project, 56.5 per cent of general practitioner respondents knew that the recommended dose of folic acid was 0.5 mg and 70 per cent offered folic acid supplements to women planning pregnancy, 82.5 per cent of responding pharmacists knew the recommended dose, and 87.5 per cent reported an increase in sales of 0.5 mg folic acid. Wholesale sales of 0.5 mg folic acid increased markedly in Western Australia compared with other states. From shopping centre surveys of women of child-bearing age we estimated that their knowledge of the association between folate and spina bifida increased from 8.2 per cent before the project to 67.5 per cent 2.5 years later, and doctors were a major source of information for women. In a 1995 survey of a sample of pregnant women, 43.1 per cent with planned pregnancies had taken folic acid supplements periconceptionally, compared with 19.1 per cent in a similar survey in 1993.

Adult↗
PubMed1999

The "thermolabile" variant of methylenetetrahydrofolate reductase and neural tube defects: An evaluation of genetic risk and the relative importance of the genotypes of the embryo and the mother.

Recent reports have implicated the "thermolabile" (T) variant of methylenetetrahydrofolate reductase (MTHFR) in the causation of folate-dependent neural tube defects (NTDs). We report herein the largest genetic study of NTD cases (n=271) and families (n=218) to date, establishing that, in Ireland, the "TT" genotype is found in 18.8% of cases versus 8.3% of controls (odds ratio 2.57; confidence interval [CI] 1.48-4.45; P=.0005). The maternal and paternal TT genotypes have intermediate frequencies of 13.8% and 11.9%, respectively, indicating that the predominant MTHFR-related genetic effect acts via the TT genotype of the developing embryo. Analysis of the 218 family triads of mother, father, and affected child with log-linear models supports this interpretation, providing significant evidence that the case TT genotype is associated with NTDs (P=.02) but no evidence of a maternal TT genotypic effect (P=. 83). The log-linear model predicted that the risk of NTDs conferred by the case TT genotype is 1.61 (CI 1.06-2.46), consistent with the paramount importance of the case TT genotype in determining risk. There is no compelling evidence for more than a modest additional risk conferred by a maternal TT genotype. These results favor a biological model of MTHFR-related NTD pathogenesis in which suboptimal maternal folate status imposes biochemical stress on the developing embryo, a stress it is ill-equipped to tolerate if it has a TT genotype.

Alleles↗
PubMed1982

Electrophoretic mobility of lymphocytes in neonates with cleft lip/palate and neural tube defect: a pilot study.

This study examined the surface charge of lymphocytes in newborns with fusion-type defects. Significant difference was found in the electrophoretic mobility of cells between normal controls (0.89 +/- 0.02) and neonates with cleft lip/palate (1.01 +/- 0.02; P less than 0.01) or neural tube defect (0.99 +/- 0.02; P less than 0.02). The cell frequency/mobility histograms revealed unimodal distribution for controls, but bimodal distribution for malformed infants of both types. It is suggested that alterations in the genetically determined cell surface charge properties might play an important role in fusion-type defects.

Cell Membrane↗
PubMed1997

Folate supplementation and neural tube defects: a review of a public health issue.

Folate deficiency is one of today's most common vitamin deficiencies in women. Women who consume a low level of folate during pregnancy are at risk for poor pregnancy outcomes including neural tube defects (NTD). However, other factors such as heredity, social class, maternal age, birth order, maternal diet, length of time between pregnancies, maternal zinc deficiency, use of anticonvulsant drugs, abnormal homocysteine metabolism and the use of oral contraceptives, have also been implicated as causes of NTD. Animal studies have shown that fetuses are highly dependent on the folate status of the mother. In addition, several retrospective and prospective human studies have provided evidence that folate lowers the incidence of NTD.

Animals↗
PubMed2000

Developmental eye and neural tube defects in the eye blebs mouse.

In the mouse, eye blebs (eb) is a spontaneous mutation that presents a useful model for the study of abnormal eye development. Since its initial description three decades ago, little information has been generated regarding the developmental course of eb eyes. Although the gene for eb has not been identified, much can be learned from the developmental defects present in the eb mouse. First detected in the eye at embryonic day 11.5 (E11.5), the eb defect is observed as an increased vascularization throughout the developing eye and head region. As development proceeds, the embryonic eye fills with blood, and the resulting hematoma distorts the shape of the iris. The eyelids fail to close, and animals are born with open eyes. Lens degeneration and retinal folding are characteristic of eb, as are microphthalmia and thick, disorganized irises. A second presentation of the eb defect is disruption of neural tube closure in the anterior and hindbrain neuropores. These eb animals are born with open neural tubes but with apparently normal eyes.

Animals↗
PubMed1978

The importance of accurate gestational age estimation in screening for fetal neural tube defects using maternal serum alpha-fetoprotein levels.

Estimates of gestational age based on menstrual history are often in error, often by as much as 4 weeks. The effect of this problem with respect to a screening program for neural tube defects based on maternal serum alpha-fetoprotein determination is examined. The variance of alpha-fetoprotein values for serum samples assigned to gestational age categories from 15 to 19 weeks of gestation based on menstrual history and that of samples classified according to sonographic estimates do not show clear-cut differences. However, when an individual sample is referred to a calibration curve of normal values, errors in gestational age estimates significantly increase the possibility of a false positive/false negative decision for high-level percentile classification. The effect of such an error is least at 16 to 17 weeks of gestation.

Amniocentesis↗
PubMed1977

Amniotic fluid fibrinogen degradation products in the prenatal diagnosis of neural tube defects.

Elevated levels of fibrin(ogen) degradation products (FDP) have been detected in second-trimester amniotic fluid in association with open neural tube defects (NTD'S) in the fetus. The FDP assay has been proposed for the prenatal diagnosis of NTD's and in this paper is compared with the established use of the alpha-fetoprotein (AFP) assay. FDP and AFP levels were measured in 132 amniotic fluid samples, including 20 NTD cases. The false negative and false positive rates for the FDP assay are high compared with the AFP assay, but it may be of value as an adjunct assay to reduce the over-all false positive rate.

Amniocentesis↗
PubMed1987

Neural tube defects in Beijing-Tianjin area of China. Urban-rural distribution and some other epidemiological characteristics.

Records in the obstetric wards and nurseries of 18 hospitals were reviewed and studied epidemiologically, covering about 210,000 deliveries and 1000 cases of neural tube defects (NTD). All live and still births occurred in the period 1970-84. Following the NTD classification used by Koch (1984), our case series consisted of anencephalus 50.3%, spina bifida 44.2%, and NTD with other system defects 5.5%. Overall NTD prevalence rate at birth was 4 per thousand, obviously higher than those in most other countries. Marked urban-rural differences in NTD prevalence rate at birth were observed. The rate in rural areas after correction for selection bias was still as high as 7.25 per thousand. As compared with cities and suburbs, the relative risk of NTD born to mothers in rural regions was 2.4. The male-to-female ratios were much less than 1 for various kinds of NTD. Looking at the effect of maternal age and birth order simultaneously in 12 different settings, it can be seen that prevalence of NTD was moderately higher among second and third births to women aged less than or equal to 24 and those greater than or equal to 35 years of age.

Adult↗
PubMed2005

Maternal exposure to arsenic, cadmium, lead, and mercury and neural tube defects in offspring.

Arsenic, cadmium, lead, and mercury are neurotoxins, and some studies suggest that these elements might also be teratogens. Using a case-control study design, we investigated the relation between exposure to these heavy metals and neural tube defects (NTDs) in offspring of Mexican-American women living in 1 of the 14 Texas counties bordering Mexico. A total of 184 case-women with NTD-affected pregnancies and 225 control-women with normal live births were interviewed about their environmental and occupational exposures during the periconceptional period. Biologic samples for blood lead and urinary arsenic, cadmium, and mercury were also obtained for a subset of these women. Overall, the median levels of these biomarkers for heavy metal exposure did not differ significantly (P > 0.05) between case- and control-women. However, among women in the highest income group, case-women were nine times more likely (95% confidence interval (CI) 1.4-57) than control-women to have a urinary mercury 5.62 microg/L. Case-women were 4.2 times more likely (95% CI 1.1-16) to report burning treated wood during the periconceptional period than control-women. Elevated odds ratios (ORs) were observed for maternal and paternal occupational exposures to arsenic and mercury, but the 95% CIs were consistent with unity. The 95% CIs of the ORs were also consistent with unity for higher levels of arsenic, cadmium, lead, and mercury in drinking water and among women who lived within 2 miles at the time of conception to industrial facilities with reported emissions of any of these heavy metals. Our findings suggest that maternal exposures to arsenic, cadmium, or lead are probably not significant risk factors for NTDs in offspring. However, the elevated urinary mercury levels found in this population and exposures to the combustion of treated wood may warrant further investigation.

Adult↗
PubMed2006

Maternal herpes labialis in pregnancy and neural tube defects.

According to previous case reports, some congenital abnormalities (CAs) of the brain, such as microcephaly, are a result of intrauterine herpes simplex virus infection. A population-based case-control study was conducted to determine the risk of neural tube defects (NTDs) after maternal herpes labialis infection during pregnancy. Data were taken from the Hungarian Case-Control Surveillance of Congenital Abnormalities from 1980 to 1996, which included 1202 children with NTDs and 21641 comparison children with CAs other than NTDs. The adjusted relative risks (odds ratio [OR]) for NTDs associated with maternal herpes labialis in the first trimester of pregnancy was OR 1.19 (95% confidence interval [CI] 0.68-2.06), and in the entire pregnancy was OR 0.94 (95% CI 0.61-1.44). Self-reported maternal herpes labialis during pregnancy was not associated with a substantially increased risk of NTDs in infants.

Adult↗
PubMed1990

Anencephaly: its spectrum and relationship to neural tube defects.

Anencephaly patients are of renewed interest because they are regarded as a potential source of organ donation. While there has been a longstanding scientific curiosity on this subject, studies have frequently included such cases as part of the larger spectrum of neural tube defects (NTDs). This paper will discuss some unusual features of anencephaly. Following a review of classification and pathogenesis, associated malformations, growth parameters (organ size and anthropometric measurements), and associations with other entities are discussed. Finally, the relationship of anencephaly to NTDs is presented.

Abnormalities, Multiple↗
PubMed1987

Studies in neural tube defects. I. Epidemiologic and etiologic aspects.

In the NIH Collaborative Perinatal Project, a prospective study of over 53,000 pregnant women and their offspring, 71 single-born children (13.33/10,000) were found to have a non-syndromal neural tube defect (NTD). A family history was present in only one case. The group of individuals with NTD was compared to a group of 400 randomly selected non-malformed control infants. Of over 50 maternal factors studied the following showed significant association with NTD in the offspring: diabetes mellitus; organic heart disease; lung disease; and diuretic, antihistamine, and sulfonamide use. The interval between the termination of the immediately previous pregnancy and the start of the proband pregnancy was significantly shorter in mothers of NTD children than in mothers of control infants. The risk for NTD was also significantly increased if the immediately previous pregnancy was a spontaneous abortion. There was no increased risk for NTDs among sibs of children with major malformations such as tracheo-esophageal "dysraphism," cleft lip/palate, or renal agenesis. NTDs are apparently etiologically heterogeneous.

Anencephaly↗
PubMed2003

Is there more to folates than neural-tube defects?

The purpose of the present paper is to review our current understanding of the chemistry and biochemistry of folic acid and related folates, and to discuss their impact on public health beyond that already established in relation to neural-tube defects. Our understanding of the fascinating world of folates and C1 metabolism, and their role in health and disease, has come a long way since the discovery of the B-vitamin folic acid by Wills (1931), and its first isolation by Mitchell et al. (1941). However, there is still much to do in perfecting methods for the measurement of folate bioavailability, and status, with a high extent of precision and accuracy. Currently, examination of the relationships between common gene polymorphisms involved in C1 metabolism and folate bioavailability and folate status, morbidity, mortality and longevity is evaluated as a series of individual associations. However, in the future, examination of the concurrent effects of such common gene polymorphisms may be more beneficial.

Ascorbic Acid↗
PubMed2002

Folic acid intake and its effects on the prevention of neural tube defects, the masking of vitamin B12 deficiency and the reduction of homocysteine.

The FDA's decision to require the fortification of the United State's grain supply with folic acid was made complex by proponents' arguments for its protective properties against neural tube defects (NTD) vs. opponents' concern regarding safety-risks in masking vitamin B12 deficiency in the elderly. Since this regulation mandated an effective date of January 1, 1998, research has been conducted to identify the impact that the fortification of 140 micrograms/100 g of grain in the U.S. grain supply has had on public health. Studies attempted to more accurately describe the minimum effective dose for prevention of NTD and to identify the levels at which it presents a health risk. Several studies have been reviewed and recommendations have been provided for altering the level of folic acid fortification.

Female↗
PubMed2003

Frequency of Down's syndrome and neural-tube defects in the same family.

BACKGROUND: There is evidence that some mothers of infants with Down's syndrome have abnormal metabolism of folate and methyl, as well as mutations in folate genes, which are features that are also seen in neural-tube defects (NTD). We therefore investigated whether Down's syndrome and NTD arise more often in the same family than would be expected from the incidence of each disorder considered separately. METHODS: We studied two series of families using information obtained from medical records about maternal age, pregnancy outcome, congenital malformations, and karyotype: the first, 493 families from Israel who were at high risk of NTD (445 with a history of NTD and 48 with isolated hydrocephalus); and the second, 516 families from the Ukraine at high risk of Down's syndrome. FINDINGS: In the families at risk of NTD, there were a total of 11 pregnancies affected by Down's syndrome in 1492 at-risk pregnancies (compared with 1.87 expected on the basis of maternal age), which was a significant increase (p<0.00001). In the families at risk of Down's syndrome, there were seven NTD pregnancies in 1847 at risk, compared with 1.37 expected (p<0.001). INTERPRETATION: In this study, we provide direct evidence of a link between Down's syndrome and NTD. Folate supplementation before conception has the potential to reduce the frequency of Down's syndrome.

Adult↗
PubMed1992

Dual Analyte immunoassay--a new approach to neural tube defect and Down's syndrome screening.

A microtiter plate based Dual Analyte enzyme-immunoassay method for the simultaneous measurement of alpha-fetoprotein (AFP) and Free-beta human chorionic gonadotrophin (hCG) was evaluated. This rapid assay, which has application in both Neural Tube Defect screening and Down's screening, shows good precision with between assay coefficients of variation between 5 and 7.5% for AFP and 3.7 to 5.8% for Free-beta(hCG). Correlation with single analyte procedures is good, with correlation coefficients being greater than 0.91 in both cases. Clinical discrimination in detecting both types of abnormalities is not compromised by this new simultaneous Dual Analyte assay. We conclude that the Dual Analyte approach, which combines analytes achieving the highest known detection efficiency, will bring about improvements in the efficiency of screening, reduce costs and improve report turnaround, all leading to better quality of patient care.

Chorionic Gonadotropin↗
PubMed1987

A cohort study of neural tube defects (NTD) in Denmark covering the first seven years of life.

In the County of Fyn, Denmark, which is a well-delimited region comprising a 10% representative sample of the total population, ten complete one year cohorts of newborn were scrutinized for neural tube defects (NTD). Among 66,000 births, 71 cases with NTD were observed. The total prevalence at birth was 1.08/1,000; 0.29 for anencephaly; 0.20 for encephalocele, and 0.59 for spina bifida (SB). This is at the same level as in other Scandinavian countries. Considering only neonates born alive, 57% of the total survived until the age of 7 years, disregarding anencephaly, but only 4 of 18 SB cases and 6 of 11 encephalocele cases had no handicaps at age 7. On the average, SB patients spent 9% of their life before the age of 7 years in hospitals and encephaloceles 2%. The SB cases occupied 25 times more beds per year than the comparable age group in general and many were likely to need continued medical and social care.

Anencephaly↗