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PubMed2006

Exposure to fumonisins and the occurrence of neural tube defects along the Texas-Mexico border.

Along the Texas-Mexico border, the prevalence of neural tube defects (NTDs) among Mexican-American women doubled during 1990-1991. The human outbreak began during the same crop year as epizootics attributed to exposure to fumonisin, a mycotoxin that often contaminates corn. Because Mexican Americans in Texas consume large quantities of corn, primarily in the form of tortillas, they may be exposed to high levels of fumonisins. We examined whether or not maternal exposure to fumonisins increases the risk of NTDs in offspring using a population-based case-control study. We estimated fumonisin exposure from a postpartum sphinganine:sphingosine (sa:so) ratio, a biomarker for fumonisin exposure measured in maternal serum, and from maternal recall of periconceptional corn tortilla intake. After adjusting for confounders, moderate (301-400) compared with low (< or = 100) consumption of tortillas during the first trimester was associated with increased odds ratios (ORs) of having an NTD-affected pregnancy (OR = 2.4; 95% confidence interval, 1.1-5.3). No increased risks were observed at intakes higher than 400 tortillas (OR = 0.8 for 401-800, OR = 1.0 for > 800). Based on the postpartum sa:so ratio, increasing levels of fumonisin exposure were associated with increasing ORs for NTD occurrences, except for the highest exposure category (sa:so > 0.35). Our findings suggest that fumonisin exposure increases the risk of NTD, proportionate to dose, up to a threshold level, at which point fetal death may be more likely to occur. These results also call for population studies that can more directly measure individual fumonisin intakes and assess effects on the developing embryo.

Adolescent↗
PubMed2002

Potential prevention of neural tube defects by assessment of women of childbearing age through monitoring of folate.

BACKGROUND: Three quarters of neural tube defects (NTD) can be prevented by sufficient dietary folate supplementation. Despite this knowledge, most women do not supplement their diet effectively. Red cell folate concentrations correlate with the risk of NTD, and levels of less than 900 nM are associated with an increased risk of these serious congenital anomalies. OBJECTIVE: Laboratory tests to assess anemia include testing for folate. This study was conducted to estimate the potential benefits of informing women of reproductive age who are unaware of their low folate levels, uncovered in their anemia tests. METHODS: The number of Ontario women of reproductive age who undergo folate tests and are at an increased risk of NTD was calculated. In addition, the authors calculated the number of NTD cases that could have been prevented if these women were informed of the possible consequences of their low folate levels should they become pregnant. RESULTS: In 1998, red cell folate concentrations were measured in 23,109 women of childbearing age (15-45 y). Approximately half of the women [n = 11,392 (49.3%)] had folate levels below 900 nM and thus were at an increased risk of giving birth to a child with NTD should they have become pregnant. Their overall mean relative risk (RR) of NTD was 1.95, or 1:512 births. If they would have been informed of this risk and subsequently increased their consumption of folate before becoming pregnant, 22.3 cases of NTD per year could have possibly been prevented at no extra cost, since the folic acid results were a part of investigational blood tests performed for another reason (anemia). CONCLUSIONS: Women of reproductive age who are being evaluated for the cause of anemia and have low red cell folate results constitute a high-risk group for NTD in their children. These women should be informed of the increased risk and of methods of dietary folate supplementation.

Adolescent↗
PubMed2005

Prenatal screening for Down syndrome and neural tube defects in twin pregnancies.

Prenatal screening and diagnosis in a twin pregnancy is not straightforward. Once a twin pregnancy has been identified, women and their partners need time to consider the implications and decide whether they wish the pregnancy to be screened for Down syndrome or neural tube defects. We discuss here how multiple marker screening for Down syndrome and alpha-fetoprotein screening for neural tube defects can be carried out, given that this is the parents' chosen option and that the health professionals involved are capable of performing a diagnosis and selective feticide, should this arise.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMedDate not supplied

Spina bifida and other neural tube defects.

NTDs, resulting from failure of the neural tube to close during the fourth week of embryogenesis, are the most common severely disabling birth defects in the United States, with a frequency of approximately 1 of every 2000 births. Neural tube malformations involving the spinal cord and vertebral arches are referred to as spina bifida, with severe types of spina bifida involving protrusion of the spinal cord and/or meninges through a defect in the vertebral arch. Depending on the level of the lesion, interruption of the spinal cord at the site of the spina bifida defect causes paralysis of the legs, incontinence of urine and feces, anesthesia of the skin, and abnormalities of the hips, knees, and feet. Two additional abnormalities often seen in children with spina bifida include hydrocephalus and the Arnold-Chiari type II malformation. Despite the physical and particular learning disabilities children with spina bifida must cope with, participation in individualized educational programs can allow these children to develop skills necessary for autonomy in adulthood. Advances in research to uncover the molecular basis of NTDs is enhanced by knowledge of the link between both the environmental and genetic factors involved in the etiology of NTDs. The most recent development in NTD research for disease-causing genes is the discovery of a genetic link to the most well-known environmental cause of neural tube malformation, folate deficiency in pregnant women. Nearly a decade ago, periconceptional folic acid supplementation was proven to decrease both the recurrence and occurrence of NTDs. The study of folate and its association with NTDs is an ongoing endeavor that has led to numerous studies of different genes involved in the folate metabolism pathway, including the most commonly studied thermolabile mutation (C677T) in the MTHFR gene. An additional focus for NTD research involves mouse models that exhibit both naturally occurring NTDs, as well as those created by experimental design. We hope the search for genes involved in the risk and/or development of NTDs will lead to the development of strategies for prevention and treatment. The most recent achievement in treatment of NTDs involves the repair of meningomyelocele through advancements in fetal surgery. Convincing experimental evidence exists that in utero repair preserves neurologic function, as well as resolving the hydrocephalus and Arnold-Chiari malformation that often accompany meningomyelocele defects. However, follow-up is needed to completely evaluate long-term neurologic function and overall improved quality of life. And in the words of Olutoye and Adzick, "until the benefits of fetal [meningomyelocele] repair are carefully elucidated, weighed against maternal and fetal risks, and compared to conventional postnatal therapy, this procedure should be restricted to a few centers that are committed (clinically and experimentally) to investigating these issues."

Animals↗
PubMed1994

Primary prevention of neural-tube defects with folic acid.

This symposium dealt with the trilogic, epidemiologic, occupational, genetic and nutritional aspects of neural tube defects (NTD). Homocysteine could be involved in the pathogenesis of NTD. Folic acid is highly recommended for prevention.

Female↗
PubMed2003

Recurrent neural tube defects associated with partial trisomy 2p22-pter: report of two siblings and review of the literature.

We report on two male siblings with partial trisomy 2p22-pter and partial monosomy 15q26-qter resulting from a maternally derived translocation t(2;15)(p22;q26). Both fetuses had different neural tube defects (craniorachischisis in the first fetus and anencephaly in the second fetus) which were detected by sonographic examination at the end of the first trimester of pregnancy. This report demonstrates the importance of chromosomal analysis in the etiologic exploration of neural tube defects and supports the importance of 2p24 triplication in neural tube development.

Anencephaly↗
PubMed2000

[Methionine synthase and neural tube defects].

It has been indicated lately that higher plasma homocysteine is one of the risk factors in neural tube defects(NTDs) and vascular disease. Methionine synthase is a key enzyme in homocysteine metabolism. The defects of methionine synthase activity could result in hyperhomocysteinemia and methionine auxotrophy. The gene mutations of methionine synthase with the epidemiological studies of NTDs are reviewed in this paper. It is considered that the gene mutations of methionine synthase can not make a relation to NTDs and hyperhomocysteine, but methionine synthase reductase may be a clue for the study on NTDs in the future.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1990

Central nervous system congenital malformations, especially neural tube defects in 29 provinces, metropolitan cities and autonomous regions of China: Chinese Birth Defects Monitoring Program.

Data from the Chinese Birth Defects Monitoring Program (CBDMP) over the period of October 1986 to September 1987 were analysed to study the descriptive epidemiology of congenital malformations of the central nervous system (CNS), especially neural tube defects (NTDs) in China. A total of 4628 CNS congenital malformations were recorded within seven days of delivery among 1,243,284 live and stillbirths of 28 or more weeks gestation in 945 hospitals from all 29 provinces, metropolitan cities and autonomous regions of China. Neural tube defects account for 73.55% of these cases, hydrocephaly for 24.63% and microcephaly for 1.82%. The prevalence rates at birth of NTDs and congenital malformations of the CNS in China were 27.37 and 37.22 per 10,000 respectively. More NTDs were observed in females (35.68 per 10,000 female births) as compared to males (19.23 per 10,000 male births). The prevalence of NTDs in rural areas (51.69 per 10,000 births) was higher than that in urban areas (15.45 per 10,000 births).

Central Nervous System↗
PubMed1989

Neural tube defects: considerations on the pathogenesis and correlation with myelodysplasia in man. II. An experimental model.

In this second part, the authors report the results obtained by evaluating the presence of glycosaminoglycans (GAGs) in the brain of rat fetuses with neural tube defects and hydrocephalus, secondary to the administration of trypan blue during pregnancy. A decrease in the GAG content was found. The authors hypothesize that this anomaly in GAG formation is responsible for both the neural tube defect and the associated malformations, namely hydrocephalus and hypoplasia of the posterior cranial fossa.

Animals↗
PubMed1985

The apparently declining prevalence of neural tube defect in two counties in South Wales over three decades illustrating the need for continuing action and vigilance.

Neural tube defects, anencephaly and spina bifida (including encephalocele) have been the major malformation problem in South Wales. Births of affected offspring of residents of Mid and South Glamorgan between 1956 and June 1985 were ascertained from various sources. To these were added terminations following prenatal diagnosis and affected spontaneous abortions of 16 weeks gestation or more since 1973. Variable fluctuation in prevalence occurred between 1956 and 1965. Since then there has been an accelerating decline in the birth prevalence of NTD but especially of anencephaly in both counties. When abortions and terminations are taken into consideration the decline until 1984, though still present, is much slower and is virtually non-existent now. The need for continuing NTD pregnancy screening and prenatal diagnosis followed by selective abortion is stressed. It is suggested that genetic counselling health education to improve maternal nutrition preconceptional counselling and population folic acid supplementation should be extended to prevent these defects.

Abortion, Therapeutic↗
PubMed2004

Florida health care providers' knowledge of folic acid for the prevention of neural tube defects.

OBJECTIVES: The purpose of this study was to determine the impact of an educational program on the knowledge and practice behavior of health care providers regarding folic acid use for the prevention of neural tube defects. METHODS: A survey was mailed to selected Florida health care providers to determine baseline knowledge and practice behavior. After a statewide educational program, another mail survey was sent to the same groups of providers to determine the effect of the campaign. RESULTS: Comparison between the two surveys showed a significant increase in knowledge and in the percentage of health care providers who recommended the periconceptional use of folic acid for the prevention of neural tube defects. Providers graduating in 1992 or later were more likely than those graduating before 1992 to have the appropriate knowledge about folic acid use but were less likely to recommend it to their patients. CONCLUSIONS: Significant gains were made in increasing knowledge and changing practice behavior among selected Florida health care providers. Regardless of the magnitude of these gains, our data show that some health care providers who have regular contact with women of childbearing age still do not know the recommended doses of folic acid or do not recommend its use. This points toward the need for continued education as well as efforts to modify provider behavior.

Adult↗
PubMed2001

Maternal exposure to nitrate from drinking water and diet and risk for neural tube defects.

In this population-based case-control study conducted in California between June 1989 and May 1991, the authors investigated the association between maternal periconceptional exposure to nitrate from drinking water and diet and risk for neural tube defects. The mothers of 538 cases and 539 nonmalformed controls were interviewed regarding residential history, consumption of tap water at home, and dietary intake during the periconceptional period. Dietary nitrate exposure was not associated with increased risk for neural tube defects. Exposure to nitrate in drinking water at concentrations above the 45 mg/liter maximum contaminant level was associated with increased risk for anencephaly (odds ratio (OR) = 4.0, 95% confidence interval (CI): 1.0, 15.4), but not for spina bifida. Increased risks for anencephaly were observed at nitrate levels below the maximum contaminant level among groundwater drinkers only (OR = 2.1, 95% CI: 1.1,4.1 for 5-15 mg/liter; OR = 2.3, 95% CI: 1.1, 4.5 for 16-35 mg/liter; and OR = 6.9, 95% CI: 1.9, 24.9 for 36-67 mg/liter compared with <5 mg/liter). Adjustment for identified risk factors for anencephaly did not substantially alter these associations, nor did control for maternal dietary nitrate, total vitamin C intake, and quantity of tap water consumed. The lack of an observed elevation in risk for anencephaly in association with exposure to mixed water containing nitrate at levels comparable with the concentration in groundwater may indicate that something other than nitrate accounts for these findings.

Adolescent↗
PubMed1995

Impact of prenatal diagnosis on the birth prevalence of neural tube defects, Atlanta, 1990-1991.

OBJECTIVE: To determine the impact of prenatal diagnosis on the birth prevalence of neural tube defects (NTDs) in Atlanta during 1990 through 1991. METHODS: Live-born and stillborn infants with NTDs who were at least 20 weeks' gestation were ascertained by the Metropolitan Atlanta Congenital Defects Program (MACDP), a population-based birth defects registry. Prenatally diagnosed NTD-affected pregnancies were ascertained from the four perinatal centers and the three genetic laboratories operating in Atlanta during 1990 through 1991. Fetal death certificates were also reviewed for potential cases. RESULTS: During 1990 through 1991, MACDP ascertained 59 NTD cases, for a birth prevalence of 0.77/1000 live births. During this period, an additional 28 NTD-affected pregnancies were detected prenatally and terminated before 20 weeks' gestation. The adjusted NTD rate during 1990 through 1991, which includes prenatally diagnosed cases, was 1.13/1000 live births. CONCLUSIONS: Prenatal diagnosis is making a substantial impact on the birth prevalence of NTDs in Atlanta. However, since NTD rates in Atlanta were 2 to 2.5 per 1000 live births in 1970, prenatal diagnosis and termination of pregnancy does not completely account for the declining rate of NTDs.

Abortion, Induced↗
PubMed1984

Hyperzincemia in anencephaly and spina bifida: a clue to the pathogenesis of neural tube defects?

Zinc is essential for normal embryogenesis and may have particular importance for closure of the human neural tube. Compared to 258 controls, we found increased zinc content in umbilical cord serum in eight of nine newborn anencephalics (p less than 0.02) and three infants with spina bifida (p less than 0.001). Increased zinc levels were bound to serum albumin or alpha-2-macroglobulin (alpha 2M) in infants with neural tube defects (NTD). In NTD-mothers, total serum zinc was similar to controls, but there was a shift in the distribution of zinc from alpha 2M to albumin. Fetal hyperzincemia and elevated maternal albumin-bound zinc suggest that the NTD-fetus receives but does not use zinc normally.

Adult↗
PubMed2006

Recent advances on neural tube defects with special reference to Valproic Acid.

Epilepsy is a common medical problem and many studies have demonstrated that infants of women with epilepsy (WWE) have a two to threefold higher risk of congenital malformations compared with the background population. The majority of WWE have normal, healthy children. However, WWE have an increased risk of congenital malformations. Congenital malformations are twice as common in infants exposed to antiepileptic drugs in utero. A variety of congenital malformations have been reported, with a particular preponderance of orofacial clefts. Valproate is often associated with the development of neural tube defects. In this review, we analyse the problem of neural tube defects and report in detail the main pathogenetic theories about the onset of this type of congenital malformation. There is strong evidence for a protective effect of adequate folate consumption.

Adult↗
PubMed2000

A genetic risk factor for mouse neural tube defects: defining the embryonic basis.

Genetic polymorphisms are thought to play an important role in determining susceptibility to neural tube defects (NTDs), for example between different ethnic groups, but the embryonic manifestation of these polymorphic genetic influences is unclear. We have used a mouse model to test experimentally whether polymorphic variations in the pattern of cranial neural tube closure can influence susceptibility to NTDs. The site at which cranial neural tube closure begins (so-called closure 2) is polymorphic between inbred mice. Strains with a caudal location of closure 2 (e.g. DBA/2) are relatively resistant to NTDs, whereas strains with a rostrally positioned closure 2 (e.g. NZW) exhibit increased susceptibility to NTDs. We tested experimentally whether altering the position of closure 2 can affect susceptibility to cranial NTDs, by back- crossing the splotch ( Sp (2H) ) mutant gene onto the DBA/2 background. As a control, Sp (2H) was transferred onto the NZW background, which resembles splotch mice in its closure pattern. Approximately 80% of Sp (2H) homozygotes develop NTDs, both cranial (exencephaly) and spinal (spina bifida). After transfer to the DBA/2 background, the frequency of cranial NTDs was reduced significantly in Sp (2H) homozygotes, confirming a protective effect of caudal closure 2. In contrast, Sp (2H) homozygotes on the NZW background had a persistently high frequency of cranial NTDs. The frequency of spina bifida was not altered in either backcross, emphasizing the specificity of this genetic effect for cranial neurulation. These findings demonstrate that variation in the pattern of cranial neural tube closure is a genetically determined factor influencing susceptibility to cranial NTDs.

Animals↗
PubMed2002

Dietary folate and the incidence and prevention of neural tube defects: a proposed triple intervention approach in Israel.

The efficacy of folic acid in the prevention of neural tube defects depends on whether it is administered to women during the period surrounding conception. Optimizing the compliance of women at this critical time is a public health challenge. We assess the need for formulation of public health policy in Israel aimed at enhancing folate intake by women, examine policy implementation strategies, and review policy options regarding the approaches to enhance folic acid intake.

Adult↗
PubMed1994

Prevalence of neural tube defects in Cape Town, South Africa.

The aim of the study was to document the frequency of neural tube defects (NTD) over a 20-year period in Cape Town and to determine the effects of race, gender, maternal age, parity and season of conception on the prevalence. Multiple sources of ascertainment were used, including all maternity hospital records, neurosurgical and spinal defects clinic data, as well as those from the Human Genetics Department and Fetal Abnormality Group. The prevalence rates for NTD fluctuated between 1.74 and 0.63 per 1,000 births, but showed no significant trends over the 20-year period. Prevalence rates were highest for the white population group of 2.56 per 1,000 births compared to 0.95 per 1,000 for blacks and 1.05 per 1,000 for those of mixed ancestry. The higher rates in the whites, who are of British and European extraction and belong to the more affluent section of the community, would suggest that the possible effects of nutrition and infection are overshadowed by genetic factors. There was a female preponderance for both spinal bifida (M:F ratio 0.89) and anencephaly (M:F ratio 0.67). The highest NTD rates were found at both ends of the maternal age range (< 20 years and > 35 years of age). The prevalence was highest at the extremes of birth order (1.65 and 1.58 for birth order 1 and > 7, respectively, and 0.56 and 0.45 for birth order 5 and 6, respectively). A seasonal variation occurred which differed from that reported for the Northern Hemisphere and may reflect local climatic conditions.

Adult↗