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PubMed1996

Neural tube defects and deletions of 22q11.

Recently we reported on three unrelated children with neural tube defects (NTDs) and deletion of 22q11. Two of these children have velo-cardio-facial syndrome and the third DiGeorge sequence. Thus, NTDs appear to be part of the clinical picture due to 22q11 deletion. To further explore this association and to clarify what findings should prompt testing for this deletion in individuals with NTDs, we have reviewed all patients in a large regional spina bifida clinic population. Two hundred ninety-five patients with NTDs were identified by chart review. Charts were reviewed for congenital heart defect, minor facial anomalies, thymic hypoplasia, cleft lip and/or palate, hypocalcemia, and a family history of a NTD, congenital heart defect, or cleft lip and/or palate. A total of 22 patients was identified with NTD and at least one more clinical trait and/or a positive family history. Sixteen children received cytogenetic and molecular testing including the three previously reported patients diagnosed with a 22q11 deletion. Results of cytogenetic and molecular studies of the remaining 13 patients were normal. Deletion of 22q11 is an infrequent cause of NTDs. We recommend testing for the 22q11 deletion in patients with a NTD and conotruncal heart defect. Testing should be considered in patients with a NTD who have a first degree relative with a conotruncal heart defect or have additional clinical findings of VCFS or DGS.

Child↗
PubMedDate not supplied

Latex allergy: the incidence among Turkish children with atopic disease and with neural tube defects.

BACKGROUND: latex allergy occurs mainly in people exposed to latex products because of their occupation or because of repeated surgery. Atopy is a strong predisposing factor. Identification of latex sensitive individuals can be life saving. METHODS: to investigate the incidence of latex hypersensitivity, 212 children with atopic disease, 85 with neural tube defects and 200 normal children aged 2 to 14 years were interviewed and prick skin tests were performed. RESULTS: latex allergy was found in 10.8% of atopic children, 30.5% of children with neural tube defects, and 1% of normal children. Latex allergy incidence in operated children with neural tube defects was found 3.5 times more frequently in compare with non-operated patients. CONCLUSIONS: atopic children and children with neural tube defects should carefully be followed up for latex allergy specially if recurring itching, urticaria, eczema, rhinitis and eye symptoms are present.

Adolescent↗
PubMed1976

Prenatal diagnosis of neural tube defects.

A prospective program for the prenatal detection of neural tube defects in a high-risk pregnancy group has been under way for one year. Twenty high-risk mothers have undergone a complete prenatal work-up, including sonography, amniocentesis, and amniotic fluid and maternal serum alpha-fetoprotein quantitation. Within this group, two cases were prospectively diagnosed and were later confirmed.

Abortion, Induced↗
PubMed1987

The pattern of congenital renal anomalies associated with neural-tube defects.

This is a retrospective study of 190 patients with neural-tube defects for whom there were precise data, both on sensory levels (to pin-prick) and on the presence or absence of congenital renal anomalies. There were 17 renal anomalies, of which three were renal agenesis, five horseshoe kidneys, eight ureteral duplications and one simple ureterocele. There was a consistent pattern of congenital renal anomalies in relation to the extent of the neurological lesion, as measured by the sensory level. Renal agenesis was associated with a sensory level in the dermatomes T5 to T8, horseshoe kidneys with a T9 to L1 level and ureteral duplications predominantly with a sensory level in the sacral dermatomes.

Abnormalities, Multiple↗
PubMed1983

Prenatal diagnosis of neural tube defects using the cholinesterases.

The usefulness of a cholinesterase assay and electrophoresis in the prenatal diagnosis of neural tube defects was investigated in amniotic fluids from 1,512 women. The assay used a alpha-naphthyl acetate as substrate and measured the combined activity of the enzymes acetylcholinesterase (AChE, E.C. 3.1.1.7) and cholinesterase (ChE, E.C. 3.1.1.8); the activity of both enzymes was raised in amniotic fluid from women carrying open NTDs. The alpha-naphthyl acetate assay distinguished fetuses with neural tube defects from normal fetuses more effectively than assays using acetylthiocholine as substate. A perfect score could be obtained on the sample tested when both enzyme assay and electrophoresis were done on those samples with activity greater than or equal to 4 mU. There was no correlation between gestational age between 13-21 weeks and activity of AChE + ChE (r = 0.03). The electrophoretic band of AChE activity proved to be a valuable diagnostic adjunct to both AFP or the AChE + ChE assay. A similar band or AChE activity was seen in adult brain and intestine but not in kidney, heart, liver, or lung, or in sera from women carrying normal or NTD fetuses.

Amniotic Fluid↗
PubMedDate not supplied

Neural tube defects in the offspring of thalassemia carriers.

OBJECTIVES: The risk of neural tube defects (NTDs) is negatively correlated with maternal folate levels in early pregnancy. Thalassemia carriers often have reduced red cell folate contents. The aim of this study was to verify whether thalassemia carriers are at increased risk of having offspring with a NTD. METHODS: We retrospectively evaluated the prevalence of thalassemia carriers among 75 women who had prenatal diagnoses of NTDs made at our center. RESULTS: The prevalence of beta-thalassemia carriers among the affected pregnancies was significantly higher than in the general population (22.5 versus 14%, p < 0.05, chi(2) test). CONCLUSION: Although inconclusive, these data indicate that folate supplementation is mandatory among women with thalassemia who are planning a pregnancy.

Female↗
PubMed1996

Folate intake in young women and their knowledge of preconceptional folate supplementation to prevent neural tube defects.

OBJECTIVES: To ascertain knowledge of periconceptional folate for prevention of neural tube defect (NTD) and to estimate folate intake in young women. STUDY DESIGN: Three hundred young women were questioned about their knowledge of folate for prevention of NTD. Their folate intake was assessed by food frequency questionnaire. RESULTS: Fourteen per cent of 16-19 year olds and 41% of undergraduates were aware of the need to increase folate intake before conception. Median folate intake was estimated to be 235 micrograms/d in 16-19 year olds and 248.5 micrograms/d in undergraduates. More than a quarter of women in both groups had folate intakes less than the reference nutrient intake (RNI) (200 micrograms/d) below which prevalence of NTD rises dramatically and these women would therefore be at increased risk of having a child with NTD should they have an unplanned pregnancy. CONCLUSIONS: Strategies are required to increase folate intake among young women and inform them of the benefit of peri-conceptional folate supplementation.

Adolescent↗
PubMedDate not supplied

Antisense modulation of 5,10-methylenetetrahydrofolate reductase expression produces neural tube defects in mouse embryos.

The role of folate metabolism in producing neural tube defects (NTDs) in humans is unknown. In the current study, antisense oligodeoxyribonucleotide technology was utilized to disrupt normal expression of the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) in organogenesis-stage mouse embryos. Two different antisense probes were microinjected into the amniotic sac of gestation day (GD) 8 mouse embryos with PBS or scrambled sense oligodeoxyribonucleotides injected into control embryos. Concentration-dependent increases in the frequencies of embryos with NTDs were observed for both antisense sequences. The level of mRNA for MTHFR was decreased in embryos treated with the higher concentration of one antisense sequence, indicating that the sequence is able to decrease gene expression. 5-methyltetrahydrofolate, the product of the MTHFR reaction, was able to decrease the incidence of antisense-induced NTDs, but co-injection with L-methionine did not. These results suggest that reduced expression of MTHFR may play a role in producing NTDs.

Animals↗
PubMed1996

Neural tube defects 1974-94--down but not out.

AIMS: To describe accurately the total prevalence of neural tube defects (NTDs) in England and Wales over time, and to provide a benchmark up to 1994. METHODS: National data about NTDs reported as births or terminations are available from 1974-94, but reporting is incomplete. A local register of NTDs covering Oxfordshire/west Berkshire from 1965-94 was used to validate national data for the locality, using the method of capture and recapture, and hence to estimate incompleteness of reporting nationally. RESULTS: National underreporting is consistent at about two thirds of the true number of cases reaching at least the second trimester. The local register is much more complete, but time trends locally and nationally are similar. In England and Wales total prevalence declined from about 34 per 10000 live and stillbirths in 1974 to a plateau of just under 8 per 10000 in the 1990s. CONCLUSIONS: The decline in NTD prevalence is real and seems to have stopped. How this relates to changes in diet or the practice of vitamin supplementation is unknown, and the implications of the plateau are uncertain. OPCS figures of 500 NTDs annually in England and Wales represent about two thirds of the true number of cases.

England↗
PubMed2003

Genetic dissection of hyperthermia-induced neural tube defects in mice.

BACKGROUND: Maternal hyperthermia has been shown to induce neural tube defects (NTD) in humans and in experimental animal systems. We report the first genetic dissection of maternal hyperthermia-induced NTD in mice. METHODS: After maternal exposure on E8.5 to 43 degrees C water bath for 10 min, we observed exencephaly frequencies among E15.5-17.5 fetuses from the following crosses and backcrosses, SWV/Fnn(SWV)xSWV, C57BL/6J(C57)xC57, SWVxC57 (F1), F1xSWV and SWVxF1. RESULTS: The fetuses with maternal hyperthermia exposure developed exencephaly in a strain-dependent manner and the exencephaly frequencies among the above crosses were 46.2, 14.3, 13.6, 11.3, and 27.0%, respectively, expressed over total live fetuses. The fetal death rates were 47.3, 24.6, 37.1, 4.3, and 35.5%, respectively, expressed over total implants. CONCLUSION: The data demonstrate that a single fetal genetic locus, plus a maternal effect, have likely caused the strain differences in the susceptibility to hyperthermia-induced exencephaly. A maternal effect alone may have caused the higher prenatal mortality rates in the SWVxF1 cross versus the reciprocal cross. Analysis of gender ratios among those affected from these crosses excludes an X- or Y-linked effect in causing the higher numbers of affected females.

Animals↗
PubMedDate not supplied

Trends in periconceptional folic acid use by relatives in Irish families with neural tube defects.

Close relatives in families who have a child with a neural tube defect (NTD) are at greatly increased risk of having an affected child. Periconceptional folic acid reduces the risk of both occurrence and recurrence of NTDs substantially. Public health authorities currently recommend that the diets of all women between the ages of 15 and 44 who are capable of becoming pregnant be supplemented with folic acid tablets daily. We wondered if relatives in NTD families were more likely to use folic acid. From data obtained by interview with uncles and aunts in Irish NTD families we evaluated folic acid use in 144 of their pregnancies occurring between 1990 and 2000. There was a significant trend towards increasing use of folic acid both before and during pregnancy over the 10 years covered by the study. During the most recent years, 1998-2000, 57.9% of pregnancies reported by aunts were supplemented beforehand and 89.5% during the pregnancy. Pregnancies to smokers were significantly less likely to be supplemented with folic acid. In this study close relatives of an NTD child were more likely to report periconceptional folic acid use than the general public. While these results are encouraging, more remains to be done to ensure in this high risk group to ensure that the full prevention potential of folic acid is realised.

Dietary Supplements↗
PubMed2002

Physical activity and risk of neural tube defects.

OBJECTIVE: Owing to its association with known risk factors for neural tube defects (NTDs) and its impact on physiologic processes relevant to fetal development, physical activity was identified as a potential risk factor for NTD-affected pregnancy. METHODS: Using data from a population-based case-control study of deliveries occurring in California from 1989 to 1991, we estimated the potential risk of having an NTD-affected pregnancy associated with variation in maternal physical activity. In-person interviews were conducted with 538 (88% of eligible) mothers of NTD cases and with mothers of 539 (88%) nonmalformed controls on average 5 months from the term delivery date. An index reflecting reported frequency and exertion level for six activity groups (e.g., jogging and running) was used to summarize each woman's physical activity level in the periconceptional period. RESULTS: Unadjusted analyses indicated that compared to women considered inactive by this index, physically active women had 30-50% lower risk for NTD-affected pregnancies. After adjustment for several potential confounders and an evaluation of potential effect modification, results suggested that the association was restricted to women who did not take multivitamin/mineral supplements during the periconceptional period. Excluding mothers with reported medical problems did not substantially alter findings. CONCLUSIONS: This study suggests that the benefits of physical activity may extend to reduction of NTD risk among certain subgroups of women.

California↗
PubMed2000

Folate pathway gene alterations in patients with neural tube defects.

Periconceptional folate supplementation reduces the recurrence and occurrence risk of neural tube defects (NTD) by as much as 70%, yet the protective mechanism remains unknown. Inborn errors of folate and homocysteine metabolism may be involved in the aetiology of NTDs. Previous studies have demonstrated that both homozygosity for the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, and combined heterozygosity for the C677T and for another mutation in the same gene, the A1298C polymorphism, represent genetic risk factors for NTDs. In an attempt to identify additional folate related genes that contribute to NTD pathogenesis, we performed molecular genetic analysis of folate receptors (FRs). We identified 4 unrelated patients out of 50 with de novo insertions of pseudogene (PS)-specific mutations in exon 7 and 3'UTR of the FRalpha gene, arising by microconversion events. All of the substitutions affect the carboxy-terminal amino acid membrane tail, or the GPI anchor region of the nascent protein. Furthermore, among 150 control individuals, we also identified one infant with a gene conversion event within the FRalpha coding region. This study, though preliminary, provides the first genetic association between molecular variations of the FRalpha gene and NTDs and suggests that this gene can act as a risk factor for human NTD.

3' Untranslated Regions↗
PubMed2004

Metabolic effects and the methylenetetrahydrofolate reductase (MTHFR) polymorphism associated with neural tube defects in southern Brazil.

BACKGROUND: The importance of metabolic factors in neural tube defects (NTDs) has been the focus of many investigations. Several authors have suggested that abnormalities in homocysteine metabolism, such as hyperhomocysteinemia, folate deficiency, and low vitamin B12, may be responsible for these malformations and that both nutritional factors and genetic abnormalities are associated with them. METHODS: We conducted a case-control study to investigate the influence of biochemical and genetic factors in NTDs in infants in southern Brazil. Levels of folate, vitamin B12, total homocysteine (t-Hcy) and the 677C>T and 1298A>C polymorphisms of the MTHFR gene were analyzed in 41 NTD child-mother pairs and 44 normal child-mother control pairs. RESULTS: Subjects in the case group had a higher mean blood folate level than those in the control group. The level of vitamin B12 was lower in mothers in the NTD group than in control mothers (p = 0.004). The level of t-Hcy was not different in the two groups, but t-Hcy and vitamin B12 were correlated (p = 0.002). There was no difference in the genotype distribution for 677C>T and 1298A>C polymorphisms of MTHFR in the case and control pairs. The level of t-Hcy was correlated with 677TT. CONCLUSIONS: Despite the small sample in this study, we suggest that low vitamin B12 and, consequently, hyperhomocysteinemia are important risk factors for NTDs in our population.

Adolescent↗
PubMed2006

High-density single nucleotide polymorphism screen in a large multiplex neural tube defect family refines linkage to loci at 7p21.1-pter and 2q33.1-q35.

BACKGROUND: Neural tube defects (NTDs) are considered complex, with both genetic and environmental factors implicated. To date, no major causative genes have been identified in humans despite several investigations. The first genomewide screen in NTDs demonstrated evidence of linkage to chromosomes 7 and 10. This screen included 44 multiplex families and consisted of 402 microsatellite markers spaced approximately 10 cM apart. Further investigation of the genomic screen data identified a single large multiplex family, pedigree 8776, as primarily driving the linkage results on chromosome 7. METHODS: To investigate this family more thoroughly, a high-density single nucleotide polymorphism (SNP) screen was performed. Two-point and multipoint linkage analyses were performed using both parametric and nonparametric methods. RESULTS: For both the microsatellite and SNP markers, linkage analysis suggested the involvement of a locus or loci proximal to the telomeric regions of chromosomes 2q and 7p, with both regions generating a LOD* score of 3.0 using a nonparametric identity by descent relative sharing method. CONCLUSIONS: The regions with the strongest evidence for linkage map proximal to the telomeres on these two chromosomes. In addition to mutations and/or variants in a major gene, these loci may harbor a microdeletion and/or translocation; potentially, polygenic factors may also be involved. This single family may be promising for narrowing the search for NTD susceptibility genes.

Chromosomes, Human, Pair 2↗
PubMed2004

The effect of fever, febrile illnesses, and heat exposures on the risk of neural tube defects in a Texas-Mexico border population.

BACKGROUND: Hyperthermia produces neural tube defects (NTDs) in a variety of animal species. Elevated maternal body temperatures may also place the developing human embryo at risk. We examined the relation between maternal hyperthermia and the development of NTDs in a high-risk Mexican-American population. METHODS: Case-women were Mexican-American women with NTD-affected pregnancies who resided and delivered in any of the 14 Texas counties bordering Mexico, during 1995-2000. Control-women were randomly selected from study area residents delivering normal live births, frequency-matched to cases by hospital and year. Information on maternal fevers, febrile illnesses, exposures to heat generated from external sources, and hyperthermia-inducing activities was gathered through in-person interviews, conducted about six weeks postpartum. RESULTS: The risk effect (OR) associated with maternal fever in the first trimester, compared to no fever, was 2.9 (95% CI, 1.5-5.7). Women taking fever-reducing medications showed a lower risk effect (OR, 2.4; 95% CI, 1.0-5.6) than those who did not (OR, 3.8; 95% CI, 1.4-10.9). First-trimester maternal exposures to heat devices such as hot tubs, saunas, or electric blankets were associated with an OR of 3.6 (95% CI, 1.1-15.9). Small insignificant effects were observed for activities such as cooking in a hot kitchen (OR, 1.6; 95% CI, 1.0-2.6) and working or exercising in the sun (OR, 1.4; 95% CI, 0.9-2.2). CONCLUSIONS: Maternal hyperthermia increases the risk for NTD-affected offspring. Women intending to become pregnant should avoid intense heat exposures, carefully monitor and manage their febrile illnesses, and routinely consume folic acid supplements.

Adult↗
PubMed1981

The effect of the introduction of prenatal diagnosis on the reproductive history of women at increased risk from neural tube defects.

The reproductive history of 45 couples at increased risk for neural tube defect (NTD) who came for genetic counselling in 1970 and 1971 were compared with a similar number counselled in 1975 and 1976, when prenatal diagnostic tests were freely offered. They were subsequently interviewed in their homes and had their reproductive history recorded to the end of 1973 and 1978 respectively. Nearly all had a previous child with an NTD and none of the women were pregnant at the time of counselling. The effect of prenatal diagnosis was to speed somewhat the decision about further pregnancies, but the number of couples deciding on no further children and on having further pregnancies were almost identical in the two groups. The average number of pregnancies was 2.8 per family, with only 1.2 surviving children. The pregnancy outcomes are discussed as are the reasons for not attempting further pregnancies in both groups, which included very high risk of recurrence, a surviving spina bifida child, inability to accept the tests or its implications. Ninety per cent of the second group had tests. Their reactions to the tests were favorable but all complained of the waiting time between amniocentesis and obtaining the results. They all would have tests again in any future pregnancy. The reason for women not having prenatal diagnostic tests included inability to accept termination. It is concluded that couples in South Wales decide either to have no more children or to have further pregnancies regardless of tests, but tests speed a decision and enable the women to enjoy the pregnancy after obtaining the results, and that an NTD greatly reduces the number of children per family. A termination for an NTD is much more acceptable to most than an NTD at term. The reasons for this are discussed.

Abortion, Induced↗
PubMed1995

Elevated midtrimester serum methylmalonic acid levels as a risk factor for neural tube defects.

The role of folic acid in the primary prevention of neural tube defects (NTDs) is well established. However, questions related to the protective mechanism remain unanswered. To help answer these questions, we designed a case-control study to assess the role of folate- and cobalamin-related metabolites in the pathogenesis of NTDs. Concentrations of folate, cobalamin, and 14 other related metabolites were measured by gas chromatography/mass spectrometry in midtrimester serum specimens from 32 women with an NTD-affected pregnancy and from 132 control women, and in serum specimens from 46 nonpregnant women who had a history of NTD-affected pregnancy and from 43 nonpregnant control women. Log-transformed means of metabolites were compared between case and control women for both the midtrimester and nonpregnant groups. In the pregnant group, serum methylmalonic acid (MMA) concentrations were higher among case women than among control women (130 vs 105 nM). There was a strong dose-response relationship between midtrimester serum MMA level and the risk for an NTD-affected pregnancy, with the relative risk increasing 13-fold for women with MMA levels > 90th percentile. In the nonpregnant group, there was no difference in serum MMA levels between case and control women (140 vs 140 nM). Thus, the serum MMA levels of women in the midtrimester of pregnancies unaffected by NTDs were significantly lower than the levels of nonpregnant women, whereas the levels of women whose pregnancies were affected by NTDs were similar to those of nonpregnant women. The finding of elevated MMA serum concentrations among women in the midtrimester of NTD-affected pregnancies suggests that cobalamin may be involved in the etiology of NTDs. The possible role of cobalamin in relation to the protective effect of folic acid needs further evaluation.

Adult↗