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PubMed2004

Chromosomal abnormalities in fetuses with open neural tube defects: prenatal identification with ultrasound.

OBJECTIVES: To determine the prevalence of chromosomal abnormalities in fetuses with open neural tube defects (NTD) undergoing prenatal chromosome analysis. The role of prenatal ultrasound in detecting those with an underlying chromosomal abnormality was also investigated. METHODS: Over a 6-year period, 144 fetuses with open NTD underwent prenatal chromosome analysis between 12 and 37 weeks of gestation, as part of a prospective, multicenter prenatal diagnosis and counseling program in Chile. This population included 66 fetuses with spina bifida, 46 with acrania/anencephaly, 21 with cephalocele and 11 with iniencephaly. A confident prenatal diagnosis was made in 143 fetuses (99%) and confirmed postnatally in all cases. RESULTS: An underlying chromosomal abnormality was diagnosed in 10 fetuses (7%), six with spina bifida, three with cephalocele and one with craniorachischisis. The prevalence of chromosomal abnormality varied according to the defect present in the fetus, with a 14% (3/21) prevalence among those with cephalocele, 9% (6/66) among those with spina bifida and 2% (1/57) among those with lethal defects such as acrania, anencephaly or iniencephaly. Karyotype results revealed trisomy 18 in seven cases, trisomy 13 in two and mosaicism for a marker chromosome in one. Prenatal ultrasound before the procedure showed that all chromosomally abnormal fetuses had additional findings. The prevalence of chromosomal abnormality in fetuses with spina bifida and cephalocele was higher when chromosome analysis was performed at or before 24 weeks of gestation in comparison to those performed after 24 weeks (5/31 (16%) vs. 4/56 (7%), respectively). However, this difference did not reach statistical significance, probably due to the small number of cases. CONCLUSIONS: A significant number of fetuses with open NTD are chromosomally abnormal. Although prenatal chromosome analysis should be considered in all cases, prenatal ultrasound seems effective in identifying those fetuses with an underlying chromosomal abnormality.

Adult↗
PubMed1998

Sirenomelia with an uncommon osseous fusion associated with a neural tube defect.

A sireniform infant presented with an uncommon osseous fusion of the lower limbs characterised by a fused femur, a partially fused tibia and sympus dipus with rudimentary digits and metatarsals. Associated abnormalities included sacral agenesis, a deformed pelvis, anorectal atresia, renal agenesis, cystic renal dysplasia, agenesis of the uterus and urinary bladder, ambiguous external genitalia, a single umbilical artery, a lumbosacral neural tube defect, and ventriculomegaly secondary to a Chiari II malformation. The pathogenesis of concurrent sirenomelia and neural tube defect is discussed.

Ectromelia↗
PubMed1993

Disruption of the csk gene, encoding a negative regulator of Src family tyrosine kinases, leads to neural tube defects and embryonic lethality in mice.

All Src family non-receptor tyrosine kinases are negatively regulated by phosphorylation at a carboxy-terminal tyrosine. To analyze the significance of this regulation during development, we have generated mice deficient in Csk, a kinase that phosphorylates this tyrosine, by gene targeting in embryonic stem cells. Homozygous mutant embryos exhibit a complex phenotype that includes defects in the neural tube and die between day 9 and day 10 of gestation. Cells derived from these embryos exhibit an order of magnitude increase in activity of Src and the related Fyn kinase. Phosphorylation at the carboxy-terminal tyrosine of Src was reduced but not eliminated and was accompanied by increased phosphorylation at another key tyrosine residue. These results demonstrate that Src family kinase activity is critically dependent on phosphorylation by Csk and suggest that the regulation of kinase activity may be essential during embryogenesis.

Animals↗
PubMed1990

Primary prevention of neural tube defects with folic acid supplementation: Cuban experience.

Folic acid (5 mg) was given daily, for not less than one menstrual period before conception and until the tenth week of pregnancy, to 81 women (FS) with a history of a previous neural tube defect (NTD) birth. There was no NTD recurrence among this group or among the offspring of a further 20 women (PS) whose folic acid supplementation fell short of the full regime. In another 114 women who became pregnant without folic acid supplementation (US), there were four NTD recurrences (3.5 per cent). Our results suggest that folic acid supplementation might be an effective method of primary prevention of neural tube defects.

Administration, Oral↗
PubMed1992

Neural tube defects after infertility treatment: a review.

OBJECTIVE: To investigate whether an association exists between ovulation induction and neural tube defects (NTDs). MATERIALS AND METHODS: Risk estimations in the medical literature were identified through Medline, and validity and power were assessed. Large in vitro fertilization-embryo transfer (IVF-ET) registries represent another source of information. The total number of NTDs and the total number of fetuses were computed from five registries. These data were expressed as proportions and compared with data from the general population. RESULTS: Only one study could be identified as both valid and powerful, through literature review. This case-control study concluded there was no association between ovulation induction and NTDs. The pool of IVF-ET registry data represents another powerful epidemiologic tool. Analysis of the registry data confirms the findings of the case-control study. CONCLUSIONS: Ovulation induction does not seem to represent a risk factor for NTDs in the offspring.

Female↗
PubMed2004

Birth order and neural tube defects: a reappraisal.

There is evidence that late birth order is associated with some complex disorders. For neural tube defects (NTDs) there is no consensus as to whether first or increased birth order is associated or not. A meta-analysis of published data on NTDs was carried out to ascertain whether there is an increased risk for children first born or of high birth order to have NTDs. All data available with information regarding the frequency of live births and NTDs cases by birth order (1, 2, 3, and 4 or more) were included in the analysis. Effect sizes calculations were performed. Children with higher birth order are more likely to have spina bifida but not anencephaly. This same effect was also seen for all NTDs combined, which probably reflects the association with spina bifida. These results suggest the compilation of anencephaly and spina bifida data can be the explanation for the controversies seen in the literature.

Anencephaly↗
PubMed1995

Neural tube defects: an experimental model in the foetal rat.

We report on our experience in the experimental induction of Neural Tube Defects (NTD) in the foetal rat by maternal administration of retinoic acid. The teratogen diluted in olive oil was administered in a single intragastric dose (125 mg/kg body weight) to pregnant rats (n = 31) on the 10th day of gestation. Pure olive oil was given to control rats (n = 9). The foetuses were recovered by caesarian section on the 20th day and prepared for morphological investigation. We have studied 201 experimental and 82 control animals. There were NTD in 36.3% of experimental foetuses and none in the control ones. Sacral dysraphism was the most frequent defect but we also observed Arnold Chiari malformations and crowding of the bony limits by an enlarged neural axis. Other associated malformations found were: craneofacial (78.1%), caudal (80%), anorectal (31.4%), and limb defects (89.5%). This simple and inexpensive model may allow us to gain a better knowledge of the biology in the foetus with NTD.

Abnormalities, Drug-Induced↗
PubMed1990

Trisomy 13 syndrome and neural tube defects.

Abnormalities of the CNS, such as arhinencephaly or holoprosencephaly, are common findings in trisomy 13 syndrome. However, neural tube defects (NTDs) are rarely reported. A review of 267 patients in the literature on reported CNS developmental defects in trisomy 13 syndrome showed only 6 patients with lumbosacral NTDs. No case of encephalocele or anencephaly was found. We report on 3 patients with spina bifida from the records of 34 necropsies of karyotyped trisomy 13 syndrome, which were found among 403,710 births.

Abnormalities, Multiple↗
PubMed1992

Potential relationship between dengue fever and neural tube defects in a northern district of India.

A sudden increase in number of births of newborns with neural tube defects (NTD) was observed from June, 1989 to September, 1989 in Medical College and Hospital, Rohtak and various other government and private hospitals of the district of Rohtak. Out of a total 4785 deliveries whose records were collected, there were 87 newborns with NTD with an incidence of 18.18/1000 births which was three times higher than the previous incidence of 6.8/1000 births in the preceding 4 years. There was an epidemic of dengue fever in this area from September, 1988 to December, 1988 affecting almost one member from each family. This coincided with the period of their first trimester. Of these, 18 patients suffered clinically from dengue fever, 21 patients had positive dengue fever history in their family members, 21 patients had positive history in their neighbors. The cluster of NTD appears to be due to dengue virus infection.

Adolescent↗
PubMed1996

Impact of prenatal diagnosis and elective termination on prevalence and risk estimates of neural tube defects in California, 1989-1991.

The authors examined the impact of prenatal diagnosis and elective termination of neural tube defect (NTD)-affected pregnancies on NTD prevalence and risk estimates. Prevalence data were actively ascertained and were derived from a population-based 1989-1991 cohort of California births. Included were 664 singleton infants/fetuses with an NTD. The birth prevalence (livebirths and stillbirths only) was 48.4% of the total prevalence (including elective terminations) for anencephaly and 70.2% for spina bifida. The authors also used in-person interview data from mothers of 538 of the ascertained NTD cases and mothers of 539 randomly selected nonmalformed control infants to examine maternal/infant characteristics. Compared with women who delivered liveborn/stillborn infants with an NTD, women who electively terminated NTD-affected pregnancies were disproportionately white, were more highly educated, had higher incomes, and used vitamins containing folic acid more often. For factors associated with elective terminations, risk estimates appeared biased when only liveborn and stillborn infants were included among cases compared with analyses in which all clinically recognized NTD-affected pregnancies were included.

Abortion, Legal↗
PubMed2004

Serum lead, cadmium, and zinc levels in newborns with neural tube defects from a polluted zone in Mexico.

Serum lead, cadmium and zinc levels from 31 newborns with neural tube defects (NTD), and 54 healthy controls living in a polluted area in Mexico were estimated using atomic absorption spectrophotometry (AAS). NTD family history was found to be of greater importance in the case group (OR 6.95, 95% CI 1.51-36.3, p=0.002). In 25% of the children, serum lead concentrations were above the admissible maximum level (AML) of 10 microg/dL within 24 h of extra-uterine life. Cadmium concentrations were below the AML. Zinc deficiency was found in nine (29%) of the cases and four (9.3%) of the controls (p=0.04). The logistic regression multivariate analysis showed no correlation between NTD and high levels of any of these metals; however, a positive correlation was found to zinc deficiency (OR 5.0, 95% CI 1.07-23.00, p=0.04). These results focus attention to the surrounding nutritional and maternal health factors of major importance in disease etiology.

Cadmium↗
PubMedDate not supplied

A prospective study of amniotic fluid cholinesterases: comparison of quantitative and qualitative methods for the detection of open neural tube defects.

The value of quantitative and qualitative methods of cholinesterase (ChE) analysis in the detection of open neural tube defect (NTD) has been assessed in a prospective survey of 1495 mid-trimester amniotic fluids. Using a quantitative method the mean ChE values were much lower in fluids from pregnancies of normal outcome but it was not possible to discriminate these fluids completely from those associated with NTD pregnancies, particularly when the specimens were contaminated with blood. Similarly, measurement of acetylcholinesterase (AChE) activity alone by three different methods also failed to eliminate the overlap between the two groups. In contrast, polyacrylamide gel electrophoresis revealed only a single band of ChE activity in 1408 out of 1410 fluids from pregnancies with a normal outcome whilst amniotic fluids from all 60 cases of open NTD, 6 out of 7 cases of exomphalos and 3 out of 4 cases of intra-uterine death gave the characteristic second faster-running AChE band. A qualitative gel method which requires the same amount of ChE activity to be loaded from each amniotic fluid is an effective method for pre-natal diagnosis of NTDs.

Abortion, Induced↗
PubMed2005

Current perspectives on the causes of neural tube defects resulting from diabetic pregnancy.

Maternal diabetes increases the risk for neural tube, and other, structural defects. The mother may have either type 1 or type 2 diabetes, but the diabetes must be existing at the earliest stages of pregnancy, during which organogenesis occurs. Abnormally high glucose levels in maternal blood, which leads to increased glucose transport to the embryo, is responsible for the teratogenic effects of maternal diabetes. Consequently, expression of genes that control essential developmental processes is disturbed. In this review, some of the biochemical pathways by which excess glucose metabolism disturbs neural tube formation are discussed. Research from the author's laboratory has shown that expression of Pax3, a gene required for neural tube closure, is significantly reduced by maternal diabetes, and this is associated with significantly increased neural tube defects (NTD). Pax3 encodes a transcription factor that has recently been shown to inhibit p53-dependent apoptosis. Evidence in support of this model, in which excess glucose metabolism inhibits expression of Pax3, thereby derepressing p53-dependent apoptosis of neuroepithelium and leading to NTD will be discussed.

Animals↗
PubMed2000

[Analysis on 2158 neural tube defects diagnosed prenatally by ultrasound examination].

A retrospective survey was made to study the prenatal diagnosis on neural tube defects(NTD) by ultrasound examination from 1990 to 1993 in China. A total of 2158 livebirths and stillbirths affected by NTD with 28 weeks or more of gestation were investigated in 233 hospitals of 28 provinces, municipalities and autonomous regions all over the country. The results showed that 61.8% of the NTD were diagnosed prenatally, and 56.5% of the NTD were diagnosed by ultrasound examination. The ratios of anencephaly, myelocele and meningocele diagnosed prenatally by ultrasound examination were 66.7%, 62.5% and 52.5% respectively. Thoracic(46.4%) and lumbar (43.4%) spina bifida were diagnosed more frequently than cervical(35.5%) and sacral(31.7%) spina bifida. The ratios of prenatal diagnosis on NTD by ultrasound examination in provincial, municipal, county, and factory hospital units were 55.7%, 59.4%, 49.0% and 57.2% respectively. The ratios of prenatal diagnosis of NTD by ultrasound examination from 1990 to 1993 were 53.5%, 55.8%, 60.7% and 54.7% respectively. There was an increase in the prenatal diagnosis of NTD by ultrasound examination from 1990 to 1993. The ratios of prenatal diagnosis of NTD in county hospitals by ultrasound examination were relatively low. Anencephaly, myelocele and meningocele were more frequently diagnosed by prenatal ultrasound examination.

Adult↗
PubMed1983

Phenotypic heterogeneity in neural tube defects: a clue to causal heterogeneity.

We report here retrospective data on 991 liveborn and stillborn infants with neural tube defects (NTDs) born to Utah residents from January 1, 1940 to December 31, 1979. Data were obtained from multiple sources including approximately 1.25 million vital statistics records and several hundred physician and hospital charts. Causal heterogeneity among NTD patients is presumed because 6% of our cases have other congenital anomalies not part of the NTD field defect. A significant association of NTDs with oral clefts is noted. Sex ratios and empiric recurrence risks for isolated NTDs and NTDs associated with other major malformations are also calculated.

Abnormalities, Multiple↗
PubMedDate not supplied

Perinatal factors associated with neural tube defects (anencephaly [correction of anancephaly], spina bifida and encephalocele).

The objective of the present study was to determine the presence of risk factors for the occurrence of neural tube defects. Data for 33,535 births which occurred at Hospital do Servidor Público Estadual de São Paulo from July 1973 to December 1986 were collected in a prospective manner as recommended by "Estudo Colaborativo Latino-Americano de Malformações Congênitas" (ECLAMC, Collaborative Latin American Study on Congenital Malformations). Twenty-six cases of neural tube defects were detected (0.77/1000 births). Of these, 11 were cases of spina bifida (0.39/1000 births), 9 of anencephaly (0.27/1000 births) and 6 of encephalocele (0.18/1000 births). We observed a higher frequency of polyhydramnios, premature labor, Apgar scores of less than 7 at the first and fifth minutes, low birth weight and intrauterine growth retardation.

Anencephaly↗
PubMed1985

Heat- and alcohol-induced neural tube defects: interactions with folate in a golden hamster model.

Maternal hyperthermia or ethanol each can induce fetal neural tube defects (NTD) following exposures on the 8th day of gestation in golden hamsters. To explore the relationship between NTD and varying doses of either heat or ethanol, timed pregnant golden hamsters were exposed to various doses of either 25% ethanol, or heat in an incubator at 39.5 degrees C on the morning of the 8th day of gestation. Two doses of 0.015 ml/g body weight of 25% ethanol 4 h apart resulted in a 44% incidence of NTD when fetuses were examined on day 13. Single doses of 25% ethanol (either 0.015 or 0.0075 ml/g) resulted in very low incidences of NTD that were not significantly different from zero. A 50-min exposure to heat resulted in a 35% incidence of NTD. A shorter exposure (44 min) resulted in a 23% incidence, and a longer exposure (56 min) resulted in a 68% incidence of NTD. A 0.0075 ml/g dose of 25% ethanol, followed by these same durations of heat, resulted in incidences of NTD that were not significantly different from heat alone. In order to determine what effect folate supplementation might have on ethanol- or heat-induced NTD, osmotic pumps filled with either folate or saline were placed subcutaneously in pregnant hamsters on the 6th day of gestation. Animals were then exposed to ethanol or heat on the morning of day 8. No significant protection from NTD was evident among fetuses from mothers supplemented with folate despite significant elevations in their red cell folate levels on day 8 of gestation.

Animals↗
PubMed2000

Response of red blood cell folate to intervention: implications for folate recommendations for the prevention of neural tube defects.

Committees worldwide have set almost identical folate recommendations for the prevention of the first occurrence of neural tube defects (NTDs). We evaluate these recommendations by reviewing the results of intervention studies that examined the response of red blood cell folate to altered folate intake. Three options are suggested to achieve the extra 400 microg folic acid/d being recommended by the official committees: increased intake of folate-rich foods, dietary folic acid supplementation, and folic acid fortification of food. A significant increase in foods naturally rich in folates was shown to be a relatively ineffective means of increasing red blood cell folate status in women compared with equivalent intakes of folic acid-fortified food, presumably because the synthetic form of the vitamin is more stable and more bioavailable. Although folic acid supplements are highly effective in optimizing folate status, supplementation is not an effective strategy for the primary prevention of NTDs because of poor compliance. Thus, food fortification is seen by many as the only option likely to succeed. Mandatory folic acid fortification of grain products was introduced recently in the United States at a level projected to provide an additional mean intake of 100 microg folic acid/d, but some feel that this policy does not go far enough. A recent clinical trial predicted that the additional intake of folic acid in the United States will reduce NTDs by >20%, whereas 200 microg/d would be highly protective and is the dose also shown to be optimal in lowering plasma homocysteine, with possible benefits in preventing cardiovascular disease. Thus, an amount lower than the current target of an extra 400 microg/d may be sufficient to increase red blood cell folate to concentrations associated with the lowest risk of NTDs, but further investigation is warranted to establish the optimal amount.

Erythrocytes↗