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PubMed2004

Case for mandatory fortification of food with folate in Australia, for the prevention of neural tube defects.

BACKGROUND: Since the publication of randomized controlled trials demonstrating the prevention of neural tube defects (NTDs) with periconceptional folate, several Australian states have promoted an increase in periconceptional use of folic acid supplements. Since 1996, voluntary fortification of food with folate has been allowed in Australia and New Zealand for the purpose of preventing NTDs. METHODS: For this report, we synthesized published and unpublished data on folic acid supplement use, voluntary fortification, and trends in NTDs. RESULTS: There has been an increase in the proportion of women (up to 30-40%) taking periconceptional folic acid supplements in Australia, and many foods (mainly breakfast cereals) are fortified. Supplement use is strongly correlated with educational and socioeconomic status; consumption of voluntarily fortified foods is not. There has been a fall in NTDs of about 30% in the non-Aboriginal population, but no change has been seen in the Aboriginal population. CONCLUSIONS: These data support mandatory fortification of food as a more equitable approach to achieving sufficient folate intake in the periconceptional period for all women in Australia and New Zealand to prevent the majority of NTDs in their offspring. In May 2004, based on these and other considerations, the Australia and New Zealand Food Regulation Ministerial Council agreed that mandatory fortification of food with folate should be considered as a priority.

Australia↗
PubMed1994

Adverse effects of increased dietary folate. Relation to measures to reduce the incidence of neural tube defects.

Folate given in the periconceptional period reduced the numbers of births with neural tube defects (NTD) by 75%. Extension of these observations to all those at risk requires an increase in dietary folate, which can only be achieved by fortification of food. This will result in increased folate consumption by the whole population. Folate in excess of 1 mg daily can have adverse effects in patients with untreated cobalamin deficiency, usually undiagnosed pernicious anaemia (PA). In such patients, the anaemia is ameliorated with a return of normoblastic haemopoiesis, but in about half the patients neuropathy progresses or will develop for the first time. If continued long enough, such neuropathy is not reversed by subsequent cobalamin therapy. The lowest dose of folate that proved effective in preventing NTDs was 0.36 mg daily. This amount, added to a diet that already supplies about 0.2 mg folate, will give an average folate intake of 0.56 mg daily. To avoid exceeding this amount of folate significantly, folate should no longer be added to multivitamin preparations or the amount added should be considerably curtailed. Close surveillance should be set up to determine whether adverse effects are produced as a result of folate fortification of food. This surveillance should identify patients developing cobalamin neuropathy in the absence of anaemia and usually with a normoblastic marrow, a situation that is rare at the present time.

Anemia, Pernicious↗
PubMed1991

Genetic heterogeneity in neural tube defects.

In 1985-1987, the authors attempted to ascertain all cases of confirmed neural tube defects (NTD) in California and Illinois, not only among live-born infants (postnatal) but also cases ascertained during pregnancy (prenatal). Mothers of both prenatal and postnatal NTD cases were interviewed within 5 months. Among postnatal NTD cases, 14.9% (45/303) had anomalies not ordinarily associated with NTD. The frequency of non-NTD related anomalies was 9.4% (5/53) in anencephaly, 0/3 in craniorachischisis, 22.9% (8/35) in encephalocele, 14.5% (27/186) in spina bifida, 20% (1/5) in multiple NTD cases and 19% (4/21) in other NTDs. However, relatively few postnatal NTD cases had known multiple malformation patterns; Meckel-Gruber syndrome was the most common, with 2 postnatal cases, and 3 additional prenatal cases. Maternal age, paternal age and birth order in postnatal cases were 26.7 +/- 5.4 SD, 28.9 +/- 5.8 and 2.8 +/- 1.8, respectively. These characteristics were similar in prenatal NTD cases (27.9 +/- 6.0, 30.1 +/- 6.3, 2.5 +/- 1.5, respectively). We also found no differences in parental ages among different types of NTD. Frequency of prior spontaneous abortion differed neither between postnatal NTD (9.3%) and postnatal controls (8.1%), nor between prenatal NTD (10.7%) and prenatal control (8.7%). Loss rates in the pregnancy immediately prior to the index NTD cases were not significantly higher than in control subjects. The high frequency of non-NTD associated malformations (14.9%) indicates the caution must be exercised before assuming that a given NTD case is polygenic-multifactorial in etiology, especially cases of encephalocele.

Abnormalities, Multiple↗
PubMed2004

[Study of teratogenicity of hyperglycemia on neural tube defects and antagonistic effect of taurine].

OBJECTIVE: To explore the molecular mechanism of neural tube defects (NTDs) caused by hyperglycemia and thiadiazole and the antagonistic effect of taurine. METHODS: The pregnant mice were divided into hyperglycemia groups, thiadiazole group, taurine groups and control groups. The mRNA and the protein of Pax3 or Cx43 gene were detected respectively by reverse transcription-polymerase chain reaction assay and immunohistochemical method. RESULTS: As compared with mice treated by thiadiazole-stomach-perfusing, NTDs were significantly increased from mice treated with glucose-injection when blood glucose levels were >or= 13.4 mmol/L. Elevated glucose and thiadiazole could cause changes in Pax3 and Cx43 expression. Hyperglycemia had stronger developmental toxicity on mice embryos. Expression of Pax3 (mRNA 0.97 +/- 0.20, protein 0.11 +/- 0.02) in hyperglycemia group was significantly decreased, while expression of Cx43 (mRNA 7.05 +/- 1.63, protein 0.94 +/- 0.05) was significantly increased, and the relationship of dose-effect was demonstrated. In the thiadiazole group, the expression of Cx43 (mRNA 6.96 +/- 0.73, protein 0.92 +/- 0.12) was significantly stronger than control groups, but there were no significant differences in expression of Pax3 between thiadiazole and its control groups. Both of their teratogenicity could be antagonized by taurine. CONCLUSIONS: This study suggests that congenital malformation associated with diabetic pregnancy is caused by disruption of regulatory genes, Pax3 and Cx43 expression in embryo in response to elevated glucose. Thiadiazole can only disturb the regulation of Cx43 gene causing NTDs. Taurine can correct the disruption caused by the two teratogens.

Animals↗
PubMed1996

Effect of increasing dietary folate on red-cell folate: implications for prevention of neural tube defects.

BACKGROUND: Recommendations by the UK Department of Health suggest that protection from neural tube defects (NTD) can be achieved through intakes of an extra 400 microgram daily of folate/folic acid as natural food, foods fortified with folic acid, or supplements. The assumption is that all three routes of intervention would have equal effects on folate status. METHODS: We assessed the effectiveness of these suggested routes of intervention in optimising folate status. 62 women were recruited from the University staff and students to take part in a 3-month intervention study. Participants were randomly assigned to one of the following five groups: folic acid supplement (400 microgram/day; I); folic-acid-fortified foods (an additional 400 microgram/day; II); dietary folate (an additional 400 microgram/day; III); dietary advice (IV), and control (V). Responses to intervention were assessed as changes in red-cell folate between pre-intervention and post-intervention values. FINDINGS: 41 women completed the intervention study. Red-cell folate concentrations increased significantly over the 3 months in the groups taking folic acid supplements (group I) or food fortified with folic acid (group II) only (p<0.01 for both groups). By contrast, although aggressive intervention with dietary folate (group III) or dietary advice (group IV) significantly increased intake of food folate (p<0.001 and p<0.05, respectively), there was no significant change in folate status. INTERPRETATION: We have shown that compared with supplements and fortified food, consumption of extra folate as natural food folate is relatively ineffective at increasing folate status. We believe that advice to women to consume folate-rich foods as a means to optimise folate status is misleading.

Adolescent↗
PubMed1998

[Maternal serum screening for Down syndrome and neural tube defects].

OBJECTIVE: Evaluation of maternal serum screening for Down's syndrome (DS) and neural tube defects (NTDs). DESIGN: Longitudinal study. SETTING: Department of Obstetrics and Gynaecology, University Hospital Utrecht, the Netherlands. METHOD: 6362 pregnant women underwent serum screening for DS and (or) NTD between the 15th and 21st weeks of pregnancy between March 1991 and March 1996. Screening was performed using alpha-foetoprotein, unconjugated oestriol, human chorionic gonadotrophin and maternal age. The result of each individual test was a calculated risk for delivering a child with DS and (or) NTD. RESULTS: Nine out of 12 singleton pregnancies of a foetus with DS were detected. To this purpose, 573 women who, according to the serum screening had an increased risk of a child with the abnormality, were offered amniocentesis, which was performed in 471 of them. Two twin pregnancies with a total of 3 DS affected foetuses were also detected; one twin pregnancy of a DS foetus was screen-negative. The one case of spina bifida was screen-positive. The proportion of women eligible for invasive prenatal diagnosis because of maternal age increased from 9% to 25% in the course of the study. Of 1118 women aged > or = 36 years 913 (82%) declined invasive investigation compared with 40% in the general population. CONCLUSION: The results of the maternal serum screening program in Utrecht were comparable with other studies. Maternal serum screening is accepted as an alternative by women above 36 years, and allows to decrease the need for amniocentesis without a significant loss in detection rate.

Amniotic Fluid↗
PubMed2006

The impact of prenatal diagnosis on neural tube defect (NTD) pregnancy versus birth incidence in British Columbia.

The birth incidence of neural tube defect (NTD) cases in British Columbia (B.C.), and elsewhere in North America, is reported to be declining. This decline is being attributed to folic acid (FA) supplementation and food fortification, but 2nd trimester prenatal screening of pregnancies for NTDs and other congenital anomalies has increased during this timeframe, as well. This descriptive, population-based study evaluates the impact of prenatal screening of NTD-affected pregnancies on (1) pregnancy outcome and (2) reporting of NTD births to the provincial Health Status Registry (B.C.H.S.R.); and it assesses (3) the use of periconceptional FA supplementation. NTD cases were ascertained from medical records of health centres providing care to families with NTD-affected pregnancies and newborns; and from NTD cases reported to the B.C.H.S.R. In 1997-1999, the B.C.H.S.R. published a NTD incidence of 0.77/1000. In this study, 151 NTD-affected pregnancies were identified, with an incidence of 1.16/1000. Partial Reporting of induced abortions in a NTD incidence 45.5% low than the actual incidence. Medical records were available for review on 144/151 pregnancies. Prenatal screening identified 86.1% (124/144) of NTD-affected pregnancies, with 72.6% (90/124) resulting in pregnancy termination, and 27.4% (34/124) continuing to term. Use of FA supplementation in the periconceptional period was recorded in 36.4% of pregnancies (39/107). Thus in B.C. the decline in the NTD incidence is due predominantly to pregnancy terminations following prenatal diagnosis, which reduces the NTD incidence by 60%, from 1.16/1000 to 0.47/1000. Continued efforts for primary and the option of secondary prevention of NTDs are recommended in order to improve newborn health in B.C. and elsewhere. These interventions need to be monitored, however, for optimal health care planning.

Abortion, Eugenic↗
PubMed1997

A search for environmental and genetic background for neural tube defects: twenty-five years of experience.

The present paper illustrates the author's 25-year experience in a step by step approach to the definition of environmental and genetic background of neural tube defects. Based on the birth defects registry, a complete ascertainment of all deliveries was performed in Southern Poland during two periods: 1970-1972, and 1979-1981. The birth prevalence of neural tube defects (NTD), as well as other CNS malformations was determined. The empiric recurrence risk was calculated as 3.2% +/- 1.6. Based on this figure, the relative risk (RR = 37.6 p < 0.001) and heritability (h2 = 74.7 +/- 6.7) were estimated. Our own modification of Morton's complex segregation analysis was applied. Three Mendelian (dominant, additive and recessive) and one multifactorial model were tested. The results did not provide a clear cut discrimination between different models; however the lowest x2 value was obtained for additive inheritance with 61% of penetrance and the frequency of sporadic cases equaled 55%. A search for genetic markers did not support the hypothesis that HLA-A,B,C loci are equivalents of T/t like locus in mice. The results of the study on transcobalamine levels in amniotic fluid may suggests that different transcobalamine metabolism reflects phenotypic expression of genetic susceptibility to NTD development. Current research status and future perspectives on genetic and environmental background of NTD are also presented.

Abnormalities, Drug-Induced↗
PubMed1996

[An estimate of recurrence risk for neural tube defects in China].

A retrospective survey was made for estimating the recurrence risk of neural tube defects (NTD) in 233 hospitals of China during the period from July 1990 to June 1993. A total of 2159 women who born a baby with NTD in this pregnancy were investigated. Among them, 674 had one or more previous births (total in 889 births) before this pregnancy. Of the 889 children, 61 had NTD. Thus the overall estimate recurrence risk of NTD is 6.86%. The estimate recurrence risk of NTD is correlated with the prevalence. The estimate recurrence risks are 3.70%, 4.50% and 8.32% in the low-, average and high-prevalence areas respectively. There is a high recurrence risk for the same defect (anencephaly of spina bifida or encephalocele) of the index case.

Anencephaly↗
PubMed2003

Prenatal screening for open neural tube defects.

The era of prenatal screening for serious birth defects began in the 1970s with the discovery that amniotic fluid and maternal serum levels of alpha-fetoprotein (AFP) were increased in pregnancies affected by fetal open neural tube defects. Since then, prenatal screening has become a part of routine obstetric care. In this article, the use of AFP in prenatal screening for open neural tube defects is discussed in the context of the laboratory and the laboratory's interactions with the practicing obstetrician.

Adult↗
PubMedDate not supplied

Neural tube defects in Turkey: prevalence, distribution and risk factors.

The aim of the study was to determine the prevalence rate and risk factors relevant to neural tube defects (NTDs) in Turkey. All livebirths and stillbirths recorded at the university hospitals throughout Turkey between July 1993-June 1994 were evaluated with respect to congenital anomalies. For each birth, information was recorded about the child, the mother, the pregnancy and risk factors. A total of 66 cases with a NTD were recorded in 21,907 births. Prevalence rate of NTDs was 30.1 per 10,000 births. Of these 66 cases, 29 (43.9%) were male and 37 (56.1%) female. Female/male ratio was 1.27. The ratio of spina bifida/anencephaly is 1.20 for Turkey. Maternal illiteracy, maternal advanced age and residence in northern or eastern regions of Turkey are shown to be risk factors for having a baby with a NTD. The prevalence rate of NTDs is very high for Turkey. Geographical distribution of NTDs in this country confirms a relationship between the socioeconomic status and environmental factors for the development of a NTD. The results of this study point to the importance establishing a health policy to prevent neural tube defects in Turkey.

Adult↗
PubMed1995

Methionine overcomes neural tube defects in rat embryos cultured on sera from laminin-immunized monkeys.

Sera from laminin-immunized monkeys were previously found to cause neural tube defects in cultures of whole rat embryos by unknown mechanisms. In the present study, adding L-methionine to either the culture media or to the diets of the monkeys overcame the toxicity of the serum from one of these monkeys (LAM3) but not the other (LAM4). The antilaminin antibody levels and avidities for isolated murine laminin of sera from the two monkeys were comparable. However, when yolk sac homogenates were tested on ELISA, antibodies from LAM4 had greater binding than LAM3, which was further supported by immunoelectron microscopy. These differences in antibody binding were explained by the findings that antibodies from LAM4 recognized more epitopes than LAM3 and that LAM4 recognized specific epitopes not recognized by LAM3. These antibodies caused reductions in the number of microvilli on the cells and the cell sizes of the yolk sac endoderm. In addition, uptake of [14C]methionine, [14C]sucrose and [14C]valine by yolk sacs from embryos cultured on serum from LAM4 was less than that for LAM3. We suggest that the neural tube defects caused by the antilaminin antibodies were a result of reduced nutrient flow caused by the reduction in the number of microvilli on the cells of the yolk sac endoderm.

Animals↗
PubMed1998

[Neural tube defects (NTD)--assessment from the perspective of 25 years of studies].

The present paper illustrates the authors 25-year experience in step by step approach to the definition of environmental and genetic background of neural tube defects. Based on the birth defects registry, a complete ascertainment of all deliveries was performed in Southern Poland during two period: 1970-1972, and 1979-1981. The birth prevalence of neural tube defects (NTD), as well as other CNS malformations was determined. The empiric recurrence risk was calculated as 3.2% +/- 1.6. Based on this figure, the relative risk (RR = 37.6 p < 0.001) and heritability (h2 = 74.7 +/- 6.7) were estimated. Our own modification of Morton's complex segregation analysis was applied. Three Mendelian (dominant, additive and recessive) and one multifactorial model were tested. The results did not provide a clear cut discrimination between different models; however the lowest 2 value was obtained for additive inheritance with 61% of penetrance and the frequency of sporadic cases equaled 55%. A search for genetic markers did not support the hypothesis that HLA-A,B,C loci are equivalents of T/t like locus in mice. The results of the study on transcobalamine levels in amniotic fluid may suggests that different transcobalamine metabolism reflects phenotypic expression of genetic susceptibility to NTD development. Current research and future perspectives on genetic and environmental background of NTD are also presented.

Amniotic Fluid↗
PubMed1999

Folic acid and neural tube defects. Good news at last!

QUESTION: I read last year that Canada has followed the United States in fortifying flour with folic acid to prevent neural tube defects. Do we know yet whether this strategy is working? ANSWER: In Canada, flour is fortified with folic acid to a level of 0.15 mg/100 g. Although a mandatory date was set for November 1, 1998, most if not all companies implemented the change on or before January 1, 1998. Recent figures from the United States, where the deadline for fortification was January 1998, show that by March 1999, mean folate levels in flour doubled, substantially decreasing the risk for neural tube defects.

Canada↗
PubMed1977

The origin of the rapidly adhering cells found in amniotic fluids from foetuses with neural tube defects.

The number and morphologies of cells rapidly adhering to glass (RA cells) found in amniotic fluids from foetuses with neural tube defects is independent of soluble factors in the supernatant fluid. Cells taken directly from brain and spinal cord of normal foetuses, which are rapidly adherent in culture, show numerous similarities to those RA cells which are present in the amniotic fluids of foetuses with neural tube defects. This suggests that RA cells in amniotic fluid may be reliably used as a diagnostic marker of foetal lesions involving neural tissue, in particular spina bifida and anencephaly. Other RA cells extracted from foetal peritoneal cavity and bone marrow also have distinctive morphologies and may be useful in early antenatal diagnosis of congenital defects such as exomphalos.

Amniotic Fluid↗
PubMed1985

Examination of fetuses with a pre-termination diagnosis of neural tube defect or hydrocephalus.

Fifty-five fetuses with a pre-termination diagnosis of neural tube defect or hydrocephalus were examined. Termination was carried out on the basis of an elevated amniotic alpha-fetoprotein in 24 and on ultrasound examination in 31. Although pre-termination diagnosis was confirmed in 45 cases, a new or more refined diagnosis was made in 10. There was a high incidence of non-neural tube malformations. Fetuses terminated in a prenatal diagnosis screening programme should always be examined to establish the exact diagnosis for the provision of recurrence risks for genetic counselling and as a quality control for the test involved.

Abnormalities, Multiple↗
PubMedDate not supplied

Association of neural tube defects and folic acid food fortification in Canada.

Many women do not receive folic acid supplements before conception. In response, most of Canada's cereal grain products were being fortified with folic acid by January, 1998, thereby providing an additional 0.1-0.2 mg per day of dietary folate to the Canadian population. We assessed the effect of supplementation on prevalence of open neural tube defects in the province of Ontario. Among 336 963 women who underwent maternal serum screening over 77 months, the prevalence of open neural tube defects declined from 1.13 per 1000 pregnancies before fortification to 0.58 per 1000 pregnancies thereafter (prevalence ratio 0.52, 95% CI 0.40-0.67, p<0.0001). At a population level, folic acid food fortification is associated with a pronounced reduction in open neural tube defects.

Adult↗
PubMed1993

Absorption of pteroylpolyglutamates in mothers of infants with neural tube defects.

The ability to hydrolyse and absorb pteroylpolyglutamates (PteGlun) included in a standard meal in mothers who had given birth to an infant with a neural tube defect was tested by comparing them with mothers who had not had any infants with this defect. When compared with control mothers working in the research unit in which the study was performed, case mothers had significantly lower baseline serum and erythrocyte folate levels, and smaller increases in serum folate following the meal containing PteGlun. However, all estimates of folate were similar when case mothers were compared with a group of mothers who were friends of the case mothers. The results show that the higher the baseline levels of serum and erythrocyte folate the greater the increase in serum folate after the test meal. Fitting a model for the serum folate response curve resulted in coefficients which differed significantly between case mothers and all control mothers. We conclude that intestinal hydrolysis of PteGlun taken orally is not impaired in mothers who have had infants with neural tube defects when compared with control mothers with similar baseline folate levels, although the curves describing the response to the meal for the two groups do differ significantly. Further investigation is required to determine the mechanism underlying this difference.

Adult↗