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PubMed2004

Methylmalonic acid in amniotic fluid and maternal urine as a marker for neural tube defects.

To evaluate the implication of methymalonic acid (MMA) in the early diagnosis of neural tube defects (NTD), a quantitative assay for MMA was established by using gas chromatography-mass spectrometry with stable isotope of MMA as an internal standard. Amniotic fluid and maternal urine MMA concentration, maternal serum folate, red blood cell folate and vitamin B12 levels were measured in the middle term of NTD-affected and normal pregnancies. Amniotic fluid and maternal urine MMA concentrations in the middle term of NTD affected pregnancies (1.4 +/- 0.9 micromol/L, and 22.1 +/- 12.6 nmol/micromol creatinine) were significantly higher than that of normal pregnancies (1.0 +/- 0. 4 micromol/L, and 2.5 +/- 1.1 nmol/micromol creatinine). There was no significant difference between normal and NTD pregnancies for serum folate, red blood cell folate and vitamin B12 levels. The results suggested that MMAs in amniotic fluid and maternal urine are sensitive markers for early diagnosis of NTD. Vitamin B12 is an active cofactor involved in the remethylation of homocycteine and its deficiency is an independent risk factor for NTD. MMA is a specific and sensitive marker for intracellular vitamin B12 deficiency. This study suggests that it is necessary to monitor the vitamin B12 deficiency and advocates vitamin B12 supplementation with folate prevention program.

Adult↗
PubMed1978

Early prenatal diagnosis of neural-tube defects by ultrasound-guided fetoscopy.

In three fetuses with neural-tube defects (N.T.D.s) the lesions were clearly seen by fetoscopy in the second trimester. In a fourth fetus, in which the diagnosis of N.T.D. was suspected because of raised amniotic-fluid alpha-fetoprotein, spina bifida was excluded by fetoscopic examination and a normal baby was delivered at term. Ultrasound-guided fetoscopy has a place in the diagnosis of N.T.D.s when the results of other investigations are conflicting or inconclusive, and may be useful in assessing the severity of a lesion.

Amniocentesis↗
PubMed2004

Folic acid supplements to prevent neural tube defects: trends in East of Ireland 1996-2002.

Promotion of folic acid to prevent neural Tube Defects (NTD) has been ongoing for ten years in Ireland, without a concomitant reduction in the total birth prevalence of NTD. The effectiveness of folic acid promotion as the sole means of primary prevention of NTD is therefore questionable. We examined trends in folic acid knowledge and peri-conceptional use from 1996-2002 with the aim of assessing the value of this approach. From 1996-2002, 300 women attending ante-natal clinics in Dublin hospitals annually were surveyed regarding their knowledge and use of folic acid. During the period the proportion who had heard of folic acid rose from 54% to 94% between 1996 and 2002 (c2 test for trend: p<0.001). Knowledge that folic acid can prevent NTD also rose from 21% to 66% (c2 test for trend: p<0.001). Although the proportion who took folic acid during pregnancy increased from 14% to 83% from 1996 to 2002 (c2 test for trend: p<0.001), peri-conceptional intake did not rise above 24% in any year. There is a high awareness of folic acid and its relation to NTD, which is not matched by peri-conceptional uptake. The main barrier to peri-conceptional uptake is the lack of pregnancy planning. To date promotional campaigns appear to have been ineffective in reducing the prevalence of NTD in Ireland. Consequently, fortification of staple foodstuffs is the only practical and reliable means of primary prevention of NTD.

Adult↗
PubMed1999

East Ireland 1980-1994: epidemiology of neural tube defects.

STUDY OBJECTIVE: The objective of the study was to describe the epidemiology of neural tube defects (NTD) in the eastern region of Ireland using the EUROCAT register of congenital malformations. DESIGN, SETTING AND PATIENTS: EUROCAT registries monitor the prevalence of congenital anomalies in defined populations using multiple sources for case ascertainment. All cases of NTD on the Dublin EUROCAT register born between 1980 and 1994 were extracted and analysed. The crude birth prevalence rate for all NTD, spina bifida, anencephaly and encephalocoele were calculated for each year. Parameters measured were: sex ratio, stillbirth rate, proportion of low birth-weight babies (< 2500 g) and the proportion who were premature (< 37 weeks gestation). MAIN RESULTS: Of 821 NTD cases, 419 (51.0%) had spina bifida, 322 (39.2%) had anencephaly, 69 (8.4%) had encephalocoele and 11 (1.3%) were iniencephalic. The crude birth prevalence of NTD decreased fourfold from 46.9/10,000 births in 1980 to 11.6/10,000 in 1994. The downward trend ceased during the early 1990's. Younger mothers had significantly higher rates of NTD affected births. Twenty two per cent of NTD cases had additional non-central nervous system anomalies. In 40 cases, there was a previous family history of NTD in siblings. Seasonal effects in birth prevalence were observed. Birth notification was the most frequent mechanism of ascertainment. CONCLUSION: There was a marked fall in the birth prevalence of NTD during the 15 year period. This change was real and not accounted for by pre-natal screening and diagnostic practises with termination of pregnancy, which is not legally permissible in Ireland. Dietary factors may have had an influence. Rates of NTD in this region are still higher than many other parts of Europe. Primary prevention strategies through increased folic acid intake are necessary to further reduce NTD affected births.

Anencephaly↗
PubMed1999

Genetic polymorphisms in methylenetetrahydrofolate reductase and methionine synthase, folate levels in red blood cells, and risk of neural tube defects.

Folic acid administration to women in the periconceptional period reduces the occurrence of neural tube defects (NTDs) in their offspring. A polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR), 677C-->T, is the first genetic risk factor for NTDs in man identified at the molecular level. The gene encoding another folate-dependent enzyme, methionine synthase (MTR), has recently been cloned and a common variant, 2756A-->G, has been identified. We assessed genotypes and folate status in 56 patients with spina bifida, 62 mothers of patients, 97 children without NTDs (controls), and 90 mothers of controls, to determine the impact of these factors on NTD risk. Twenty percent of cases and 18% of case mothers were homozygous for the MTHFR polymorphism, compared to 11% of controls and 11% of control mothers, indicating that the mutant genotype conferred an increased risk for NTDs. The risk was further increased if both mother and child had this genotype. The MTR polymorphism was associated with a decreased O.R. (O.R.); none of the cases and only 10% of controls were homozygous for this variant. Red blood cell (RBC) folate was lower in cases and in case mothers, compared to their respective controls. Having a RBC folate in the lowest quartile of the control distribution was associated with an O.R. of 2.56 (95% CI 1.28-5.13) for being a case and of 3.05 (95% CI 1.54-6.03) for being a case mother. The combination of homozygous mutant MTHFR genotype and RBC folate in the lowest quartile conferred an O.R. for being a NTD case of 13.43 (CI 2.49-72.33) and an O.R. for having a child with NTD of 3.28 (CI 0.84-12.85). We propose that the genetic-nutrient interaction--MTHFR polymorphism and low folate status--is associated with a greater risk for NTDs than either variable alone.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1998

[Incidence of neural tube defects in the Magdeburg administrative district].

The Magdeburg Register of birth defects includes information on the incidence rate of neural tube defects (NTD) in the city of Magdeburg since 1980, and in the Regierungsbezirk (administrational district) since 1987. The average prevalence of NTD was 16.4 per 10,000 births in the city of Magdeburg, and 12 per 10,000 births in the surrounding counties. Besides of this significant difference between the city and counties, there are conspicuous variations from one year to the next. In 1987 the prevalence of NTD was about 27 per 10,000 births in the city of Magdeburg whereas the observed prevalence in the countryside was about 19 per 10,000 births. Different eating habits and/or increased teratogenic influences in the city may be considered as causes. In 1997 there was also a high rate of incidence of NTD in the city of Magdeburg--16.4 per 10,000 births. The incidence rate of NTD in the counties (about 10 per 10,000) births) is again lower than in the city. Because of these incidence rates, we may assume that the examined population is insufficiently protected by folic acid in the preconceptional stage.

Causality↗
PubMed1979

Prenatal diagnosis of chromosomal abnormalities and neural tube defects.

We have reviewed the current status of prenatal diagnosis for chromosomal indications and for neural tube defects. The number of pregnancies monitored will increase as greater resources become available and as public education about genetics increases. The methodology has proved to be a powerful means of preventing the birth of individuals with significant genetic defects, thereby sparing both parents and society from the burdens produced by such disorders. In the future, it is likely to be even more effective.

Amniocentesis↗
PubMed1984

Neural tube defects in Eastern Ontario and Western Quebec: demography and family data.

This paper reports the results of a study of families in the Eastern Ontario/Western Quebec region who had a child born with a neural tube defect during the years 1969-1981. As in several other geographic areas, the prevalence of neural tube defects at birth has fallen from previous levels. However, there was no evidence of further decline during the period of study. Socioeconomic and ethnic influences were noted, but there was no evidence of seasonal variation or any correlation with maternal age or parity. There was support for a causative role of maternal fever in some cases. The rates of miscarriage varied between pregnancies before and those after the proband, and there was an excess of males born prior to the proband. Family studies showed a 2.4% risk for sibs born after the proband and an excess of affected relatives on the maternal side. Knowledge of rates of occurrence in relatives is useful for counseling and the interpretation of the results of alpha-fetoprotein screening.

Abortion, Spontaneous↗
PubMed1994

Periodic health examination, 1994 update: 3. Primary and secondary prevention of neural tube defects. Canadian Task Force on the Periodic Health Examination.

OBJECTIVE: To make recommendations on nutritional interventions and screening manoeuvres to prevent the birth of infants with neural tube defects (NTDs). OPTIONS: Folic acid consumption through diet or supplementation in women at low risk and at high risk of having a fetus with an NTD, and maternal serum alpha-fetoprotein (MSAFP) screening in low-risk pregnancies. OUTCOMES: A reduction in the incidence rate of NTDs and potentially harmful effects of false-positive results of screening tests (i.e., abortion of a normal fetus). EVIDENCE: A MEDLINE search with the use of medical subject headings "neural tube defects," "prenatal diagnosis" and "prevention and control" identified 103 original articles published between January 1979 and March 1993. Two reviewers extracted the data by applying the rules of evidence developed by the Canadian Task Force on the Periodic Health Examination. VALUES: The task force's evidence-based methods and values were used; high value was placed on prevention of NTDs and on limitation of the harmful effects of a pregnancy involving a fetus with an NTD. BENEFITS, HARMS AND COSTS: Evidence suggests that folic acid supplementation can decrease the incidence rate of NTDs in low-risk pregnancies by 40% to 60% with no adverse effects. MSAFP screening between the 16th and 18th weeks of gestation can reach a sensitivity of 83% and a specificity of 98% when it is used as part of an organized program. The effect of screening on the incidence rate of NTDs depends on whether affected fetuses are aborted. RECOMMENDATIONS: All women of childbearing age should be advised to increase their consumption of folic acid through diet or supplementation to 0.4 mg/d beginning 1 month before pregnancy and ending at the start of the second trimester. MSAFP screening is recommended in low-risk pregnancies only when it is part of a screening program that includes access to all necessary diagnostic services. High-risk women should be referred to genetic counselling before they plan a pregnancy. VALIDATION: These recommendations are comparable to the current recommendations of the US Centers for Disease Control and Prevention, the Society of Obstetricians and Gynaecologists of Canada, the Canadian Laboratory Centre for Disease Control and the Canadian College of Medical Geneticists, and they were validated through external review. SPONSOR: These guidelines were developed and endorsed by the Canadian task force, which funded by Health Canada.

Canada↗
PubMed1994

Folic acid and neural tube defects: the current evidence and implications for prevention.

The results of the MRC Vitamin Study have established the specific role of folic acid in the prevention of neural tube defects. Folic acid supplementation (4 mg/day) at the time of conception reduced the recurrence rate by about 70%. Evidence from observational studies and the Hungarian randomized trial (that used 0.4-0.8 mg/day supplemental folic acid) indicates that a similar level of prevention can be achieved among women who have not already had an affected pregnancy and that this may be achieved with a lower dose of folic acid. The medical implications of these results are important. (1) Women planning a pregnancy should take folic acid supplements. (2) Because a large proportion of pregnancies are unplanned and many of those that are planned will occur in women who will not have taken folic acid supplements, a complementary general public health strategy is needed, based on dietary advice and food fortification designed to achieve the benefit with adequate safety. (3) Any public health prevention strategy needs to be monitored for efficacy and possible harm. (4) Research is needed on the dose-response relationship between folic acid and neural tube defect prevention and the mechanism of action.

Dose-Response Relationship, Drug↗
PubMed2000

Decline in prevalence of neural tube defects in a high-risk region of the United States.

OBJECTIVES: To conduct surveillance for neural tube defects (NTDs) in a high-risk region of the United States and to prevent occurrence and recurrence of NTDs through the periconceptional use of folic acid supplements. DESIGN: Active and passive methods were used for surveillance of NTD-affected pregnancies and births during a 6-year period (October 1992-September 1998). Individual genetic counseling was used to prevent NTD recurrences and a public awareness campaign was used to reduce NTD occurrences. SETTING: State of South Carolina. PATIENTS: All cases of spina bifida, anencephaly, and encephalocele identified among 278 122 live births and fetal deaths to South Carolina residents during 1992-1998 were included. MAIN OUTCOME MEASURE: Changes in occurrence and recurrence rates during a 6-year period. RESULTS: Over the 6 years of surveillance, the prevalence rates for NTDs decreased from 1.89 to.95 cases per 1000 live births and fetal deaths. The prevalence decrease is explained primarily by a decrease in cases of spina bifida. Isolated NTDs accounted for 297/360 (82%) NTDs and 63/360 (18%) had at least 1 other structural anomaly. Females predominated among isolated NTDs but the sex distribution was equal among NTD cases with other anomalies. Prevalence rates for whites (1.48 cases per 1000 live births and fetal deaths) were higher than rates for blacks (.87 cases per 1000 live births and fetal deaths). There were no NTD recurrences in 113 subsequent pregnancies to mothers of infants with isolated NTDs who took periconceptional folic acid. The rate of periconceptional folic acid use among women of childbearing years increased from 8% to 35% during the 6-year project period. CONCLUSION: The prevalence of NTDs in a high-risk region has declined coincident with the increased periconceptional use of folic acid supplements among women of childbearing age.neural tube defects, high-risk region, birth defects, folic acid, spina bifida, anencephaly, encephalocele.

Adolescent↗
PubMed1992

Neural tube defects in the middle belt of Nigeria.

Forty-two babies were found to have neural tube defects during a 3-year prospective study in a large cosmopolitan West African city. An incidence of 7/1000 deliveries was noted. The commonest defect was meningomyelocele, in 45 per cent of cases. Other defects comprised anencephaly (5 per cent), Arnold-Chiari malformation (7 per cent), encephalocele (19 per cent), occipital meningocele (14 per cent) and spina bifida occulta (10 per cent). No case of consanguinity was encountered. More defects were found among females and low birth weight infants among those whose mothers were aged between 20 and 30 years, and in mothers with parity of four and above. The commonest associated defect was talipes equinus in 15/42 (36 per cent) infants. Developmental assessments (neurological follow-up status) done at the age of 18 months on five surviving cases of meningomyelocele showed very poor development.

Female↗
PubMed1983

[Prenatal recognition of genetic diseases and neural tube defects].

A growing number of metabolic genetic defects can be diagnosed prenatally; however, the most common genetic diseases defy our efforts so far. Promising new avenues are mentioned. Efforts to diagnose neural tube defects in early pregnancy have gained wide acceptance. The most widely used method is alpha-fetoprotein (AFP)-determination in amnion fluid supplemented by ultrasound examination and particularly successfully by the ACHE-(acetyl-cholinesterase)gel test. In many countries, a general introduction of AFP-screening in maternal serum for neural tube defects is being considered. Two large field studies, each including some 24,000 patients, will soon be completed in Giessen and Hannover. They were designed to supplement the data from Great Britain in judging the advisability of mass screening of maternal serum AFP in the second trimenon in a low-incidence area such as Western Germany. The concluding discussion touches on future aspects of prenatal diagnosis and ethical considerations.

Acetylcholinesterase↗
PubMed2000

Chronological changes of re-closure capacity in surgically induced spinal open neural tube defects of chick embryos.

To investigate the re-closure capacity of surgically induced spinal open neural tube defects (ONTD) and its correlation to the cell proliferation activity in embryonic stages, longitudinal incisions of 3- or 6-somite lengths were made in neural tubes of chick embryos at Hamburger and Hamilton stage 18-19, and the length of the ONTDs was measured on postoperative days 2, 3, 5, 7, and 10. The results demonstrated that re-closure occurred more actively when the incision length was shorter. The chronological changes in the re-closure capacity of the ONTDs paralleled the proliferative activity of the neural tube. We conclude that surgically induced spinal ONTDs may be remodeled in early chick embryos and that manipulation of cell dynamics can enhance the re-closure process in the embryonic spinal cord tissue.

Animals↗
PubMed1975

Observations on patients with neural-tube defects in a metropolitan hospital clinic: an epidemiological history.

A survey of the population of the Spina Bifida Service (107 patients) of Georgetown University Hospital, Washington, D.C., and of a control population in the same hospital revealed that, although situated in an ethnically heterogeneous area, Service patients with a history of neural-tube defects in siblings or family significantly more often had ancestors on both sides from the British Isles than did either isolated cases or the controls. In addition, of 107 families reviewed, nine had more than one affected child, nine had a positive family history for neural-tube defects, and nine of the patients and seven of an estimated total of 220 siblings had an unrelated major birth-defect. These incidences are among the highest published so far. Contrary to other surveys, there was no deficiency of twinning among the sibships, nor of males among the Spina Bifida Service patients. These observations indicate the desirability of studying each population of patients with neural-tube defects in order to provide more realistic counseling and so that clues may be gathered as to the genetic mechanisms and environmental factors which led to the production of such defects.

Consanguinity↗
PubMed1999

Neural tube defect prevalence in California (1990-1994): eliciting patterns by type of defect and maternal race/ethnicity.

This study presents race/ethnicity-specific prevalence estimates of neural tube defects (NTDs) in California using 5 years of population-based data. NTD prevalence estimates include prenatally diagnosed cases, as well as cases diagnosed at birth. The California NTD Registry contains NTD case reports identified through the California Maternal Serum Alpha-Feto Protein (AFP) Screening Program, the California Birth Defects Monitoring Program, and additional reports from clinicians and clinics throughout the state. These data were used to estimate NTD prevalence in a large population-based study (n = 1,618,279). The overall NTD prevalence among White, Black, Hispanic, and Asian women are reported, as well as race/ethnic prevalence, for anencephaly, spina bifida, and encephalocele. Rates are expressed as the number of cases per 1,000 women screened between 1990 and 1994. Among 1,457 women with an NTD-affected pregnancy, the overall rate for anencephaly, spina bifida, and encephalocele was 0.49 (95% CI 0.46-0.53), 0.42 (95% CI 0.38-0.45), and 0.08 (95% CI 0.07-0.09), respectively. When these types of NTDs are combined, Hispanic women had the highest overall rate (1.12, 95% CI 1.04-1.21), followed by Whites (0.96, 95% CI 0.89-1.04), Blacks (0.75, 95% CI 0.59-0.91), and Asians (0.75, 95% CI 0.60-0.90). Hispanic women were 45% more likely than White women to have a pregnancy affected with anencephaly (odds ratio = 1.45, 95% CI 1.24-1.70), while Asian women were over two times less likely to have a pregnancy affected with spina bifida (odds ratio = 0.44, 95% CI 0.29-0.65). Considerable variation exists in the prevalence of NTDs by race/ethnicity and by type of NTD, with Hispanic women exhibiting the highest overall NTD rate.

Anencephaly↗
PubMed1989

Towards the prevention of neural tube defects.

The value of maternal periconceptional vitamin supplementation in preventing the conception of fetuses with neural tube defects has yet to be assessed in a properly designed study. Avoidance of the birth of affected infants continues to rest on second-trimester maternal serum alphafetoprotein screening. The performance of screening programmes in achieving this objective is reviewed.

Female↗
PubMed2007

Folic acid prevents neural tube defects: international comparison of awareness among obstetricians/gynecologists and urologists.

AIM: It has been suggested that periconceptional intake of folic acid prevents risks of having fetuses afflicted with neural tube defects. We aim to internationally investigate knowledge of the role of folic acid and attitudes toward the life-style of young women of child-bearing age among obstetricians/gynecologists and urologists. METHODS: A questionnaire was sent to obstetricians/gynecologists and urologists residing in Japan, South Korea, Taiwan, North America, Europe, Australia and New Zealand by post or e-mail. The investigation was conducted between December 2002 and November 2004. RESULTS: A mean of 91% of obstetricians/gynecologists and 56% of urologists are aware of the role of folic acid, where Asian urologists knew less compared to those of North America, Europe, Australia and New Zealand. A majority of doctors always, or occasionally, recommend folic acid supplements or multivitamins, well-balanced meals, and the cessation of smoking and drinking. An average of 85% of doctors believes information on folic acid should be disseminated to young women. CONCLUSIONS: A majority of obstetricians/gynecologists and urologists know the importance of periconceptional folic acid in reducing the risk of neural tube defects and have been advising young women to improve their lifestyle.

Awareness↗