Maternal myo-inositol, glucose, and zinc status is associated with the risk of offspring with spina bifida

Neural tube defects in mice with reduced levels of inositol 1,3,4-trisphosphate 5/6-kinase

Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) is a key regulatory enzyme at the branch point for the synthesis of inositol hexakisphosphate (IP(6)), an intracellular signaling molecule implicated in the regulation of ion channels, endocytosis, exocytosis, transcription, DNA repair, and RNA export from the nucleus. IP(6) also has been shown to be an integral structural component of several proteins. We have generated a mouse strain harboring a beta-galactosidase (betagal) gene trap cassette in the second intron of the Itpk1 gene. Animals homozygous for this gene trap are viable, fertile, and produce less ITPK1 protein than wild-type and heterozygous animals. Thus, the gene trap represents a hypomorphic rather than a null allele. Using a combination of immunohistochemistry, in situ hybridization, and betagal staining of mice heterozygous for the hypomorphic allele, we found high expression of Itpk1 in the developing central and peripheral nervous systems and in the paraxial mesoderm. Examination of embryos resulting from homozygous matings uncovered neural tube defects (NTDs) in some animals and axial skeletal defects or growth retardation in others. On a C57BL/6 x 129(P2)Ola background, 12% of mid-gestation embryos had spina bifida and/or exencephaly, whereas wild-type animals of the same genetic background had no NTDs. We conclude that ITPK1 is required for proper development of the neural tube and axial mesoderm.

Nutrient pathways and neural tube defects: a semi-Bayesian hierarchical analysis

BACKGROUND

We used conventional and hierarchical logistic regression to examine the association of neural tube defects (NTDs) with intake of 26 nutrients that contribute to the mechanistic pathways of methylation, glycemic control, and oxidative stress, all of which have been implicated in NTD etiology. The hierarchical approach produces more plausible, more stable estimates than the conventional approach, while adjusting for potential confounding by other nutrients.

METHODS

Analyses included 386 cases and 408 nonmalformed controls with complete data on nutrients and potential confounders (race/ethnicity, education, obesity, and intake of vitamin supplements) from a population-based case-control study of deliveries in California from 1989 to 1991. Nutrients were specified as continuous, and their units were standardized to have a mean of zero and standard deviation (SD) of 1 for comparability of units across pathways. ORs reflect a 1-SD increase in the corresponding nutrient.

RESULTS

Among women who took vitamin supplements, semi-Bayesian hierarchical modeling results suggested no associations between nutrient intake and NTDs. Among women who did not take supplements, both conventional and hierarchical models (HM) suggested an inverse association between lutein intake and NTD risk (HM odds ratio [OR] = 0.6; 95% confidence interval = 0.5-0.9) and a positive association with sucrose (HM OR 1.4; 1.1-1.8) and glycemic index (HM OR 1.3; 1.0-1.6).

CONCLUSIONS

Our findings for lutein, glycemic index, and sucrose suggest that further study of NTDs and the glycemic control and oxidative stress pathways is warranted.

Modeling neural tube defects in the mouse

Neural tube defects (NTDs) are among the most common structural birth defects observed in humans. Mouse models provide an excellent experimental system to study the underlying causes of NTDs. These models not only allow for identification of the genes required for neurulation, they provide tractable systems for uncovering the developmental, pathological and molecular mechanisms underlying NTDs. In addition, mouse models are essential for elucidating the mechanisms of gene-environment and gene-gene interactions that contribute to the multifactorial inheritance of NTDs. In some cases these studies have led to development of approaches to prevent NTDs and provide an understanding of the underlying molecular mechanism of these therapies prevent NTDs.

Syndromes, disorders and maternal risk factors associated with neural tube defects (VI)

Neural tube defects (NTDs) may be associated with syndromes, disorders, and maternal and fetal risk factors. This article provides a comprehensive review of the syndromes, disorders, and maternal and fetal risk factors associated with NTDs, including maternal fumonisin consumption, periconceptional zinc deficiency, parental occupational exposure and residential proximity to pesticides, lower socioeconomic status, fetal alcohol syndrome, mutations in the VANGL1 gene, human athymic Nude/SCID fetus, and single nucleotide polymorphism in the NOS3 gene. NTDs associated with these syndromes, disorders, and maternal and fetal risk factors are a rare but important cause of NTDs. The recurrence risk and the preventive effect of maternal folic acid intake in NTDs associated with syndromes, disorders and maternal risk factors may be different from those of nonsyndromic multifactorial NTDs. Perinatal diagnosis of NTDs should alert doctors to the syndromes, disorders, and maternal and fetal risk factors associated with NTDs, and prompt thorough etiologic investigation and genetic counseling.

Plasma concentrations of carbohydrates and sugar alcohols in term newborns after milk feeding

Nonglucose carbohydrates such as galactose, mannose, and inositol play a clinically important role in fetal and neonatal nutrition, though little is known about their metabolism in the neonate. The aim of this study was to determine whether postprandial changes in plasma carbohydrate and sugar alcohol concentrations are affected by clinical variables such as postnatal age (PNA), milk type, feeding volume, or feeding duration in term newborns. Neonates (n = 26) taking intermittent enteral feedings were enrolled. Blood samples were obtained at baseline (immediately before the start of a feeding) and at 2-3 subsequent time points up to 110 min. Postprandial rise was only observed for plasma glucose concentrations [Glu] and plasma galactose concentrations [Gal] and clinical variables did not predict this change. Despite equimolar delivery in milk, the median of [Glu] rise minus [Gal] rise from baseline to second postprandial plasma sample was 674 microM (-38, 3333 microM; p < 0.0001), reflecting efficient hepatic first-pass metabolism of galactose. A significant PNA effect on [Gal] was observed such that for each day PNA there was an 18% decrease in [Gal] (p = 0.03). [Gal] are a function of PNA, suggesting maintenance of a significant ductus venosus shunt in term infants.

Haplotype-specific expression of the human PDGFRA gene correlates with the risk of glioblastomas

Aberrant expression of the platelet-derived growth factor alpha-receptor (PDGFRA) gene has been associated with various diseases, including neural tube defects and gliomas. We have previously identified 5 distinct haplotypes for the PDGFRA promoter region, designated H1, H2alpha, H2beta, H2gamma and H2delta. Of these haplotypes H1 and H2alpha are the most common, whereby H1 drives low and H2alpha high transcriptional activity in transient transfection assays. Here we have investigated the role of these PDGFRA promoter haplotypes in gliomagenesis at both the genetic and cellular level. In a case-control study on 71 glioblastoma patients, we observed a clear underrepresentation of H1 alleles, with pH1 = 0.141 in patients and pH1 = 0.211 in a combined Western European control group (n = 998, p < 0.05). Furthermore, in 3 out of 4 available H1/H2alpha heterozygous human glioblastoma cell lines, H1-derived mRNA levels were more than 10-fold lower than from H2alpha, resulting at least in part from haplotype-specific epigenetic differences such as DNA methylation and histone acetylation. Together, these results indicate that PDGFRA promoter haplotypes may predispose to gliomas. We propose a model in which PDGFRA is upregulated in a haplotype-specific manner during neural stem cell differentiation, which affects the pool size of cells that can later undergo gliomagenesis.

Genes in glucose metabolism and association with spina bifida

The authors test single nucleotide polymorphisms (SNPs) in coding sequences of 12 candidate genes involved in glucose metabolism and obesity for associations with spina bifida. Genotyping was performed on 507 children with spina bifida and their parents plus anonymous control DNAs from Hispanic and Caucasian individuals. The transmission disequilibrium test was performed to test for genetic associations between transmission of alleles and spina bifida in the offspring (P < .05). A statistically significant association between Lys481 of HK1 (G allele), Arg109Lys of LEPR (G allele), and Pro196 of GLUT1 (A allele) was found ( P = .019, .039, and .040, respectively). Three SNPs on 3 genes involved with glucose metabolism and obesity may be associated with increased susceptibility to spina bifida.

Maternal hyperhomocysteinaemia is a risk factor for congenital heart disease

OBJECTIVE

To investigate the inter-relation between mother and infant homocysteine, folate and vitamin B12 status and the risk of a child with congenital heart disease (CHD).

DESIGN

Case-control study.

SETTING

Erasmus MC, University Medical Centre, Rotterdam, the Netherlands.

POPULATION

Participants were 149 case-mothers and their children with CHD (n = 151) and 183 control-mothers with their children (n = 175).

METHODS

Approximately 17 months after the index-pregnancy maternal fasting, children's random venous blood samples were drawn to measure plasma total homocysteine, serum and red blood cell (RBC) folate, and serum vitamin B12 concentrations. Data were compared between cases and controls using the Mann-Whitney U test. The biochemical parameters were dichotomised according to the cutoff value of the 10th percentile of vitamin concentrations and the 90th percentile of homocysteine concentrations based on control data. Risk estimates for the association between CHD and the biochemical parameters were estimated in a logistic regression model.

MAIN OUTCOME MEASURES

Medians (minimum-maximum) and odds ratios (OR) (95% confidence intervals [CI]).

RESULTS

The OR (95% CI) of having a child with CHD was 2.9 (1.4-6.0) for maternal hyperhomocysteinaemia (>14.3 micromol/l). This finding is substantiated by a significant concentration-dependent risk (Ptrend = 0.004). Hyperhomocysteinaemic case-mothers showed significantly lower serum folate and vitamin B12 concentrations than normohomocysteinaemic case-mothers. Serum and RBC folate concentrations were significantly higher in case-children than that in control-children.

CONCLUSIONS

Maternal hyperhomocysteinaemia is associated with an increased risk of CHD, partially due to low folate and vitamin B12 status. The folate status of children warrants further investigation.

Current perspectives on the genetic causes of neural tube defects

Neural tube defects (NTDs) are a group of severe congenital abnormalities resulting from the failure of neurulation. The pattern of inheritance of these complex defects is multifactorial, making it difficult to identify the underlying causes. Scientific research has rapidly progressed in experimental embryology and molecular genetics to elucidate the basis of neurulation. Crucial mechanisms of neurulation include the planar cell polarity pathway, which is essential for the initiation of neural tube closure, and the sonic hedgehog signaling pathway, which regulates neural plate bending. Genes influencing neurulation have been investigated for their contribution to human neural tube defects, but only genes with well-established role in convergent extension provide an exciting new set of candidate genes. Biochemical factors such as folic acid appear to be the greatest modifiers of NTDs risk in the human population. Consequently, much research has focused on genes of folate-related metabolic pathways. Variants of several such genes have been found to be significantly associated with the risk of neural tube defects in more studies. In this manuscript, we reviewed the current perspectives on the causes of neural tube defects and highlighted that we are still a long way from understanding the etiology of these complex defects.

Etiology, pathogenesis and prevention of neural tube defects

Spina bifida, anencephaly, and encephalocele are commonly grouped together and termed neural tube defects (NTD). Failure of closure of the neural tube during development results in anencephaly or spina bifida aperta but encephaloceles are possibly post-closure defects. NTD are associated with a number of other central nervous system (CNS) and non-neural malformations. Racial, geographic and seasonal variations seem to affect their incidence. Etiology of NTD is unknown. Most of the non-syndromic NTD are of multifactorial origin. Recent in vitro and in vivo studies have highlighted the molecular mechanisms of neurulation in vertebrates but the morphologic development of human neural tube is poorly understood. A multisite closure theory, extrapolated directly from mouse experiments highlighted the clinical relevance of closure mechanisms to human NTD. Animal models, such as circle tail, curly tail, loop tail, shrm and numerous knockouts provide some insight into the mechanisms of NTD. Also available in the literature are a plethora of chemically induced preclosure and a few post-closure models of NTD, which highlight the fact that CNS malformations are of hetergeneitic nature. No Mendelian pattern of inheritance has been reported. Association with single gene defects, enhanced recurrence risk among siblings, and a higher frequency in twins than in singletons indicate the presence of a strong genetic contribution to the etiology of NTD. Non-availability of families with a significant number of NTD cases makes research into genetic causation of NTD difficult. Case reports and epidemiologic studies have implicated a number of chemicals, widely differing therapeutic drugs, environmental contaminants, pollutants, infectious agents, and solvents. Maternal hyperthermia, use of valproate by epileptic women during pregnancy, deficiency and excess of certain nutrients and chronic maternal diseases (e.g. diabetes mellitus) are reported to cause a manifold increase in the incidence of NTD. A host of suspected teratogens are also available in the literature. The UK and Hungarian studies showed that periconceptional supplementation of women with folate (FA) reduces significantly both the first occurrence and recurrence of NTD in the offspring. This led to mandatory periconceptional FA supplementation in a number of countries. Encouraged by the results of clinical studies, numerous laboratory investigations focused on the genes involved in the FA, vitamin B12 and homocysteine metabolism during neural tube development. As of today no clinical or experimental study has provided unequivocal evidence for a definitive role for any of these genes in the causation of NTD suggesting that a multitude of genes, growth factors and receptors interact in controlling neural tube development by yet unknown mechanisms. Future studies must address issues of gene-gene, gene-nutrient and gene-environment interactions in the pathogenesis of NTD.

Pax1/E2a double-mutant mice develop non-lethal neural tube defects that resemble human malformations

Many mouse models exist for neural tube defects (NTDs), but only few of them are relevant for human patients that are born alive with spina bifida aperta. NTDs in humans show a complex inheritance, which most likely result from the involvement of a variety of predisposing genetic and environmental factors. Hints toward the identity of predisposing genetic factors for human NTDs could come from mouse studies on the development of the neural tube and spinal cord, as well as from studies on associated features of this type of diseases. Among such features is the observation that pregnancies affected by a neural tube defect frequently show changes in thymus morphology, and in both neonatal and maternal T-cell repertoire. The genes for E2a and Pax1 have both been implicated in not only paraxial mesodermal development, but also in that of the immune system. Moreover, Pax1 mutant mice have been shown to display NTDs in digenic mouse models. In the present study we have investigated the phenotype of E2a null mutant mice that are also heterozygous for the so-called undulated mutation in Pax1. Here we report that such double-mutant mice develop a non-lethal NTD that strongly resembles the classic human NTD: spina bifida aperta, associated with defects of the axial skeleton, immune system and urinary tract.

Free sugar and sugar alcohol concentrations in human breast milk

OBJECTIVES

The goal was to determine the free sugars and polyols in human breast milk, both term and preterm, for comparison with formula milks.

METHODS

Methodology was developed for the measurement of the free sugars and polyols in breast milk. There were 16 samples collected from women who delivered at term and 17 samples from women delivering preterm. For purposes of comparison, samples were also collected from four commercial formulas for term infants and eight from commercial formulas for preterm infants as well as one sample of cows' milk. All samples were frozen immediately and analyzed by high-performance liquid chromatography techniques.

RESULTS

Except for lactose concentrations, no significant differences were detected for all other sugars and polyols between term and preterm breast milk samples. Within breast milk samples, two patterns emerged, with one group containing additional elution peaks for compounds not yet identified. A second group did not contain these compounds. There were a number of significant differences between breast milk and formulas, particularly for inositol, glycerol, glucose, and galactose. All milks contained significant concentrations of mannose.

CONCLUSIONS

There are no significant differences among breast milk samples for free sugar and polyol concentrations except lactose. However, some milk contains additional peaks that could be of dietary or genetic origin. Formula milk has relatively high concentrations of glucose and galactose compared with breast milk, suggesting some lactose hydrolysis.

Renal-specific oxidoreductase biphasic expression under high glucose ambience during fetal versus neonatal development

BACKGROUND

Renal-specific oxidoreductase (RSOR) has been recently identified in mice kidneys of diabetic animals, and it is developmentally regulated. Its expression during fetal, neonatal, and postnatal periods was assessed under high glucose ambience.

METHODS

Whole-mount immunofluorescence and confocal microscopy were performed to assess the effect of high glucose on the morphogenesis of mice fetal kidneys. RSOR mRNA and protein expression was assessed by competitive polymerase chain reaction (PCR) and immunoprecipitation methods in embryonic kidneys (day E13 to E17) subjected to high glucose ambience and by Northern and Western blot analyses of kidneys of newborn and 1-week-old mice with hyperglycemia. The spatiotemporal changes in the RSOR expression were assessed by in situ hybridization analyses and immunofluorescence microscopy. In addition, the extent of apoptosis in the kidneys was determined by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) assay.

RESULTS

Whole-mount microscopy of the embryonic metanephroi revealed a dose-dependent disruption in the ureteric bud iterations with reduced population of the nascent nephrons. Both gene and protein expressions were reduced in day E13 to E17 metanephroi, while increased in kidneys of newborn and 1-week-old mice. In day E13 and day E15 kidneys, the RSOR was expressed in the ureteric bud branches and some of the immature tubules, and its expression was reduced with high glucose treatment. In day E17 kidneys the RSOR was expressed in the tubules of the deeper cortex, and its expression was marginally decreased. In newborn kidneys, this enzyme was expressed in the subcortical tubules and it spread to the entire width of the renal cortex in hyperglycemic state. In 1-week-old mice kidneys, the RSOR was localized to the entire cortex, and in animals with blood glucose above 300 mg/dL, its intensity increased with extension of expression into the outer medullary tubules. A dose-dependent fulminant apoptosis was observed in day E13 to E17 kidneys subjected to high glucose ambience. In newborn and 1-week-old mice control kidneys, the apoptosis was minimal although slightly increased during hyperglycemia.

CONCLUSION

High glucose has a differential effect on the RSOR expression in kidneys during the embryonic versus neonatal/postnatal period. This may partly be related to the differential degree of apoptosis, a process reflective of oxidant stress that is seen in diabetic milieu, which as previously has been shown to adversely effect the modulators of fetal development and thereby the morphogenesis of the kidney and RSOR expression.

Fetal and maternal non-glucose carbohydrates and polyols concentrations in normal human pregnancies at term

The objective of the present investigation was to determine fetal and maternal plasma concentrations of nonglucose carbohydrates and polyols in normal human pregnancies at term. Uncomplicated human pregnancies (n = 50) were studied at > or =37 wk gestation. Blood samples were obtained from umbilical artery, umbilical vein, and maternal peripheral blood at the time of elective cesarean section. Plasma concentrations of inositol, glycerol, erythritol, sorbitol, and mannose were determined by HPLC analysis. Differences between umbilical venous, umbilical arterial, and maternal concentration were tested by the two-tailed t test for paired samples. Correlations between umbilical and maternal concentration and between umbilical venoarterial concentration difference and umbilical arterial concentration were assessed by Pearson's correlation and multiple regression analysis. All newborns were appropriate for gestational age, and oxygenation and acid-base balance were within the normal range for all fetuses studied. For most of the polyols (inositol, sorbitol, and erythritol), the fetal concentration was significantly higher than the maternal concentration. The umbilical venoarterial concentration difference for inositol was -10.5 +/- 3.6 microM, for glycerol was 10 +/- 1.7 microM, for sorbitol was 3.8 +/- 0.5 microM (p < 0.001), and for mannose was 7.6 +/- 0.7 microM. There was a significant correlation between maternal concentration and umbilical venous concentration of mannose (UV(MAN) = 15.38 + 0.69 M(MAN); R(2) = 0.46; p < 0.001). These results indicate that in normal human pregnancies at term, inositol is produced by the fetus, sorbitol is produced by the placenta, and there is a significant umbilical uptake of mannose from the maternal circulation.

Myo-inositol, glucose and zinc concentrations determined in the preconceptional period, during and after pregnancy

OBJECTIVE

To determine the blood concentrations of myo-inositol, glucose and zinc before, during and after normal pregnancy.

STUDY DESIGN

Preconceptionally, at 6, 10, 20, 30 and 37 weeks amenorrhea, and 6 weeks after delivery, blood samples of 18 nulliparae and 19 multiparae were obtained and concentrations of serum inositol and glucose, and red blood cell zinc were determined. The data were analyzed using a linear mixed model.

RESULTS

The preconceptional mean (S.E.M.) inositol concentration of 21.7 (1.03) micromol/L was comparable to the concentrations at 6 and 37 weeks amenorrhea, 22.2 (1.03) micromol/L, and 19.9 (1.10) micromol/L, respectively. However, the inositol concentrations at 10 and 20 weeks amenorrhea and post partum were significantly lower than the preconceptional inositol concentration, p<0.05. The preconceptional mean (S.E.M.) glucose concentration of 3.9 (1.03) mmol/L was comparable to the concentration at 6 and 10 weeks amenorrhea, 3.9 (1.04) mmol/L and 3.8 (1.04) mmol/L respectively. Also at 20, 30 and 37 weeks amenorrhea and after delivery the glucose concentration was significantly lower than the preconceptional glucose concentration, p<0.05. Preconceptional red blood cell zinc concentrations were comparable to concentrations at 6, 10 and 20 weeks amenorrhea. At 30 and 37 weeks amenorrhea and post partum the zinc concentrations were significantly higher than in the preconceptional period (p<0.01).

CONCLUSION

The concentrations of inositol, glucose and zinc significantly change during pregnancy. However, the preconceptional blood concentrations reflect the concentrations determined in the first pregnancy trimester rather well, which is important information to be used in future studies into the role of inositol, glucose and zinc in reproductive disorders.

Periconceptional dietary intake of myo-inositol and neural tube defects in offspring

BACKGROUND

Periconceptional intake of nutrients in addition to folic acid may contribute to neural tube defect (NTD) etiologies; a likely candidate is myo-inositol. We investigated whether maternal periconceptional dietary intake of myo-inositol influenced NTD risk.

METHODS

Data were derived from a case-control study of fetuses and infants with NTDs among 1989-1991 California births. Interviews were conducted with mothers of 454 NTD cases and with mothers of 462 nonmalformed controls. A standard 100-item food frequency questionnaire was used to assess nutrient intake.

RESULTS

We observed small increases in risk, with increases slightly more evident for anencephaly, associated with intakes of myo-inositol less than the highest intake quartile, e.g., risk of anencephaly was 1.3 (0.7-2.4) among fetuses whose mothers consumed lowest versus highest intakes of myo-inositol. These small increases, however, were imprecise, and also did not indicate increasing risk with decreasing level of myo-inositol intake. Adjusted risk estimates did not differ considerably from their unadjusted counterparts.

CONCLUSIONS

Our results do not indicate that myo-inositol intake, as measured in this study, is strongly associated with risk of human NTDs.

Mouse models of neural tube defects: investigating preventive mechanisms

Neural tube defects (NTD), including anencephaly and spina bifida, are a group of severe congenital abnormalities in which the future brain and/or spinal cord fail to close. In mice, NTD may result from genetic mutations or knockouts, or from exposure to teratogenic agents, several of which are known risk factors in humans. Among the many mouse NTD models that have been identified to date, a number have been tested for possible primary prevention of NTD by exogenous agents, such as folic acid. In genetic NTD models such as Cart1, splotch, Cited2, and crooked tail, and NTD induced by teratogens including valproic acid and fumonisins, the incidence of defects is reduced by maternal folic acid supplementation. These folate-responsive models provide an opportunity to investigate the possible mechanisms underlying prevention of NTD by folic acid in humans. In another group of mouse models, that includes curly tail, axial defects, and the Ephrin-A5 knockout, NTD are not preventable by folic acid, reflecting the situation in humans in which a subset of NTD appear resistant to folic acid therapy. In this group of mutants alternative preventive agents, including inositol and methionine, have been shown to be effective. Overall, the data from mouse models suggests that a broad-based in utero therapy may offer scope for prevention of a greater proportion of NTD than is currently possible.

Epidemiology of neural tube defects

The epidemiological investigation of the common open neural tube defects (NTDs), anencephaly, and spina bifida, has a long history. The most significant finding from these past studies of NTDs was the identification of the protective effect of maternal, periconceptional supplementation with folic acid. Fortuitously, the association between folic acid and NTDs became widely accepted in the early 1990s, at a time when genetic association studies of complex traits were becoming increasingly feasible. The confluence of these events has had a major impact on the direction of epidemiological, NTD research. Association studies to evaluate genes that may influence the risk of NTDs through their role in folate-related processes, or through other metabolic or developmental pathways are now commonplace. Moreover, the study of genetic as well as non-genetic, factors that may influence NTD risk through effects on the nutrient status of the mother or embryo has emerged as a major research focus. Research efforts over the past decade indicate that gene-gene, gene-environment, and higher-order interactions, as well as maternal genetic effects influence NTD risk, highlighting the complexity of the factors that underlie these conditions. The challenge for the future is to design studies that address these complexities, and are adequately powered to detect the factors or combination of factors that influence the development of NTDs.

Maternal nutritional status and the risk for orofacial cleft offspring in humans

Periconceptional folate and folic acid intake prevents orofacial clefts (OFC) in the offspring. It has been suggested that other nutrients also play a role. We investigated the preconceptional intake of macronutrients (protein, fat, carbohydrate, fiber, and cholesterol), vitamins (vitamin A, retinol, beta-carotene, ascorbic acid, and alpha-tocopherol), minerals (calcium, phosphorus, iron, magnesium, and zinc) and food groups in mothers of OFC children and controls. At approximately 14 mo after the index pregnancy, 206 mothers of a child with a nonsyndromic OFC and 203 control mothers completed a FFQ on current food intake and a general questionnaire. After exclusion of pregnant and lactating mothers, mothers who reported a change in diet compared with the preconceptional period, and those for whom periconceptional folic acid supplement use was unclear, 182 OFC mothers and 173 control mothers were evaluated. Macronutrient, vitamin, mineral, and food group intakes were compared. After adjustment for energy, quintiles of dietary nutrient intake and odds ratios with 95% CI were calculated. The preconceptional intake of all macronutrients, vitamins, minerals, and food groups with the exception of milk (products), potatoes, pies/cookies were lower in OFC mothers than in controls. The energy-adjusted intakes of vegetable protein, fiber, beta-carotene, ascorbic acid, alpha-tocopherol, iron, and magnesium were significantly lower in cases compared with controls. Increasing intakes of vegetable protein, fiber, ascorbic acid, iron, and magnesium decreased OFC risk. In conclusion, a higher preconceptional intake of nutrients predominantly present in fruits and vegetables reduces the risk of offspring affected by OFC.

Body mass index and serum folate in childbearing age women

BACKGROUND

Higher pre-pregnancy body mass index (BMI) is associated with increased risk of neural tube defects (NTDs) and possibly other negative birth outcomes in the offspring. The mechanism for this association remains unknown. Lower maternal folate level has been implicated in the etiology of NTDs in general. The association of BMI with folate level, however, has not been investigated.

METHODS

The present study examines the association of BMI with folate level in childbearing age women before and after the 1998 U.S. folate fortification program of cereal products, using data from two cross-sectional surveys of the U.S. population, the third wave of the National Health and Nutrition Examination Survey (NHANES III; 1988-1994) and the more recent wave of this survey (NHANES 1999-2000).

RESULTS

After controlling for intake of folate in food and nutritional supplements, increased BMI in childbearing age women was associated with a lower serum folate level in both surveys (p < 0.001). Using data from NHANES 1999-2000, it was estimated that women in the 30.0 + kg/m2 BMI category would need to take an additional 350 microg/day of folate to achieve the same serum folate level as women in the < 20.0 kg/m2 category.

CONCLUSION

Lower folate level may be one mechanism linking higher maternal BMI and increased risk of NTDs in the offspring. If corroborated in future studies, findings from this study suggest a need for a higher dose of folate supplement in heavier childbearing age women.

Marginal maternal vitamin B12 status increases the risk of offspring with spina bifida

OBJECTIVE

The purpose of this study was to investigate B vitamins and homocysteine as risk factor for offspring with spina bifida.

STUDY DESIGN

Blood samples from 45 mothers and their children with spina bifida and from 83 control mothers and their children were obtained to determine the levels of serum and red blood cell folate, serum vitamin B(12), whole blood vitamin B(6), and total plasma homocysteine.

RESULTS

In the case mothers, the vitamin B(12) concentration was 21% lower (95% CI, 8%-33%) compared with control mothers. Unlike folate, vitamin B(6,) and homocysteine, a vitamin B(12) concentration of <or=185 pmol/L was associated with a 3.5-fold (95% CI, 1.3- 8.9) spina bifida risk. In children, no differences in folate, vitamin B(6), vitamin B(12), and homocysteine concentrations were observed after adjustment for the child's age.

CONCLUSION

A marginal maternal vitamin B(12) status increases the risk of an offspring with spina bifida.

Spina bifida and genetic factors related to myo-inositol, glucose, and zinc

BACKGROUND

Myo-inositol, glucose and zinc and related genetic factors are suggested to be implicated in the etiology of spina bifida. We investigated the biochemical concentrations of these nutrients and polymorphisms in the myo-inositol transporter SLC5A11, myo-inositol synthase ISYNA1, and zinc transporter SLC39A4 in association with spina bifida risk.

METHODS

Seventy-six spina bifida triads only were ascertained. In mothers, fathers, and spina bifida children polymorphisms determined were SLC5A11 (544C > T), ISYNA1 (1029A > G), and SLC39A4 (1069C > T). Serum myo-inositol and glucose, and red blood cell zinc concentrations were determined in mothers and spina bifida children. Transmission disequilibrium tests (TDT) were applied to determine associations between the polymorphisms and spina bifida. Associations between biochemical values and genotypes were studied by one-way analysis of variance (ANOVA). Interactions between alleles, biochemical values, and environmental factors were analyzed by conditional logistic regression.

RESULTS

No association between SLC5A11, ISYNA1, and SLC39A4 and spina bifida was shown, chi2SLC5A11=0.016, P=0.90; chi2SYNA1=1.52, P=0.22; chi2SLC39A4=0.016, P=0.90; and degrees of freedom (df)=1. Maternal glucose concentrations were comparable for the SLC5A11 genotypes. Significantly lower myo-inositol concentrations were observed in mothers with SLC5A11 CC-genotype, mean (SD) 14.2 (2.6)micromol/L compared to SLC5A11 TT-genotype, 17.0 (3.4)micromol/L, P <0.05 . No significant associations were observed between ISYNA1 and myo-inositol and glucose, and between SLC39A4 and zinc. A significant interaction was demonstrated between a maternal glucose < 4.5 mmol/L and ISYNA1 1029A > G polymorphism on spina bifida risk.

CONCLUSION

The combination of maternal glucose < 4.5 mmol/L and ISYNA1 1029A > G polymorphism protects against spina bifida offspring. Moreover, maternal SLC5A11 544C > T polymorphism contributes to the serum myo-inositol concentration. Larger studies should confirm these findings.

Low maternal dietary intakes of iron, magnesium, and niacin are associated with spina bifida in the offspring

Evidence about the preventive effects of nutrients other than folate on the occurrence of spina bifida is scarce. Therefore, the aim of this work was to investigate the role of maternal nutritional intake and the risk of spina bifida in the offspring. In 106 cases and 181 controls, the mothers' nutrient intakes were obtained by an FFQ approximately 24 mo after conception of the index pregnancy. Energy-adjusted mean nutrient intakes were compared, and odds ratios (OR) and 95% CI were calculated. Although mean nutrient intakes were comparable to the Dutch food consumption survey data, fat, cholesterol, iron, and folate intakes were below the 1998 Dutch Recommended Daily Allowances. Case mothers had significantly lower intakes of plant proteins (7%), polysaccharides (4%), fiber (7%), iron (6%), magnesium (6%), and niacin (4%) than control mothers. Mono- and disaccharide intakes were significantly higher (6%) in the case mothers than in control mothers. The adjusted OR (95% CI) in the lowest quartiles for plant proteins was 5.4 (2.3-12.4), for fiber 3.1 (1.5-6.8), for iron 3.5 (1.4-8.3), for magnesium 1.9 (0.9-4.1), and for niacin 2.5 (1.2-5.2). Mono- and disaccharide and polysaccharide intakes in the highest quartile had ORs (95% CI) of 2.9 (1.4-6.3) and 0.5 (0.3-1.0), respectively. The nutritional intake of Dutch women from food groups containing iron and folate seems to be compromised. Low preconceptional intakes of plant proteins, iron, magnesium, and niacin are associated with a 2- to 5-fold increased risk of spina bifida.