Gene–nutrient interactions: importance of folates and retinoids during early embryogenesis

In-utero exposure to antibiotics and risk of colorectal cancer in a prospective cohort of 18 000 adult offspring

BACKGROUND

Incidence rates of colorectal cancer (CRC) are increasing among younger adults and in mid-life, implicating exposures in early life as risk factors. We examined the association between in-utero exposure to antibiotics and risk of CRC in adult offspring.

METHODS

The Child Health and Development Studies is a prospective cohort of women receiving prenatal care between 1959 and 1966 in Oakland, California, with deliveries through June 1967. Diagnosed conditions and all prescribed medications were abstracted from mothers' medical records beginning 6 months prior to pregnancy through delivery. We identified mothers who received antibiotics in pregnancy, including penicillins, tetracyclines, short-acting sulfonamides and long-acting sulfonamides. Diagnoses of CRC in adult (age ≥18 years) offspring were ascertained through 2021 by linkage with the California Cancer Registry. Cox proportional models were used to estimate adjusted hazard ratios (aHR), with follow-up accrued from birth through cancer diagnosis, death or last contact.

RESULTS

Of 18 751 liveborn offspring, about 15% (n = 2635) were exposed in utero to antibiotics: 5.4% (n = 1016) to tetracyclines, 4.9% (n = 918) to penicillins, 4.2% (n = 785) to short-acting sulfonamides and 1.5% (n = 273) to long-acting sulfonamides. Compared with offspring not exposed, associations between in-utero exposure and CRC in adult offspring were: aHR 1.03 (95% CI 0.32, 3.31) for tetracyclines; aHR 1.12 (95% CI 0.35, 3.58) for penicillins; aHR 0.83 (95% CI 0.20, 3.42) for short-acting sulfonamides; and aHR 4.40 (95% CI 1.63, 11.88) for long-acting sulfonamides.

CONCLUSION

Our findings support an association between in-utero exposure to long-acting sulfonamides and CRC in adulthood.

Optimizing Maternal Nutrition: The Importance of a Tailored Approach

Improving nutritional status during pregnancy is a global interest. Frequently, women either fail to meet or exceed nutrient recommendations. Current strategies to improve maternal nutrition focus on a "one-size-fits-all" approach and fail to consider individual factors that affect the mother's overall nutritional status. The objectives of this review were to determine the importance of key nutrients for optimal maternal and fetal health, to explore to what extent current recommendations consider individual factors, and to explore novel strategies to close the gap between current guidelines and real-world challenges through more personalized approaches. This review intercalated different nutritional guidelines and recent scientific publications and research initiatives related to maternal nutrition. Based on that, an overview of current recommendations, challenges related to present approaches, and perspectives for future directions are described. Current guidelines are not optimally supporting adequate nutrient intake and health of expectant mothers and their offspring. Existing recommendations are not consistent and do not sufficiently take into account how interindividual variation leads to differences in nutrient status. Personalized nutrition offers women the opportunity to improve their health by using strategies that are tailored to their unique nutritional needs. Such strategies can include personalized supplementation, holistic lifestyle interventions, digital and application-based technologies, and dietary assessment through blood biomarker and genetic analysis. However, these approaches warrant further investigation and optimization. More personalized approaches have the potential to optimize mothers' and their offspring's health outcomes more appropriately to their nutritional needs before, during, and after pregnancy. Moving away from a generalized "one-size-fits-all" approach can be achieved through a variety of means. Future aims should be to provide supporting evidence to create customized subpopulation-based or individualized recommendations, improve nutrition education, and develop novel approaches to improve adherence to dietary and lifestyle interventions.

Periconceptional use of vitamin A and the risk of giving birth to a child with nonsyndromic orofacial clefts-A meta-analysis

BACKGROUND

We conducted a meta-analysis of observational epidemiological studies to evaluate the association between periconceptional use of vitamin A and the risk of giving birth to a child with nonsyndromic orofacial clefts (NSOFCs).

METHODS

We carried out a systematic literature search of Embase, PubMed, Web of Science, Google Scholar, and OpenGrey from inception to June 30, 2021. Two reviewers independently evaluated the studies that met the inclusion criteria and filled out an abstraction form for each study. Study quality was assessed using the Newcastle-Ottawa Assessment Scale (NOS). Adjusted estimates were pooled with an inverse variance weighting using a random-effects model. Heterogeneity and publication bias were assessed using the Cochran's Q test and funnel plot, respectively.

RESULTS

A total of six case-control studies with moderate risk of bias were included. The pooled OR showed a 20% reduction in the risk of NSOFCs for periconceptional use of vitamin A which was not statistically significant (OR = .80; 95% CI .54-1.17, p = .25). For nonsyndromic cleft lip with or without cleft palate (NSCL/P), the studies were homogenous, and the pooled estimate showed a 13% risk reduction, which was significant (OR = .87; 95% CI .77-.99, p = .03). For nonsyndromic cleft palate only (NSCPO), the pooled estimate showed a 33% lower likelihood, which was not statistically significant (OR = .67; 95% CI .42-1.08, p = .10).

CONCLUSION

Our results suggest a possible protective effect for the periconceptional use of vitamin A on the risk of NSCL/P. This finding should be investigated further in prospective studies across multiple populations.

Folic acid supplementation does not decrease stillbirths and congenital malformations in a guide dog colony

OBJECTIVES

To investigate if maternal folic acid supplementation (5 mg) is associated with a reduction of cleft palates, umbilical hernias, stillbirths and caesarean sections in a guide dog breeding colony.

MATERIALS AND METHODS

Labrador retrievers, golden retrievers and Labrador/golden Crosses from the breeding colony of a professional guide dog training organisation were eligible for inclusion. Dams in the treatment group (n = 137) received 5 mg oral folic acid supplementation daily from the start of pro-oestrous through day 40 of gestation. A historical control group (n = 134) was selected from the previous calendar year for comparison. A logistic regression model identified the relative risk of disease (cleft palates, umbilical hernias, stillbirths and caesarean sections) for puppies whose dams did or did not receive folic acid supplementation.

RESULTS

A total of 1917 puppies (890 control, 1027 treatment; from 294 litters) were produced during the entire study period, with 994 puppies (494 control, 500 treatment; from 144 litters) born to the subset of dams (n = 72) who produced litters during both the control and treatment periods. All 95% highest posterior densities of relative risk included 1.0, failing to detect differences between the treatment and control groups on incidence rate of cleft palate (control: 2.25%; treatment: 2.34%), umbilical hernias (control: 1.91%; treatment: 3.12%), stillbirths (control: 3.26%; treatment: 2.92%) and caesarean sections (control: 1.45%; treatment: 1.28%).

CLINICAL SIGNIFICANCE

There was no observable reduction of cleft palate, umbilical hernia, stillbirth or caesarean section associated with folic acid supplementation during pregnancy in the study colony. For a domestic dog cohort with a low tendency of hereditary malformations, such as this study colony, 5 mg dietary folic acid supplementation should not be expected to drastically improve or eradicate these diseases.

Environmental mechanisms of orofacial clefts

Orofacial clefts (OFCs) are among the most common birth defects and impart a significant burden on afflicted individuals and their families. It is increasingly understood that many nonsyndromic OFCs are a consequence of extrinsic factors, genetic susceptibilities, and interactions of the two. Therefore, understanding the environmental mechanisms of OFCs is important in the prevention of future cases. This review examines the molecular mechanisms associated with environmental factors that either protect against or increase the risk of OFCs. We focus on essential metabolic pathways, environmental signaling mechanisms, detoxification pathways, behavioral risk factors, and biological hazards that may disrupt orofacial development.

Non-syndromic Cleft Palate: An Overview on Human Genetic and Environmental Risk Factors

The epithelial and mesenchymal cells involved in early embryonic facial development are guided by complex regulatory mechanisms. Any factor perturbing the growth, approach and fusion of the frontonasal and maxillary processes could result in orofacial clefts that represent the most common craniofacial malformations in humans. The rarest and, probably for this reason, the least studied form of cleft involves only the secondary palate, which is posterior to the incisive foramen. The etiology of cleft palate only is multifactorial and involves both genetic and environmental risk factors. The intention of this review is to give the reader an overview of the efforts made by researchers to shed light on the underlying causes of this birth defect. Most of the scientific papers suggesting potential environmental and genetic causes of non-syndromic cleft palate are summarized in this review, including genome-wide association and gene–environment interaction studies.

Safety and efficacy of supplements in pregnancy

Pregnancy is a time where expectant mothers often focus on their diet to improve their own health and to preserve the future health of their children. There is much conflicting information in the public domain about the safety and/or efficacy of nutritional supplements during pregnancy. Despite this, the market for supplements is growing. This review discusses the roles of critical nutrients in pregnancy and the available evidence on the use of supplements to reduce risks and improve maternal and fetal outcomes. Recommendations are made for pregnant women, taking into account safety data and tolerable upper intakes set for pregnant women. It is important for dieticians, nutritionists, physicians, and other healthcare providers to be able to offer accurate and evidence-based advice on supplement use in pregnancy. Routine supplementation may not be necessary for all, but individuals at risk are identified.

Retinoic Acid Signaling and Heart Development

As the first organ to form and function in all vertebrates, the heart is crucial to development. Tightly-regulated levels of retinoic acid (RA) are critical for the establishment of the regulatory networks that drive normal cardiac development. Thus, the heart is an ideal organ to investigate RA signaling, with much work remaining to be done in this area. Herein, we highlight the role of RA signaling in vertebrate heart development and provide an overview of the field's inception, its current state, and in what directions it might progress so that it may yield fruitful insight for therapeutic applications within the domain of regenerative medicine.

Reiterative Mechanisms of Retinoic Acid Signaling during Vertebrate Heart Development

Tightly-regulated levels of retinoic acid (RA) are critical for promoting normal vertebrate development. The extensive history of research on RA has shown that its proper regulation is essential for cardiac progenitor specification and organogenesis. Here, we discuss the roles of RA signaling and its establishment of networks that drive both early and later steps of normal vertebrate heart development. We focus on studies that highlight the drastic effects alternative levels of RA have on early cardiomyocyte (CM) specification and cardiac chamber morphogenesis, consequences of improper RA synthesis and degradation, and known effectors downstream of RA. We conclude with the implications of these findings to our understanding of cardiac regeneration and the etiologies of congenital heart defects.

Maternal Folic Acid Supplementation and the Risk of Oral Clefts in Offspring

INTRODUCTION

There is controversial evidence from the literature regarding the protective effect of folic acid supplementation during pregnancy against orofacial clefts. The authors undertook this meta-analysis to assess whether folate supplementation during pregnancy can reduce the risk of nonsyndromic cleft lip with or without cleft palate (CL/P) and cleft palate only (CPO) in infants.

METHODS

Eligible articles were identified by searching databases, including PubMed, Medline, Scopus, ISI (Web of Knowledge) to September 2017. A meta-analysis was performed to evaluate the effects of maternal supplementation on oral clefts. Odds ratios (ORs) and 95% confidence intervals (CIs) were pooled using Stata software. Publication bias was assessed by the Begg and Egger test. (Registration ID: CRD42018083922) RESULTS:: Out of the 1630 articles found in the authors' initial literature searches, 6 cohort studies, and 31 case-control studies were included in the authors' final meta-analysis. The results of the main analysis revealed that maternal folate supplementation was associated with a modest but statically significant decreased risk of all cleft subtypes (OR = 0.69, 95% CI: 0.60, 0.78). Folic acid intake alone was inversely associated with CL/P (OR = 0.73, 95% CI: 0.62-0.85,) but to a lesser extent than CPO (OR = 0.75, 95% CI = 053-1.04). Multivitamin intake had a significant protective effect for CL/P (OR = 0.65 95% CI = 0.55-0.80) as well as CPO (OR = 0.69, 95% CI = 0.53-0.90).

CONCLUSIONS

Our results indicate that maternal supplementation in early pregnancy reduces the risk of nonsyndromic CL/P and CPO in infants. These data can serve to reassure women planning a pregnancy to consume multivitamins during the periconception period to protect against oral clefts.

Research: Prevalence of neural tube defects Khartoum, Sudan August 2014-July 2015

Background

Neural tube defects (NTDs) are birth defects that results from failure of the neural tube to develop properly during early pregnancy.

Methods

We studied the prevalence of neural tube defects in newborns admitted to the NICU in Soba University and Omdurman Maternity hospitals, during the period 1st August 2014 to 31st July 2015. A cross-sectional hospital based study, involved all newborns with any type of neural tube defect admitted to the NICU in the study area during the study period. Data was collected using a questionnaire reviewing the medical, social history and clinical examination.

Results

Out of the 36,785 delivered newborns during the study period, the prevalence of NTDs was 2.8:1000. Females were 56 (54.4%) predominated males 47 (45.6%). History of neural tube defects was found in 11 (10.7%) of the affected newborns siblings. Sixty-eight (66%) of the studied mothers received folic acid during pregnancy with the current child, of those who received folic acid 66 (97.1%) started folic acid after conception, 36 (54.5%) in the first trimester and 39 (57.4%) had no regular intake of the folic acid. The types of NTDs include myelomeningocele 49 (47.6%), anencephaly 18 (17.5%), encephalocele 14 (13.6%), myelomeningocele and hydrocephalus 11 (10.7%) and meningocele 8 (7.8%).

Conclusion

The prevalence of neural tube defects is 2.8:1000. Myelomeningocele is the commonest encountered NTD. The use of preconception folic acid needs to be advocated.

The role of folate metabolism in orofacial development and clefting

Folate deficiency has been associated with numerous diseases and birth defects including orofacial defects. However, whether folate has a role in the face during early orofacial development has been unclear. The present study reveals that pharmacological and antisense oligonucleotide mediated inhibition of DHFR, an integral enzyme in the folate pathway, results in specific changes in the size and shape of the midface and embryonic mouth. Such defects are accompanied by a severe reduction in the muscle and cartilage jaw elements without significant change in neural crest pattern or global levels of methylation. We propose that the orofacial defects associated with DHFR deficient function are the result of decreased cell proliferation and increased cell death via DNA damage. In particular, localized apoptosis may also be depleting the cells of the face that express crucial genes for the differentiation of the jaw structures. Folate supplementation is widely known to reduce human risk for orofacial clefts. In the present study, we show that activating folate metabolism can reduce median oral clefts in the primary palate by increasing cell survival. Moreover, we demonstrate that a minor decrease in DHFR function exacerbates median facial clefts caused by RAR inhibition. This work suggests that folate deficiencies could be a major contributing factor to multifactorial orofacial defects.

Maternal obesity and tobacco use modify the impact of genetic variants on the occurrence of conotruncal heart defects

Conotruncal heart defects (CTDs) are among the most severe birth defects worldwide. Studies of CTDs indicate both lifestyle behaviors and genetic variation contribute to the risk of CTDs. Based on a hybrid design using data from 616 case-parental and 1645 control-parental triads recruited for the National Birth Defects Prevention Study between 1997 and 2008, we investigated whether the occurrence of CTDs is associated with interactions between 921 maternal and/or fetal single nucleotide polymorphisms (SNPs) and maternal obesity and tobacco use. The maternal genotypes of the variants in the glutamate-cysteine ligase, catalytic subunit (GCLC) gene and the fetal genotypes of the variants in the glutathione S-transferase alpha 3 (GSTA3) gene were associated with an elevated risk of CTDs among obese mothers. The risk of delivering infants with CTDs among obese mothers carrying AC genotype for a variant in the GCLC gene (rs6458939) was 2.00 times the risk among those carrying CC genotype (95% confidence interval: 1.41, 2.38). The maternal genotypes of several variants in the glutathione-S-transferase (GST) family of genes and the fetal genotypes of the variants in the GCLC gene interacted with tobacco exposures to increase the risk of CTDs. Our study suggests that the genetic basis underlying susceptibility of the developing heart to the adverse effects of maternal obesity and tobacco use involve both maternal and embryonic genetic variants. These results may provide insights into the underlying pathophysiology of CTDs, and ultimately lead to novel prevention strategies.

Interaction between the SLC19A1 gene and maternal first trimester fever on offspring neural tube defects

BACKGROUND

Many studies have indicated that the reduced folate carrier gene (SLC19A1) is associated with an increased risk of neural tube defects (NTDs). However, the interaction between the SLC19A1 gene variant and maternal fever exposure and NTD risk remains unknown. The aim of this study was to investigate whether the risk for NTDs was influenced by the interactions between the SLC19A1 (rs1051266) variant and maternal first trimester fever.

METHODS

We investigated the potential interaction between maternal first trimester fever and maternal or offspring SLC19A1 polymorphism through a population-based case-control study. One hundred and four nuclear families with NTDs and 100 control families with nonmal newborns were included in the study. SLC19A1 polymorphism was determined using polymerase chain reaction-restricted fragment length polymorphism.

RESULTS

Mothers who had the GG/GA genotype and first trimester fever had an elevated risk of NTDs (adjusted odds ratio, 11.73; 95% confidence interval, 3.02-45.58) as compared to absence of maternal first trimester fever and AA genotype after adjusting for maternal education, paternal education, and age, and had a significant interactive coefficient (γ = 3.17) between maternal GG/GA genotype and first trimester fever. However, there was no interaction between offspring's GG/GA genotype and maternal first trimester fever (the interactive coefficient γ = 0.97) after adjusting for confounding factors.

CONCLUSION

Our findings suggested that the risk of NTDs was potentially influenced by a gene-environment interaction between maternal SLC19A1 rs1051266 GG/GA genotype and first trimester fever. Maternal GG/GA genotype may strengthen the effect of maternal fever exposure on NTD risk in this Chinese population.

The role of the folic acid to the prevention of orofacial cleft: an epidemiological study

BACKGROUND

Orofacial clefts (OFCs) have complex and multifactorial etiologies. Periconceptional folic acid supplementation can significantly reduce the risk of OFC.

OBJECTIVE

To evaluate the role of folate and other factors in preventing OFC by analyzing the health and socio-demographic data collected from a population sample.

METHODS

Retrospective case-control study in which mothers with children with or without OFC were evaluated for the following main parameters: nutritional factors, socio-demographic characteristics, pregnancy and family history, use of folate, and counseling by healthcare professionals.

RESULTS

Socio-epidemiological analysis of the 80 participants, 40 in the case group and 40 in the control group, found a significant impact on the risk of OFC related to economic and educational status. The mothers who had a diet rich in vegetables and white meat had a lower risk of having children with OFC. A short interval between pregnancies, subsequent pregnancy while still breastfeeding, and family history also increased risk of OFC.

CONCLUSIONS

Limited family planning, diet low in folate, and inadequate use of folate during the periconceptional period and during the first trimester of pregnancy were demonstrated a potential correlation with a high incidence of OFC in this study.

Descriptive and risk factor analysis for choanal atresia: The National Birth Defects Prevention Study, 1997-2007

Choanal atresia causes serious posterior nasal obstruction. This defect is the leading cause of nasal surgery in newborns, although its etiology is largely unknown. Data from the National Birth Defects Prevention Study, a population-based case-control study, were used to examine associations between maternal self-reports of exposures and occurrence of choanal atresia in their offspring. Overall, 117 case and 8350 control mothers with deliveries from 1997 through 2007 provided telephone interview reports of pre-pregnancy (one year before conception) and periconceptional (one month before through three months after conception) exposures. The exposures analyzed were pre-pregnancy dietary intake, pre-pregnancy and periconceptional caffeine consumption, and periconceptional cigarette smoking, alcohol drinking, and medication use. Independent associations between each exposure and all choanal atresia cases combined (n = 117) and isolated choanal atresia cases (those without additional unrelated major defects; n = 61) were examined. Odds ratios (ORs), both unadjusted (uORs) and adjusted (aORs) for potential confounders, and 95% confidence intervals (CIs) were estimated using unconditional logistic regression analysis. For all choanal atresia cases combined, positive associations were observed with maternal pre-pregnancy intake in the highest quartile for vitamin B-12 (aOR = 1.9; CI = 1.1,3.1), zinc (aOR = 1.7; CI = 1.0,3.1), and niacin (aOR = 1.8; CI = 1.0,3.1), and intake in the lowest quartile for methionine (aOR = 1.6; CI = 1.0,2.6) and vitamin D (aOR = 1.6; CI = 1.0,2.4) compared to intake in the two intermediate quartiles combined. Further, a positive association was observed with periconceptional use of thyroid medications (uOR = 2.6; CI = 1.0,6.3) compared to no use of such medications. Among isolated choanal atresia cases, negative associations were observed for pantothenic acid (aOR = 0.4; CI = 0.2,0.9) and fat (aOR = 0.5; 95% CI = 0.2,1.0) intake in the lowest quartile compared to that in the intermediate quartiles, and positive associations were observed for periconceptional cigarette smoking (aOR = 2.3; CI = 1.1,4.7) compared to no smoking and pre-pregnancy daily coffee intake of 3 or more cups (aOR = 2.5; CI = 1.1,5.6) compared to intake of less than 1 cup per day. The positive association for periconceptional exposure to thyroid medications also persisted for isolated choanal atresia cases (uOR = 4.0; CI = 1.1,11.2). Because of the large number of associations tested, these findings may be due to chance. Alternatively, they may contribute new hypotheses regarding the etiology of choanal atresia; thus, requiring replication in additional studies.

Genetic basis of susceptibility to teratogen induced birth defects

Birth defects remain the leading cause of infant death in US. The field of teratology has been focused on the causes and underlying mechanisms of birth defects for decades, yet our understanding of these critical issues remain unacceptably vague. Conclusions from years of animal and human studies made it clear that the vast majority of birth defects have multifactorial origins, with contributions from environmental and genetic factors. The environment comprises not only of the physical, biological, and chemical external environment surrounding the pregnant woman, but it also includes the internal environment of the woman's body that interact with the developing embryo in a complex fashion. The importance of maternal and embryonic genetic factors consisting of countless genetic variants/mutations that exist within every individual contribute to birth defect susceptibility is only now being more fully appreciated. This great complexity of the genome and its diversity within individuals and populations seems to be the principal reason why the same teratogenic exposure can induce severe malformation in one embryo, while fail to do so to other exposed embryos. As the interaction between genetic and environmental factors has long been recognized as the first "Principle of Teratology" by Wilson and Warkany [1965. Teratology: Principles and techniques. Chicago: University of Chicago Press], it is only recently that the appropriate investigative tools have been developed with which to fully investigate this fundamental principle. The introduction of high throughput technologies like whole genome sequencing or genome-wide association studies are promising to deliver an enormous amount of new data that will shed light on the genomic factors that contribute susceptibility to environmental teratogens. In this review, we attempt to summarize the epidemiological and experimental literature concerning birth defects whose phenotypic expression can be clearly related to the interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. © 2011 Wiley-Liss, Inc.

Nutritional influence on epigenetics and effects on longevity

PURPOSE OF REVIEW

This review synthesizes recently published information regarding nutrition and its impact upon epigenetically mediated mechanisms involved in longevity and aging.

RECENT FINDINGS

Recent studies enriched considerably our understanding of the relationship between aging and gene-nutrient interactions that continuously shape our phenotype. Epigenetic mechanisms play an important role in mediating between the nutrient inputs and the ensuing phenotypic changes throughout our entire life and seem to be responsible, in part, for the biological changes that occur during aging. Less is known about the epigenetic role that nutrients have in directly influencing longevity and aging. However, recent studies clearly indicated that because nutrition modulates epigenetic events associated with various diseases (e.g., cancer, obesity, and diabetes), there is at least an indirect epigenetic link between nutrition and longevity and, therefore, biologic plausibility to hypothesize the epigenetic role of nutrition in altering longevity. Apart from limited human studies, promising animal studies brought us much closer to understanding how nutrition could have such an impact upon longevity and aging.

SUMMARY

Complex epigenetic mechanisms are involved in aging and longevity, directly or indirectly via disease mechanisms. Nutrition has a strong impact upon epigenetic processes and, therefore, holds promise in having important roles in regulating longevity and aging.

Perinatal folate supply: relevance in health outcome parameters

The importance of physiological supply of folate is well recognized in human health; the crucial roles of folate in one-carbon metabolism for physiological DNA synthesis and cell division, as well as in the conversion of homocysteine (Hcy) to methionine, and subsequently, to S-adenosylmethionine, have been convincingly demonstrated. Improved folate status may reduce the risk of macrocytic anaemia, cardiovascular diseases, neuropsychiatric disorders and adverse pregnancy outcomes. Inadequate folate status results in a decrease in the methylation cycle and in increased blood levels of the neurotoxic Hcy. The aim of this review is to provide insight into the influence of folate status on pregnancy health outcomes, and to consider increasing evidence of a link between the extent of genome/epigenome damage and elevated risk for adverse obstetrical endpoints. Pregnant women are at risk for folate insufficiency because of the increased need for folate for rapid fetal growth, placental development and enlargement of the uterus. Inadequate folate status may cause fetal malformations, impaired fetal growth, pre-term delivery and maternal anaemia. Even some diseases of the placenta may arise from folate deficiencies. Fetal growth seems to be vulnerable to maternal folate status during the periconception period, because it has the potential to affect both the closure of the neural tube and several epigenetic mechanisms within the placenta and the fetus. Mainly on the basis of the well recognized link between maternal folate status and fetal neural tube defects, women are advised to receive folic acid supplement during the periconceptional period. Because an adequate folate supply seems to play an important role in the implantation and development of the placenta and in improving endothelial function, folic acid supplementation in the late first trimester or early second trimester might also be beneficial.

A metabonomic approach to analyze the dexamethasone-induced cleft palate in mice

Mice models are an important way to understand the relation between the fetus with cleft palate and changes of maternal biofluid. This paper aims to develop a metabonomics approach to analyze dexamethasone-induced cleft palate in pregnant C57BL/6J mice and to study the relationship between the change of endogenous small molecular metabolites in maternal plasma and the incidence of cleft palate. To do so, pregnant mice were randomly divided into two groups. The one group was injected with dexamethasone. On E17.5th day, the incident rates of cleft palate from embryos in two groups were calculated. The ¹H-NMR spectra from the metabolites in plasma in two groups was collected at same time. Then the data were analyzed using metabonomics methods (PCA and SIMCA). The results showed that the data from the two groups displayed distinctive characters, and the incidence of cleft palate were significantly different (P < .005). To conclude, this study demonstrates that the metabonomics approach is a powerful and effective method in detecting the abnormal metabolites from mother in the earlier period of embryos, and supports the idea that a change from dexamethasone induced in maternal metabolites plays an important role in the incidence of cleft palate.

Genetic variation in the folate metabolic pathway and risk of childhood leukemia

Studies of childhood leukemia and the potential etiologic role of genetic variation in folate metabolism have produced conflicting findings and have often been based on small numbers. We investigated the association between polymorphisms in key folate metabolism enzymes (MTHFR 677 C>T, MTHFR 1298 A>C, SHMT1 1420 C>T, MTR 2756 A>G, TS 1494del6, and TS 28bp repeat) in 939 cases of childhood acute lymphoblastic leukemia (ALL) and 89 cases of acute myeloid leukemia (AML) recruited into the United Kingdom Childhood Cancer Study. We also examined the maternal genotypes of 752 of these cases. Data from 824 noncancer controls recruited were used for comparison. No evidence of an association with MTHFR 677 was observed for ALL or AML, either in children or their mothers. However, in children an increased risk of ALL (odds ratio [OR] = 1.88; 95% confidence interval [CI], 1.16-3.07; P = .010) and AML (OR = 2.74; 95% CI, 1.07-7.01; P = .036) was observed with the MTR 2756 GG genotype; the association was most pronounced for cases with the MLL translocation (OR = 4.90; 95% CI, 1.30-18.45; P = .019). These data suggest that genetic variation in methionine synthase could mediate risk of childhood leukemia, either via effects on DNA methylation or via effects on fetal growth and development.

Cleft lip and palate genetics and application in early embryological development

The development of the head involves the interaction of several cell populations and coordination of cell signalling pathways, which when disrupted can cause defects such as facial clefts. This review concentrates on genetic contributions to facial clefts with and without cleft palate (CP). An overview of early palatal development with emphasis on muscle and bone development is blended with the effects of environmental insults and known genetic mutations that impact human palatal development. An extensive table of known genes in syndromic and non-syndromic CP, with or without cleft lip (CL), is provided. We have also included some genes that have been identified in environmental risk factors for CP/L. We include primary and review references on this topic.

Importance of gene-environment interactions in the etiology of selected birth defects

It is generally understood that both genetic and environmental factors contribute to the highly complex etiology of structural birth defects, including neural tube defects, oral clefts and congenital heart defects, by disrupting highly regulated embryonic developmental processes. The intrauterine environment of the developing embryo/fetus is determined by maternal factors such as health/disease status, lifestyle, medication, exposure to environmental teratogens, as well as the maternal genotype. Certain genetic characteristics of the embryo/fetus also predispose it to developmental abnormalities. Epidemiologic and animal studies conducted over the last few decades have suggested that the interplay between genes and environmental factors underlies the etiological heterogeneity of these defects. It is now widely believed that the study of gene-environment interactions will lead to better understanding of the biological mechanisms and pathological processes that contribute to the development of complex birth defects. It is only through such an understanding that more efficient measures will be developed to prevent these severe, costly and often deadly defects. In this review, we attempt to summarize the complex clinical and experimental literature on current hypotheses of interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. These include maternal folate nutritional status, maternal diabetes/obesity-related conditions, and maternal exposure to selected medications and environmental contaminants. Our goal is to highlight the potential gene-environment interactions affecting early embryogenesis that deserve comprehensive study.

Oral facial clefts and gene polymorphisms in metabolism of folate/one-carbon and vitamin A: a pathway-wide association study

An increased risk of facial clefts has been observed among mothers with lower intake of folic acid or vitamin A around conception. We hypothesized that the risk of clefts may be further moderated by genes involved in metabolizing folate or vitamin A. We included 425 case-parent triads in which the child had either cleft lip with or without cleft palate (CL/P) or cleft palate only (CPO), and no other major defects. We analyzed 108 SNPs and one insertion in 29 genes involved in folate/one-carbon metabolism and 68 SNPs from 16 genes involved in vitamin A metabolism. Using the Triad Multi-Marker (TRIMM) approach we performed SNP, gene, chromosomal region, and pathway-wide association tests of child or maternal genetic effects for both CL/P and CPO. We stratified these analyses on maternal intake of folic acid or vitamin A during the periconceptional period. As expected with this high number of statistical tests, there were many associations with P-values<0.05; although there were fewer than predicted by chance alone. The strongest association in our data (between fetal FOLH1 and CPO, P=0.0008) is not in agreement with epidemiologic evidence that folic acid reduces the risk of CL/P in these data, not CPO. Despite strong evidence for genetic causes of oral facial clefts and the protective effects of maternal vitamins, we found no convincing indication that polymorphisms in these vitamin metabolism genes play an etiologic role.

Preconceptional folic acid supplement use in Lebanon

OBJECTIVE

The objective of the present study was to assess the prevalence and determinants of preconceptional folic acid supplement use among pregnant women in Lebanon.

DESIGN/SETTING/SUBJECTS

The study was a descriptive epidemiological study. Analysis was performed on 5280 deliveries admitted to twelve member hospitals of the National Collaborative Perinatal Neonatal Network during the period September 2003-January 2005. Information on folic acid intake and maternal and neonatal characteristics were obtained from obstetric charts along with direct interviews performed by trained personnel. Logistic regression was performed to determine the predictors of preconceptional folic acid use.

RESULTS

The overall use of preconceptional folic acid supplementation was 14.0 % (18.6 % in urban hospitals v. 2.7 % in rural hospitals). Higher socio-economic status, lower parity and having a history of previous spontaneous abortions were significantly associated with preconceptional folic acid use.

CONCLUSION

Our study shows that Lebanon currently has a low rate of preconceptional folic acid supplement use. Intervention through the means of awareness campaigns needs to be implemented on a national level.

Effect of folic acid on prenatal alcohol-induced modification of brain proteome in mice

Maternal alcohol consumption during pregnancy can induce central nervous system abnormalities in the fetus, and folic acid supplementation can reverse some of the effects. The objective of the present study was to investigate prenatal alcohol exposure-induced fetal brain proteome alteration and the protective effect of folic acid using proteomic techniques. Alcohol (5.0 g/kg) was given intragastrically from gestational day (GD) 6 to 15, with or without 60.0 mg folic acid/kg given intragastrically during GD 1-16 to pregnant Balb/c mice. The control group received distilled water only. Results of litter evaluation on GD 18 showed that supplementation of folic acid reversed the prevalence of microcephaly induced by alcohol. Proteomic analysis indicated that, under the dosage of the present investigation, folic acid mainly reversed the alcohol-altered proteins involved in energy production, signal pathways and protein translation, which are all important for central nervous system development.

Position of the American Dietetic Association: Oral Health and Nutrition

It is the position of the American Dietetic Association that nutrition is an integral component of oral health. The American Dietetic Association supports the integration of oral health with nutrition services, education, and research. Collaboration between dietetics and dental professionals is recommended for oral health promotion and disease prevention and intervention. Scientific and epidemiological data suggest a lifelong synergy between nutrition and the integrity of the oral cavity in health and disease. Oral health and nutrition have a synergistic bidirectional relationship. Oral infectious diseases, as well as acute, chronic, and terminal systemic diseases with oral manifestations, impact the functional ability to eat as well as diet and nutrition status. Likewise, nutrition and diet may affect the development and integrity of the oral cavity as well as the progression of oral diseases. As we advance in our discoveries of the links between oral and nutrition health, practitioners of both disciplines must learn to provide screening, baseline education, and referral to each other as part of comprehensive client/patient care. Dietetics practice requires registered dietitians to provide medical nutrition therapy that incorporates a person's total health needs, including oral health. Inclusion of both didactic and clinical practice concepts that illustrate the role of nutrition in oral health is essential in both dental and dietetic education programs. Collaborative endeavors between dietetics and dentistry in research, education, and delineation of health provider practice roles are needed to ensure comprehensive health care. The multifaceted interactions between diet, nutrition, and oral health in practice, education, and research in both dietetics and dentistry merit continued, detailed delineation.

DNA methylation, riboswitches, and transcription factor activity: fundamental mechanisms of gene-nutrient interactions involving vitamins

Nutrient-gene interactions occur with a variety of nutrients including some minerals, vitamins, polyunsaturated fatty acids and other lipids. Fundamental molecular mechanisms that underlie many of the effects of nutrients on gene expression are presented herein. Two of the mechanisms described influence gene transcription: DNA methylation and transcription factor activation. Another mechanism, riboswitching, can regulate gene expression at different levels, for example, at the mRNA translation level. The first two mechanisms are widely distributed across animal phyla. Riboswitches are documented primarily in more primitive organisms, but may prove to be of wider relevance. Riboswitches are known for several vitamins; those involving thiamine are presented here. The role of folates and retinoids in DNA methylation and transcriptional factor (nuclear retinoid receptor) activities, respectively, is presented in the context of cell proliferation and differentiation, and related physiological or pathological effects during embryogenesis and cancer.

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.

The impact of plasma folate levels of mothers and newborns on intrauterine growth retardation and birth weight

Folate plays an important role in the genomic stability of human cells. In our studies of the impact of environmental pollution on human health, we have found that air pollution can affect pregnancy outcome. As it may be also affected by nutrition, we examined the effect of plasma folate levels of mothers and newborns on intrauterine growth retardation (IUGR) and birth weight (BW) in cohorts from Prague (N=319) and Teplice (N=444). The lower plasma levels (<6.1 nmol/L) were observed in 7.1% of mothers in Prague, and in 9.6% of mothers in Teplice. The higher plasma levels (>36.5 nmol/L) were observed in 28.4% of mothers in Prague, and in 15.7% of mothers in Teplice. The higher plasma levels were observed in 75.4% of newborns in Prague, and 73.2% of newborns in Teplice. When comparing maternal high versus low folate plasma levels and IUGR by logistic regression, the risk of IUGR was significantly decreased for European cohort (according to ethnicity) with gestation age >36 weeks [N=536, OR=0.44, P=0.026], and even more pronounced in the group of European smokers [N=157, OR=0.14, P=0.015]. Using multiple regression analysis, plasma folate levels of mothers and newborns significantly affected the birth weight of newborns of smoking mothers (P<0.05). The obtained results seem to indicate a positive effect of folate on pregnancy outcome, especially its potential to decrease the risk of IUGR in European population and lower birth weight in smoking European mothers. It would be warranted to study the effect of folate levels on pregnancy outcomes in the relationship to different environmental pollution and life styles of mothers.

Orofacial clefting: recent insights into a complex trait

Orofacial clefts are common birth defects of multifactorial etiology. Several novel approaches have recently been applied to investigate the causes of clefts. These include examining Mendelian forms of clefting to identify genes that might also be implicated in isolated clefting, analyzing chromosomal rearrangements in which clefting is part of the resultant phenotype, studying animal models in which clefts arise either spontaneously or as a result of mutagenesis experiments, exploring how expression patterns correlate with gene function and examining the effects of gene-environment interactions. Together, these complementary strategies are providing researchers with new clues as to what mechanisms underlie orofacial clefting.

Investigations into the etiology of neural tube defects

Neural tube defects (NTDs) are serious malformations affecting approximately 1 per 1000 births, yet the mechanisms by which they arise are unknown. There have been consistent efforts in many fields of research to elucidate the etiology of this multifactorial condition. While no single gene has been identified as a major independent risk factor for NTDs, candidate genes have been proposed that may modify the effects of maternal and/or embryonic exposures. Folate supplementation effectively reduces the occurrence of NTDs and, consequently, has focused much research on metabolism of folate-related pathways during pregnancy and development. Further understanding of normal development and how teratogens can perturb these orchestrated processes also remains at the fore of modern scientific endeavors. The composite of these factors remains fragmented; the aim of this review is to provide the reader with a summary of sentinel and current works in the body of literature addressing NTD disease etiology.