Oral clefts and vitamin supplementation

A Systematic Literature Review on the Association Between Toxic and Essential Trace Elements and the Risk of Orofacial Clefts in Infants

Orofacial clefts (OFCs) have been linked to various toxic and essential trace elements (TETEs) worldwide. However, review estimation is absent. Therefore, addressing the hypothesis that TETEs are associated with OFCs is the main area of this review. A systematic literature search was conducted using electronic databases through PubMed, Web of Science, Scopus, Science Direct, and Google Scholar between 2004 and August 2022. The "AND" and "OR" operators were used to make our search results inclusive and restrictive as follows: ("Toxic element*" OR "Heavy metal*") AND ("Toxic element*" OR "Lead OR Arsenic OR Mercury*")) AND ("Essential trace element*" OR "Zinc OR Selenium OR Copper*")) AND ("Orofacial cleft*" OR "Cleft lip*" OR "Cleft palate*") AND ("Infant*" OR "Newborn*" OR "Neonate*")). The presence of toxic elements was linked to the development of OFCs. The results showed that higher levels of toxic elements in various biological sample types were related to increased risks for OFCs. Increased concentrations of essential trace elements (ETEs) lowered the risk of OFCs. Maternal consumption of diets rich in ETEs, including zinc (Zn), selenium (Se), copper (Cu), cobalt (Co), and molybdenum (Mo), was linked to a more pronounced reduction in the risk of OFCs. Based on the findings, it is acceptable to infer that maternal exposure to toxic elements, whether through environmental contaminants or dietary sources, was associated with an elevated risk of OFCs. Furthermore, the study revealed that ETEs exhibited a potential protective role in reducing the incidence of OFCs. This observation highlights the importance of reducing exposure to toxic elements during pregnancy and suggests that optimizing maternal intake of ETEs could be an effective preventive strategy.

Analysis of Gut Characteristics and Microbiota Changes with Maternal Supplementation in a Neural Tube Defect Mouse Model

Adequate nutrient supply is crucial for the proper development of the embryo. Although nutrient supply is determined by maternal diet, the gut microbiota also influences nutrient availability. While currently there is no cure for neural tube defects (NTDs), their prevention is largely amenable to maternal folic acid and inositol supplementation. The gut microbiota also contributes to the production of these nutrients, which are absorbed by the host, but its role in this context remains largely unexplored. In this study, we performed a functional and morphological analysis of the intestinal tract of loop-tail mice (Vangl2 mutants), a mouse model of folate/inositol-resistant NTDs. In addition, we investigated the changes in gut microbiota using 16S rRNA gene sequencing regarding (1) the host genotype; (2) the sample source for metagenomics analysis; (3) the pregnancy status in the gestational window of neural tube closure; (4) folic acid and (5) D-chiro-inositol supplementation. We observed that Vangl2+/Lp mice showed no apparent changes in gastrointestinal transit time or fecal output, yet exhibited increased intestinal length and cecal weight and gut dysbiosis. Moreover, our results showed that the mice supplemented with folic acid and D-chiro-inositol had significant changes in their microbiota composition, which are changes that could have implications for nutrient absorption.

Gene×environment associations in orofacial clefting

This chapter reviews the evidence of gene×environment interactions (G×E) in the etiology of orofacial cleft birth defects (OFCs), specifically cleft lip (CL), cleft palate (CP), and cleft lip with or without cleft palate (CL/P). We summarize the current state of our understanding of the genetic architecture of nonsyndromic OFCs and the evidence that maternal exposures during pregnancy influence risk of OFCs. Further, we present possible candidate gene pathways for these exposures including metabolism of folates, metabolism of retinoids, retinoic acid receptor signaling, aryl hydrocarbon receptor signaling, glucocorticoid receptor signaling, and biotransformation and transport. We review genes in these pathways with prior evidence of association with OFCs, genes with evidence from prior candidate gene G×E studies, and genes identified from genome-wide searches specifically for identifying G×E. Finally, we suggest future directions for G×E research in OFCs.

Poverty and Risk of Cleft Lip and Palate: An Analysis of United States Birth Data

BACKGROUND

The relationship between poverty and incidence of cleft lip and cleft palate remains unclear. The authors investigated the association between socioeconomic status and cleft lip with or without cleft palate and cleft palate only in the United States after controlling for demographic and environmental risk factors.

METHODS

The U.S. 2016 and 2017 natality data were utilized. Proxies for socioeconomic status included maternal education, use of the Special Supplemental Nutrition Program for Women, Infants, and Children, and payment source for delivery. Multiple logistic regression controlled for household demographics, prenatal care, maternal health, and infant characteristics.

RESULTS

Of 6,251,308 live births included, 2984 (0.05 percent) had cleft lip with or without cleft palate and 1180 (0.02 percent) had cleft palate only. Maternal education of bachelor's degree or higher was protective against, and delayed prenatal care associated with, cleft lip with or without cleft palate (adjusted ORs = 0.73 and 1.14 to 1.23, respectively; p < 0.02). Receiving assistance under the Special Supplemental Nutrition Program for Women, Infants, and Children was associated with cleft palate only (adjusted OR = 1.25; p = 0.003). Male sex, first-trimester tobacco smoking, and maternal gestational diabetes were also associated with cleft lip with or without cleft palate (adjusted ORs = 1.60, 1.01, and 1.19, respectively; p < 0.05). Female sex, prepregnancy tobacco smoking, and maternal infections during pregnancy were associated with cleft palate only (adjusted ORs = 0.74, 1.02, and 1.60, respectively; p < 0.05).

CONCLUSIONS

Increased incidence of orofacial clefts was associated with indicators of lower socioeconomic status, with different indicators associated with different cleft phenotypes. Notably, early prenatal care was protective against the development of cleft lip with or without cleft palate.

CLIINCAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Gestational folate deficiency alters embryonic gene expression and cell function

Folic acid is a nutrient essential for embryonic development. Folate deficiency can cause embryonic lethality or neural tube defects and orofacial anomalies. Folate receptor 1 (Folr1) is a folate binding protein that facilitates the cellular uptake of dietary folate. To better understand the biological processes affected by folate deficiency, gene expression profiles of gestational day 9.5 (gd9.5) Folr1^-/- embryos were compared to those of gd9.5 Folr1^+/+ embryos. The expression of 837 genes/ESTs was found to be differentially altered in Folr1^-/- embryos, relative to those observed in wild-type embryos. The 837 differentially expressed genes were subjected to Ingenuity Pathway Analysis. Among the major biological functions affected in Folr1^-/- mice were those related to 'digestive system development/function', 'cardiovascular system development/function', 'tissue development', 'cellular development', and 'cell growth and differentiation', while the major canonical pathways affected were those associated with blood coagulation, embryonic stem cell transcription and cardiomyocyte differentiation (via BMP receptors). Cellular proliferation, apoptosis and migration were all significantly affected in the Folr1^-/- embryos. Cranial neural crest cells (NCCs) and neural tube explants, grown under folate-deficient conditions, exhibited marked reduction in directed migration that can be attributed, in part, to an altered cytoskeleton caused by perturbations in F-actin formation and/or assembly. The present study revealed that several developmentally relevant biological processes were compromised in Folr1^-/- embryos.

Maternal exposures and risk of oral clefts in South Vietnam

BACKGROUND

Oral clefts are among the most common congenital anomalies. Most studies on risk factors of oral clefts have been carried out in developed countries. We investigated the associations between maternal exposures in the first trimester and oral clefts in South Vietnam.

METHODS

We conducted a hospital-based case-control study during October 2014-November 2015. Cases included 170 patients with nonsyndromic cleft lip with or without cleft palate and those with cleft palate only. Controls were 170 children without oral clefts, matched to each case by age and gender. Mothers were interviewed using structured questionnaire. We performed conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Passive smoking was associated with increased risk of oral clefts in univariate analysis, but not in multivariable analysis (adjusted OR [aOR] = 1.68; 95% CI, 0.53-5.37). No association was observed between liver intake and oral clefts. Compared with nondrinkers, mothers who reported consumption of caffeine-containing beverages were more likely to have an infant with oral cleft (aOR = 5.89; 95% CI, 1.08-32.00). Periconceptional use of folic acid and multivitamins supplementation was associated with reduced risk of oral clefts (aOR = 0.01; 95% CI, 0.00-0.09 and aOR = 0.03; 95% CI, 0.01-0.13, respectively).

CONCLUSIONS

The results suggest no associations of maternal passive smoking or liver intake with oral clefts. Periconceptional use of folic acid or multivitamins may protect against oral clefts. Further studies are warranted to examine the roles of caffeine consumption in pregnant mothers on occurrence of oral clefts in offspring.

Strong Association of C677T Polymorphism of Methylenetetrahydrofolate Reductase Gene With Nosyndromic Cleft Lip/Palate (nsCL/P)

Methylenetetrahydrofolate reductase (MTHFR) is essential for DNA biosynthesis and the epigentic process of DNA methylation. It has been reported that abnormal DNA methylation contributes to the pathogenesis of congenital anomalies. There were many published case control studies assessing the associations of MTHFR C677T polymorphism with risks of nosyndromic cleft lip with and without palate (nsCL/P), but with inconsistent results. To derive a more precise estimation of the relationship, a meta-analysis was performed. Eligible articles were identified by search of databases including PubMed, Science Direct, Google Scholar and Springer Link up to December, 2015. Finally, a total of 22 studies with 3724 nsCL/P cases and 5275 controls were included in the present meta-analysis. Odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) were pooled to assess the association. Subgroup analysis based on ethnicity was also performed. All statistical analyses were done by MIX program. Meta-analysis results suggested that MTHFR C677T polymorphism contributed to the increased nsCL/P risk in overall population using four genetic models except homozygote model (for T vs. C: OR = 1.24, 95% CI = 1.1-1.4; for TT + CT vs. CC: OR = 1.29, 95% CI = 1.04-1.59; for CT vs. CC: OR = 1.26, 95% CI = 0.98-1.63; for TT vs. CC: OR = 1.02, 95% CI = 0.74-1.4; for TT vs. CT + CC: OR = 1.36, 95% CI = 1.05-1.74). In conclusion, results of present meta-analysis suggested that MTHFR C677T polymorphism is significantly associated with nonsyndromic orofacial cleft.

Case-control study of nutritional and environmental factors and the risk of oral clefts in Thailand

BACKGROUND

One infant in 700 is born with an oral cleft. Prior studies suggest low micronutrient status is associated with an increased risk of oral clefts. Environmental factors such as passive smoke exposure or supplement use may also affect oral cleft risk. We examined nutrition and environmental related risk factors for oral clefts.

METHODS

We conducted a case-control study in Northeast Thailand in 2012 to 2013. We enrolled 95 cases and 95 controls. We recruited cases with a nonsyndromic cleft lip with or without a cleft palate (CL±P) less than 24 months old. Cases were matched to controls on age and place of conception. We collected survey data, a food frequency questionnaire, and measured zinc concentrations in toenail trimmings. We calculated descriptive statistics by case and control status. We used conditional logistic regression to estimate unadjusted and adjusted associations, 95% confidence intervals (CIs), and p-values.

RESULTS

Any liver intake (adjusted OR [aOR] for ≥1/week versus none), 10.58; 95%CI, 1.74-64.37, overall p = 0.02) and the presence of food insecurity (aOR, 9.62; 95% CI, 1.52-61.05; p = 0.02) in the periconceptional period increased CL±P risk. Passive smoke exposure increased the risk of CL±P (aOR, 6.52; 95% CI, 1.98-21.44; p < 0.01). Toenail zinc concentrations were not associated with CL±P risk.

CONCLUSION

Our findings add to a growing body of knowledge of environmental risk factors for oral clefts from low- and middle-income countries. Our findings on liver are contradictory to prior results. Large multisite studies are needed to identify environmental and genetic risk factors for oral clefts. Birth Defects Research (Part A) 106:624-632, 2016. © 2016 Wiley Periodicals, Inc.

Evaluation of proton-coupled folate transporter (SLC46A1) polymorphisms as risk factors for neural tube defects and oral clefts

Many folate-related genes have been investigated for possible causal roles in neural tube defects (NTDs) and oral clefts. However, no previous reports have examined the major gene responsible for folate uptake, the proton-coupled folate transporter (SLC46A1). We tested for association between these birth defects and single nucleotide polymorphisms in the SLC46A1 gene. The NTD study population included 549 complete and incomplete case-family triads, and 999 controls from Ireland. The oral clefts study population comprised a sample from Utah (495 complete and incomplete case-family triads and 551 controls) and 221 Filipino multiplex cleft families. There was suggestive evidence of increased NTD case risk with the rs17719944 minor allele (odds ratio (OR): 1.29; 95% confidence intervals (CI): [1.00-1.67]), and decreased maternal risk of an NTD pregnancy with the rs4795436 minor allele (OR: 0.62; [0.39-0.99]). In the Utah sample, the rs739439 minor allele was associated with decreased case risk for cleft lip with cleft palate (genotype relative risk (GRR): 0.56 [0.32-0.98]). Additionally, the rs2239907 minor allele was associated with decreased case risk for cleft lip with cleft palate in several models, and with cleft palate only in a recessive model (OR: 0.41; [0.20-0.85]). These associations did not remain statistically significant after correcting for multiple hypothesis testing. Nominal associations between SLC46A1 polymorphisms and both Irish NTDs and oral clefts in the Utah population suggest some role in the etiology of these birth defects, but further investigation in other populations is needed.

Cleft lip and palate and related factors: A 10 years study in university hospitalised patients at Mashhad--Iran

BACKGROUND

Oral-facial clefts including cleft lip and palate are the most common congenital malformations of the head and neck. Environmental factors such as maternal hormonal disorders, use of psychiatric medications, vitamin and folic acid deficiency, hypoxia, cigarette smoking and maternal obesity and overweight can affect the incidence of these disorders. In Iran, one of the associated problems is a lack of accurate statistics regarding the present status of the patients, which can cause a disturbance in the health programmes of Ministry of Health and Medical Education. The aim of this study was to report the status of 398 cases of cleft lip and palate in Sheikh and Imam Reza Hospitals of Mashhad over a 10-year period.

MATERIALS AND METHODS

This retrospective descriptive study was performed using data collection method and included the evaluation of the recorded files and completing the data forms. In this study, the file records of 398 patients referring to Mashhad Sheikh and Imam Reza (P.U.H) Hospitals were studied, from the beginning of 2002 to the end of 2011; the obtained data from the files were collected and classified.

RESULTS

The highest frequency was related to cleft palate alone (40.7%); frequencies were lower regarding the cleft lip and palate and cleft lip alone (34.41% and 24.87%, respectively). Approximately, half of the patients were from rural areas of the city and had articulation disorders. Most of the patients were the first-born children of the family and their parents were consanguineously married; about one-third of the patients had a family history of the disease.

CONCLUSION

According to the results of the present study, cleft lip is more frequent in males and cleft palate is more prevalent in females; the obtained results are consistent with the global statistics.

CLEFT PALATE IN HIV-EXPOSED NEWBORNS OF MOTHERS ON HIGHLY ACTIVE ANTIRETROVIRAL THERAPY

AIMS

Cleft lip/palate, though rare, is the commonest head and neck congenital malformation. Both genetic and environmental factors have been implicated in the aetiopathogenesis but the role of in-utero exposure to human immunodeficiency virus (HIV) and highly active antiretroviral therapy (HAART) is still being investigated. This short communication reports the occurrence of cleft palate in three newborns exposed in-utero to HIV and HAART.

MATERIAL AND METHODS

This is a case series of HIV-exposed newborns observed to have cleft palate among a larger cohort of HIV-exposed and unexposed newborns in a study evaluating the effect of HIV infection and HAART on newborn hearing. The Risk Ratio (RR) was calculated to detect a potential association between in-utero exposure to Efavirenz containing ART and cleft palate.

RESULTS

Three HIV-exposed newborns with cleft palate were identified during hearing screening performed on 126 HIV-exposed and 121 HIV unexposed newborns. Two had exposure to tenofovir+lamivudine+efavirenz (TDF+3TC+EFV) while the third had exposure to zidovudine+lamivudine+nevirapine (ZDV+3TC+NVP) during the first trimester. There was no statistically significant association between presence of cleft palate and exposure to an EFV containing HAART regimen (p=0.07, RR=10.95 [0.94-126.84]).

CONCLUSIONS

This communication highlights the possible aetiologic role of HAART in cleft palate, the need for further prospective follow-up studies and establishment of antiretroviral pregnancy, birth and neonatal registries.

Micronutrients and oral clefts: a case-control study

Little is known about oral clefts in developing countries. We aimed to identify micronutrient-related and environmental risk factors for oral clefts in Thailand. We tested hypotheses that maternal exposure during the periconceptional period to multivitamins or liver consumption would decrease cleft lip with or without cleft palate (CL ± P) risk and that menstrual regulation supplements would increase CL ± P risk. We conducted a multisite hospital-based case-control study in Thailand. We enrolled cases with CL ± P and 2 live births as controls at birth from the same hospital. Mothers completed a questionnaire. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Eighty-six cases and 172 controls were enrolled. Mothers who took a vitamin (adjusted OR, 0.39; 95% CI: 0.16, 0.94) or ate liver (adjusted OR, 0.26; 95% CI: 0.12, 0.57) were less likely than those who did not to have an affected child. Mothers who took a menstrual regulation supplement were more likely than mothers who did not to have an affected child. Findings did not differ for infants with a family history of other anomalies or with isolated CL ± P. If replicated, our finding that liver decreases CL ± P risk could offer a low-cost primary prevention strategy.

Association between CDH1 and MSX1 Gene Polymorphisms and the Risk of Nonsyndromic Cleft Lip and/or Cleft Palate in a Southeast Iranian Population

Objective

Orofacial clefts such as cleft palate (CP) and cleft lip (CL) and/or cleft palate (CL/P) are the most common congenital anomalies of the head and neck. The aims of the present study were to evaluate the possible association between CDH1 (rs11642413 and rs16260) and MSX1 (rs12532 and rs3775261) gene polymorphisms and nonsyndromic cleft lip and/or cleft palate (NS-CL/P) in a sample of the Iranian population.

Design and Setting

This case-control study was performed on 100 subjects with NS-CL/P and 100 healthy unrelated control subjects. Tetra amplification refractory mutation system-polymerase chain reaction and multiplex polymerase chain reaction were used to detect the single-nucleotide polymorphisms.

Results

There was a significant difference between NS-CL/P subjects and control subjects regarding CDH1 rs16260 C > A polymorphism, and the rs16260 AC as well as the rs16260 AA genotypes were associated with NS-CL/P susceptibility (odds ratio [OR] = 3.02, 95% confidence interval [CI] =1.51 −6.00, P=.001; and OR = 8.05, 95% CI = 1.72–37.75, P=.002, respectively). No significant difference was found between the groups regarding CDH1 rs11642413 polymorphism. Although MSX1 rs3775261 polymorphism was not a risk factor for the disease, the rs12532 AG and rs12532 GG genotypes were associated with NS-CL/P risk (OR = 2.82, 95% CI = 1.55–5.15, P=.001; and OR = 8.42, 95% CI = 2.26–31.29, P=.004, respectively).

Conclusion

Our data suggest that CDH1 and MSX1 gene polymorphisms are risk factors for susceptibility to NS-CL/P in a sample of the Iranian population. Larger studies are required to validate our findings.

Prevention of oro-facial clefts in developing world

Oro-facial cleft (OFC) remains a prominent health issue in developed and developing countries alike. It is the commonest craniofacial birth defect in humans. Mounting evidence suggest a polygenic, multifactorial and a list of epigenetic events. Primary prevention of OFC is based on recognition of the etiologic and risk factors. While a number of preventive strategies are in place for OFC in most developed countries of the world, the majority of developing countries are distant from achieving this goal for a number of reasons. Notable among these are a huge knowledge and practice gap in the field of genetics and dearth of accurate data. In addition, improper coordination and absenteeism from antenatal care contributed greatly to this set back. With ongoing efforts aimed at determining the genetics of nonsyndromic OFC in developing countries, researches directed at identifying environmental factors should equally be in place. Pending the outcome of these, implicated environmental and attitudinal risk factors in other populations could serve as preventive template in health education and interventions. Since risk factors vary between populations, definitive and effective preventive strategies and models would vary from place to place and from time to time. Frantic effort directed at identifying specific implicated risk factors in developing countries should include developing and keeping comprehensive national perinatal database and centralization of antenatal care protocol. Additionally, active health education at every level and a focus on developing manpower in the field of genetics should be in place. These would be designed and tailored toward identified, proven, and emerging risk factors.

Maternal diet supplementation with methyl donors and increased parity affect the incidence of craniofacial defects in the offspring of twisted gastrulation mutant mice

Diets rich in methyl-donating compounds, including folate, can provide protection against neural tube defects, but their role in preventing craniofacial defects is less clear. Mice deficient in Twisted gastrulation (TWSG1), an extracellular modulator of bone morphogenetic protein signaling, manifest both midline facial defects and jaw defects, allowing study of the effects of methyl donors on various craniofacial defects in an experimentally tractable animal model. The goal of this study was to examine the effects of maternal dietary supplementation with methyl donors on the incidence and type of craniofacial defects among Twsg1(-/-) offspring. Nulliparous and primiparous female mice were fed an NIH31 standard diet (control) or a methyl donor supplemented (MDS) diet (folate, vitamin B-12, betaine, and choline). Observed defects in the pups were divided into those derived mostly from the first branchial arch (BA1) (micrognathia, agnathia, cleft palate) and midline facial defects in the holoprosencephaly spectrum (cyclopia, proboscis, and anterior truncation). In the first pregnancy, offspring of mice fed the MDS diet had lower incidence of BA1-derived defects (12.8% in MDS vs. 32.5% in control; P = 0.02) but similar incidence of midline facial defects (6.4% in MDS vs. 5.2% in control; P = 1.0). Increased maternal parity was independently associated with increased incidence of craniofacial defects after adjusting for diet (from 37.7 to 59.5% in control, P = 0.04 and from 19.1 to 45.3% in MDS, P = 0.045). In conclusion, methyl donor supplementation shows protective effects against jaw defects, but not midline facial defects, and increased parity can be a risk factor for some craniofacial defects.

Oral cleft prevention program (OCPP)

Background

Oral clefts are one of the most common birth defects with significant medical, psychosocial, and economic ramifications. Oral clefts have a complex etiology with genetic and environmental risk factors. There are suggestive results for decreased risks of cleft occurrence and recurrence with folic acid supplements taken at preconception and during pregnancy with a stronger evidence for higher than lower doses in preventing recurrence. Yet previous studies have suffered from considerable design limitations particularly non-randomization into treatment. There is also well-documented effectiveness for folic acid in preventing neural tube defect occurrence at 0.4 mg and recurrence with 4 mg. Given the substantial burden of clefting on the individual and the family and the supportive data for the effectiveness of folic acid supplementation as well as its low cost, a randomized clinical trial of the effectiveness of high versus low dose folic acid for prevention of cleft recurrence is warranted.

Methods/design

This study will assess the effect of 4 mg and 0.4 mg doses of folic acid, taken on a daily basis during preconception and up to 3 months of pregnancy by women who are at risk of having a child with nonsyndromic cleft lip with/without palate (NSCL/P), on the recurrence of NSCL/P. The total sample will include about 6,000 women (that either have NSCL/P or that have at least one child with NSCL/P) randomly assigned to the 4 mg and the 0.4 mg folic acid study groups. The study will also compare the recurrence rates of NSCL/P in the total sample of subjects, as well as the two study groups (4mg, 0.4 mg) to that of a historical control group.

The study has been approved by IRBs (ethics committees) of all involved sites. Results will be disseminated through publications and presentations at scientific meetings.

Discussion

The costs related to oral clefts are high, including long term psychological and socio-economic effects. This study provides an opportunity for huge savings in not only money but the overall quality of life. This may help establish more specific clinical guidelines for oral cleft prevention so that the intervention can be better tailored for at-risk women.

ClinicalTrials.gov Identifier

NCT00397917

Folic acid use and nonsyndromic orofacial clefts in China: a prospective cohort study

BACKGROUND

Questions remain about the effectiveness, dose, and timing of folic acid in preventing orofacial clefts. Case-control studies report conflicting results. There have been no cohort studies of orofacial clefts and the use of folic acid without other vitamins.

METHODS

In a prospective cohort of 240,244 women enrolled between 1993 and 1995 in 1 northern and 2 southern provinces in China, we examined the risk of nonsyndromic cleft lip with or without cleft palate (CL/P) and cleft palate alone (CP) in relation to maternal use of 400 μg of folic acid without other vitamins.

RESULTS

Daily use of 400 μg of folic acid without other vitamins, started before the last menstrual period (LMP), was associated with reduced risk of CL/P with adjusted rate ratio (aRR) of 0.69 (95% confidence interval = 0.55-0.87). The greatest reduction in risk was observed in the north among daily users who began taking folic acid pills before LMP (aRR = 0.21 [0.10-0.44]); in the south there was marginal reduction in risk (aRR = 0.81 [0.63-1.05]). No evidence of reduced CL/P risk was observed among women who started folic acid pills on or after their LMP. No persuasive evidence for reduction in CP risk was seen with folic acid pill use at any time.

CONCLUSION

Daily maternal consumption of 400 μg of folic acid without other vitamins, started before mother's LMP, was associated with a reduced risk of CL/P in babies born in a high-prevalence region of China.

Effect of women's nutrition before and during early pregnancy on maternal and infant outcomes: a systematic review

Current understanding of biologic processes indicates that women's nutritional status before and during early pregnancy may play an important role in determining early developmental processes and ensuring successful pregnancy outcomes. We conducted a systematic review of the evidence for the impact of maternal nutrition before and during early pregnancy (<12 weeks gestation) on maternal, neonatal and child health outcomes and included 45 articles (nine intervention trials and 32 observational studies) that were identified through PubMed and EMBASE database searches and examining review articles. Intervention trials and observational studies show that periconceptional (<12 weeks gestation) folic acid supplementation significantly reduced the risk of neural tube defects. Observational studies suggest that preconceptional and periconceptional intake of vitamin and mineral supplements is associated with a reduced risk of delivering offspring who are low birthweight and/or small-for-gestational age (SGA) and preterm deliveries (PTD). Some studies report that indicators of maternal prepregnancy size, low stature, underweight and overweight are associated with increased risks of PTD and SGA. The available data indicate the importance of women's nutrition prior to and during the first trimester of pregnancy, but there is a need for well-designed prospective studies and controlled trials in developing country settings that examine relationships with low birthweight, SGA, PTD, stillbirth and maternal and neonatal mortality. The knowledge gaps that need to be addressed include the evaluation of periconceptional interventions such as food supplements, multivitamin-mineral supplements and/or specific micronutrients (iron, zinc, iodine, vitamin B-6 and B-12) as well as the relationship between measures of prepregnancy body size and composition and maternal, neonatal and child health outcomes.

Antiretroviral Prophylaxis and the Risk of Cleft Lip and Palate: Preliminary Signal Detection in the Food and Drug Administration's Adverse Events Reporting System Database

Objective

Antiretroviral prophylaxis has been found to be effective in preventing vertical HIV transmission to the offspring of infected mothers. Because medicine and the art of public health require benefits to outweigh any plausible risks, our study aimed to explore and quantify preliminary associations between antiretroviral medications and clefting.

Methods

We analyzed 5 years of available data from the Food and Drug Administration's Adverse Events Reporting System (Medwatch program) and calculated reporting odds ratios (RORs) and their associated 95% confidence intervals (CIs).

Results

The medications with the highest effects were efavirenz with an ROR of 196 (95% CI, 86 to 447), lamivudine with an ROR of 60.2 (95% CI, 14.25 to 148), the combination abacavir sulfate/lamivudine/zidovudine with an ROR of 59.3, and nelfinavir with and ROR of 50.5, followed by nevirapine, lopinavir/ritonavir, and lamivudine/zidovudine.

Conclusion

Given the multifactorial etiology of cleft lip and palate, further studies are needed to assess the relative safety of antiretroviral prophylaxis and the specific conditions or potential synergies that might lead to the development of this defect.

Enlarged nuchal translucency in chromosomally normal fetuses: strong association with orofacial clefts

OBJECTIVES

The aim of this study was to investigate whether there is an association between enlarged nuchal translucency (NT) and orofacial clefts.

METHODS

The pregnancy outcome of women who underwent an NT measurement between January 2000 and November 2008 was reviewed. All orofacial clefts detected prenatally and postnatally in karyotypically normal fetuses/infants were reviewed and a distinction was made between isolated defects and clefts as part of multiple congenital anomalies (associated).

RESULTS

The cohort included 8638 fetuses. The NT was enlarged in 746 (8.6%). The karyotype was normal in 8347 fetuses, including 513 of the fetuses with an enlarged NT. Isolated or associated cleft lip, with or without cleft palate (CL/P), or cleft palate (CP) were diagnosed in 18 chromosomally normal fetuses (an incidence of 2.2 per 1000). In eight of these cases the NT was normal (8/7834; an incidence of 1.0 per 1000) and in the remaining 10 it was enlarged (10/513; an incidence of 19.5 per 1000). CL/P and CP were isolated or associated in three and seven of the chromosomally normal fetuses with an enlarged NT, respectively. Euploid fetuses with an enlarged NT had a relative risk for any clefts of 19 and a relative risk for isolated or associated clefts of 8 and 53, respectively (P < 0.001).

CONCLUSIONS

Chromosomally normal fetuses with an enlarged NT have an increased risk of orofacial clefts. CL/P and CP are, in these fetuses, mostly associated findings, frequently part of a genetic syndrome. A detailed ultrasound examination with special attention given to the orofacial area is indicated in these fetuses.

Folic acid in early pregnancy: a public health success story

Folate is a water-soluble B vitamin that must be obtained in the diet or through supplementation. For >50 yr, it has been known that folate plays an integral role in embryonic development. In mice, inactivation of genes in the folate pathway results in malformations of the neural tube, heart, and craniofacial structures. It has been shown that diets and blood levels of women who had a fetus with a neural tube defect are low for several micronutrients, particularly folate. Periconceptional use of folic acid containing supplements decreased recurrent neural tube defects in the offspring of women with a previously affected child and the occurrence of a neural tube defect and possibly other birth defects in the offspring of women with no prior history. Based on these findings, the U.S. Public Health Service recommended that all women at risk take folic acid supplements, but many did not. Mandatory food fortification programs were introduced in numerous countries, including the United States, to improve folate nutritional status and have resulted in a major decrease in neural tube defect prevalence. The success story of folate represents the cooperation of embryologists, experimentalists, epidemiologists, public health scientists, and policymakers.

Folic acid and orofacial clefts: a review of the evidence

Orofacial clefts are common and burdensome birth defects with a complex genetic and environmental etiology. The contribution of nutritional factors and supplements to the etiology of orofacial clefts has long been theorized and studied. Multiple studies have evaluated the role of folic acid in the occurrence and recurrence of orofacial clefts, using observational and non-randomized interventional designs. While preventive effects of folic acid on orofacial clefts are commonly reported, the evidence remains generally inconsistent. This paper reviews the findings of the main studies of the effects of folic acid on orofacial clefts, summarizes study limitations, and discusses research needs with a focus on studying the effects of high dosage folic acid on the recurrence of oral clefts using a randomized clinical trial design. The role of folic acid in the prevention of neural tube defects is also briefly summarized and discussed as a reference model for orofacial clefts.

Novel folate binding protein-1 interactions in embryonic orofacial tissue

AIM

To identify proteins with which FolBp1 may interact within lipid rafts in tissue derived from embryonic orofacial tissue.

METHODS

A yeast two-hybrid screen of a cDNA library, derived from orofacial tissue from gestational day 11 to 13 mouse embryos, was conducted.

KEY FINDINGS

Using the full-length FolBp1 protein as bait, two proteins that bind FolBp1 were identified, Bat2d, and a fibronectin type III-containing domain protein. Results were confirmed by glutathione S-transferase pull-down assays.

SIGNIFICANCE

As a component of membrane lipid raft protein complexes, these binding proteins may represent "helper" or chaperone proteins that associate with FolBp1 in order to facilitate the transport of folate across the plasma membrane. The protein-protein interactions detected, while limited in number, may be critical in mediating the role of FolBp1 in folate transport, particularly in the developing embryo.

Nested case-control study of one-carbon metabolites in mid-pregnancy and risks of cleft lip with and without cleft palate

Evidence exists for an association between use of vitamin supplements with folic acid in early pregnancy and reduced risk for offspring with cleft lip with/without cleft palate (CLP). A few observations have been made about nutrients related to one-carbon metabolism other than folate. Our prospective study attempted to extend information on nutrition and CLP by measuring nutrient analytes in mid-pregnancy sera. This study included data from a repository of women's mid-pregnancy serum specimens collected in California from 2003-04. Each woman's specimen was linked with delivery information to determine whether her fetus had CLP or another structural malformation, or was nonmalformed. We identified 89 CLP cases. We randomly selected 409 specimens as controls. Specimens were tested for homocysteine, methylmalonic acid, folate, vitamin B12, pyridoxal phosphate, pyridoxal, pyridoxic acid, riboflavin, choline, betaine, methionine, methionine sulfoxide, cysteine, cystathionine, arginine, and asymmetric and symmetric dimethylarginine. We observed three analytes with odds ratios unlikely to be explained by random variation, i.e., elevated CLP risks were observed for low levels and for high levels of pyridoxal phosphate (vitamin B6), higher levels of choline, and low levels of symmetric dimethylarginine. These data did not show meaningful differences between cases and controls for any other analytes.

118 SNPs of folate-related genes and risks of spina bifida and conotruncal heart defects

Background

Folic acid taken in early pregnancy reduces risks for delivering offspring with several congenital anomalies. The mechanism by which folic acid reduces risk is unknown. Investigations into genetic variation that influences transport and metabolism of folate will help fill this data gap. We focused on 118 SNPs involved in folate transport and metabolism.

Methods

Using data from a California population-based registry, we investigated whether risks of spina bifida or conotruncal heart defects were influenced by 118 single nucleotide polymorphisms (SNPs) associated with the complex folate pathway. This case-control study included 259 infants with spina bifida and a random sample of 359 nonmalformed control infants born during 1983–86 or 1994–95. It also included 214 infants with conotruncal heart defects born during 1983–86. Infant genotyping was performed blinded to case or control status using a designed SNPlex assay. We examined single SNP effects for each of the 118 SNPs, as well as haplotypes, for each of the two outcomes.

Results

Few odds ratios (ORs) revealed sizable departures from 1.0. With respect to spina bifida, we observed ORs with 95% confidence intervals that did not include 1.0 for the following SNPs (heterozygous or homozygous) relative to the reference genotype: BHMT (rs3733890) OR = 1.8 (1.1–3.1), CBS (rs2851391) OR = 2.0 (1.2–3.1); CBS (rs234713) OR = 2.9 (1.3–6.7); MTHFD1 (rs2236224) OR = 1.7 (1.1–2.7); MTHFD1 (hcv11462908) OR = 0.2 (0–0.9); MTHFD2 (rs702465) OR = 0.6 (0.4–0.9); MTHFD2 (rs7571842) OR = 0.6 (0.4–0.9); MTHFR (rs1801133) OR = 2.0 (1.2–3.1); MTRR (rs162036) OR = 3.0 (1.5–5.9); MTRR (rs10380) OR = 3.4 (1.6–7.1); MTRR (rs1801394) OR = 0.7 (0.5–0.9); MTRR (rs9332) OR = 2.7 (1.3–5.3); TYMS (rs2847149) OR = 2.2 (1.4–3.5); TYMS (rs1001761) OR = 2.4 (1.5–3.8); and TYMS (rs502396) OR = 2.1 (1.3–3.3). However, multiple SNPs observed for a given gene showed evidence of linkage disequilibrium indicating that the observed SNPs were not individually contributing to risk. We did not observe any ORs with confidence intervals that did not include 1.0 for any of the studied SNPs with conotruncal heart defects. Haplotype reconstruction showed statistical evidence of nonrandom associations with TYMS, MTHFR, BHMT and MTR for spina bifida.

Conclusion

Our observations do not implicate a particular folate transport or metabolism gene to be strongly associated with risks for spina bifida or conotruncal defects.

Folate-related gene polymorphisms as risk factors for cleft lip and cleft palate

BACKGROUND

Cleft lip with or without cleft palate (CLP) and cleft palate only (CPO) have an inherited component and, many studies suggest, a relationship with folate. Attempts to find folate-related genes associated with clefts have, however, often been inconclusive. This study examined four SNPs related to folate metabolism (MTHFR 677 C-->T, MTHFR 1298 A-->C, MTHFD1 1958 G-->A, and TC II 776 C-->G) in a large Irish population to clarify their relationship with clefts.

METHODS

Cases and their parents were recruited from major surgical centers performing cleft repairs in Ireland and a support organization. Data on risk factors, medical history, and DNA were collected. Controls were pregnant women from the greater Dublin area (n = 1,599).

RESULTS

CLP cases numbered 536 and CPO cases 426 after exclusions. CPO mothers were significantly more likely than controls to be MTHFR 677 TT, OR 1.50 (95% CI: 1.05-2.16; p = .03). Log-linear analysis showed a borderline association (p = .07). Isolated CPO case mothers were significantly more likely than controls to be homozygous for the MTHFD1 1958 G-->A variant, OR 1.50 (95%CI: 1.08-2.09; p = .02). When multiple cases were added, both CPO cases and case mothers were significantly more likely to be AA (p = .02 and p = .007, respectively). The CLP case-control and mother-control analyses also showed significant effects, ORs 1.38 (95% CI: 1.05-1.82; p = .03) and 1.39 (95% CI: 1.04-1.85; p = .03), respectively.

CONCLUSIONS

Associations were found for both CPO and CLP and MTHFD1 1958 G-->A in cases and case mothers. MTHFR 677 C-->T could be a maternal risk factor for clefts but the association was not strong. Because multiple comparisons were made, these findings require additional investigation. Given the known association between MTHFD1 1958 G-->A and NTDs, these findings should be explored in more detail.

High prevalence of orofacial clefts in Shanxi Province in northern China, 2003-2004

Shanxi Province in northern China has been identified as an area with the highest prevalence of neural tube defects in the world; however, few reports exist on the prevalence of orofacial clefts (OFC). We examined the prevalence of OFC and their association with selected characteristics. Data came from a population-based birth defects surveillance system in four counties of Shanxi Province. The system captures information on all live births, stillbirths of at least 20 weeks gestation, and pregnancy terminations at any gestational age after prenatal diagnosis of a birth defect. Out of 25,355 births in 2003-2004, 83 cases with orofacial clefts were identified resulting in a birth prevalence of 3.27 per 1,000. Other major external birth defects were present in 12 (14.5%) OFC cases. Cleft lip with palate (CLP), cleft lip alone (CL) and cleft palate alone (CP) accounted for 62.0%, 29.6% and 8.4% of OFC cases without additional external defects, respectively. The male to female ratio was 1.04 (95%CI: 0.67-1.60) for all OFC, 1.46 (95%CI: 0.80-2.68) for CLP, 1.23 (95%CI: 0.52-2.91) for CL, 0.46 (95%CI: 0.08-2.51) for CP without additional major external defects, and 0.31(95%CI: 0.08-1.13) for OFC with additional external defects. The prevalence of OFC without additional external defects was increased with decreased maternal age (P < 0.05) and increased maternal education (P < 0.05). The birth prevalence of OFC in Shanxi Province of northern China is among the highest worldwide. Further studies are required to define the factors associated with excess risk of clefts.

Folate and Clefts of the Lip and Palate—A U.K.-Based Case-Control Study: Part I: Dietary and Supplemental Folate

Objectives:

We sought to determine the associations between nonsyndromic cleft lip with or without cleft palate (CL−P) and cleft palate only (CP) and maternal intake of dietary folate and supplemental folic acid, in an area where the prevalence at birth of neural tube defects has been high and flour is not fortified with folic acid.

Methods:

Interviews regarding periconceptional dietary intake and supplement use were completed with the mothers of 112 CL−P cases, 78 CP cases, and 248 unaffected infants. The data were analyzed by logistic regression methods.

Results:

There was no overall association between CL−P and CP and either energy-adjusted total folate intake or supplemental folic acid use, irrespective of dosage.

Conclusion:

Overall, higher intakes of total folate do not appear to prevent oral clefts in this population.

Folic acid-containing supplement consumption during pregnancy and risk for oral clefts: a meta-analysis

BACKGROUND

There is equivocal evidence in the published literature that folic acid supplementation during pregnancy may protect against the common congenital anomalies cleft lip with or without cleft palate (CLP) and cleft palate alone (CP). We undertook this meta-analysis to test the hypothesis that nonsyndromic oral cleft birth prevalences are different for those whose mothers took folic acid-containing supplements and for those whose mothers did not.

METHODS

Human studies published in English were identified through MEDLINE, bibliography reviews, and contacting experts in the field. Within strata of prospective and case-control studies, CLP, CP, and all clefts, respectively, were analyzed using either a fixed or random effects model, as appropriate. We assessed for publication bias using Begg and Mazumdar's rank correlation and Egger's regression-based tests.

RESULTS

Five prospective studies were analyzed, yielding combined relative risks of 0.51 (95% CI: 0.32, 0.95) for CLP, 1.19 (95% CI: 0.43, 3.28) for CP, and 0.55 (95% CI: 0.32, 0.95) for all clefts. Twelve case-control studies were assessed, which resulted in combined relative risks of 0.77 (95% CI: 0.65, 0.90) for CLP, 0.80 (95% CI: 0.69, 0.93) for CP, and 0.78 (95% CI: 0.71, 0.85) for all clefts.

CONCLUSIONS

In aggregate, our results support the hypothesis of a protective effect of folic acid-containing supplement intake during pregnancy on the risk for oral clefts, although this conclusion is tempered by the potential for bias and uncontrolled confounding.

Reduction in orofacial clefts following folic acid fortification of the U.S. grain supply

BACKGROUND

Folic acid fortification in the United States became mandatory January 1, 1998, to reduce the occurrence of neural tube defects (NTDs). We evaluated the impact of folic acid fortification on orofacial clefts using United States birth certificate data for 45 states and the District of Columbia.

METHODS

Prevalence ratios (PRs) were calculated comparing orofacial cleft prevalence among births prefortification (1/1990-12/1996) and postfortification (10/1998-12/2002), based on fortification status at conception. The JoinPoint Regression Program and exponentially weighted moving average charts (EWMA) were used to assess the timing of any statistically significant changes in prevalence. Data were stratified by maternal race/ethnicity, age, smoking, and timing of prenatal care.

RESULTS

Orofacial clefts declined following folic acid fortification (PR=0.94; 95% CI: 0.92-0.96). The EWMA chart flagged a significant decrease in the fourth quarter of 1998. The JoinPoint graph had one change in slope, with a significant quarterly percent change (-0.34) between 1996 and 2002. The decline in orofacial clefts occurred in non-Hispanic Whites but not other racial/ethnic groups, nonsmokers but not women who reported smoking during pregnancy, and women who received prenatal care in the first trimester but not women who began receiving care later in pregnancy.

CONCLUSION

Folic acid fortification in the United States was associated with a small decrease in orofacial cleft prevalence, with the timing of the decline consistent with the introduction of fortification. The decline is much smaller than that observed for NTDs, but nonetheless suggests an additional benefit of this public health intervention.

Prenatal multivitamin supplementation and rates of congenital anomalies: a meta-analysis

BACKGROUND

The use of folic acid-fortified multivitamin supplements has long been associated with decreasing the risk of neural tube defects. Several studies have also proposed the effectiveness of these supplements in preventing other birth defects; however, such effects have never been systematically examined.

OBJECTIVE

We conducted a systematic review and meta-analysis to evaluate the protective effect of folic acid-fortified multivitamin supplements on other congenital anomalies.

METHODS

We searched Medline, PubMed, EMBASE, Toxline, Healthstar, and Cochrane databases for studies describing the outcome of pregnancies in women using multivitamin supplements that were published in all languages from January 1966 to July 2005. The references from all collected articles were reviewed for additional articles. Two independent reviewers who were blinded to the source and identity of the articles extracted data based on predetermined inclusion and exclusion criteria. Using a random effects model, rates of congenital anomalies in babies born to women who were taking multivitamin supplements were compared with rates in the offspring of controls who were not.

RESULTS

From the initial search, 92 studies were identified; 41 of these met the inclusion criteria. Use of multivitamin supplements provided consistent protection against neural tube defects (random effects odds ratio[OR] 0.67, 95% confidence intervals [95% CI] 0.58-0.77 in case control studies; OR 0.52, 95% CI 0.39-0.69 in cohort and randomized controlled studies), cardiovascular defects (OR 0.78, 95% CI 0.67-0.92 in case control studies; OR 0.61, 95% CI 0.40-0.92 in cohort and randomized controlled studies), and limb defects (OR 0.48, 95% CI 0.30-0.76 in case control studies; OR 0.57, 95% CI 0.38-0.85 in cohort and randomized controlled studies). For cleft palate, case control studies showed OR 0.76 (95% CI 0.62-0.93), and cohort and randomized controlled studies showed OR 0.42 (95% CI 0.06-2.84); for oral cleft with or without cleft palate, case control studies showed OR 0.63 (95% CI 0.54-0.73), and cohort and randomized controlled studies showed OR 0.58 (95% CI 0.28-1.19); for urinary tract anomalies, case control studies showed OR 0.48 (95% CI 0.30-0.76), and cohort and randomized controlled studies showed OR 0.68 (95% CI 0.35-1.31); and for congenital hydrocephalus case control studies showed OR 0.37 (95% CI 0.24-0.56), and cohort and randomized controlled studies showed OR 1.54 (95% CI 0.53-4.50). No effects were shown in preventing Down syndrome, pyloric stenosis, undescended testis, or hypospadias.

CONCLUSION

Maternal consumption of folic acid-containing prenatal multivitamins is associated with decreased risk for several congenital anomalies, not only neural tube defects. These data have major public health implications, because until now fortification of only folic acid has been encouraged. This approach should be reconsidered.

Maternal nutrient intakes and risk of orofacial clefts

BACKGROUND

Information about nutritional factors as potential risks of orofacial clefts is limited.

METHODS

In this population-based case-control study, we investigated whether periconceptional intakes of supplemental folic acid, dietary folate, and several other nutrients were associated with orofacial clefts. We included data on deliveries from 1997 through 2000 in the National Birth Defects Prevention Study. Orofacial cleft cases were infants or fetuses born with cleft palate (CP) or with cleft lip with or without cleft palate (CLP). Infants without malformations were eligible as controls. Interview participation was 71% among case mothers and 68% among control mothers. Interviews were completed for 704 CLP cases, 404 CP cases, and 2594 controls.

RESULTS

The odds ratio (OR) for CLP associated with use of vitamin supplements containing folic acid was 0.88 (95% confidence interval = 0.73-1.07) and for CP was 1.09 (0.84-1.40). Adjusting for maternal race/ethnicity, age, and education produced an OR of 1.01 (0.82-1.24) for CLP and 1.02 (0.77-1.34) for CP. We found some evidence for decreased CLP risks (>or=30% reduction in risk) with increasing intakes of total protein, choline, and methionine. Decreased CP risk was associated with increased intake of cysteine. Intakes of only 2 micronutrients, iron and riboflavin, were found to reduce CLP risk when adjusted for other nutrients.

CONCLUSION

Our observations contribute to the limited body of evidence suggesting a woman's periconceptional diet may influence clefting risks in her offspring. Our finding of no reduction in clefting risk with periconceptional use of supplements containing folic acid is inconsistent with many previous observations but not all.

Prevalence of nonsyndromic oral clefts in Texas: 1995-1999

Nonsyndromic cleft lip with/without cleft palate (NSCLP) and nonsyndromic cleft palate only (NSCPO) are common complex birth defects affecting 4,000 newborns annually. We undertook a descriptive study of oral clefts in Texas, focusing on the effect of folic acid fortification and Hispanic ethnicity on the prevalence of oral clefts as these factors have not previously been described. Data on 896 infants with NSCLP and NSCPO born between 1995 and 1999 in Texas were compared to all births in Texas during the same period. Prevalence odds ratios (POR) were calculated for maternal ethnicity, race, age, parity, public health region of residence, highest level of education, and infant gender. The effect of folic acid fortification on oral clefts was also examined. Compared with whites, adjusted POR were 0.97 (95% CI = 0.77-1.23) and 0.90 (95% CI 0.72-1.14) for NSCLP and 0.46 (95% CI = 0.30-0.72) and 0.62 (95% CI = 0.42-0.90) for NSCPO in foreign-born and US-born Hispanics, respectively. After fortification was implemented, the rate of NSCLP did not decrease. However, there was a 13% decrease in the prevalence of NSCPO (adjusted POR = 0.87, 95% CI = 0.68-1.15). Compared to whites, the rates in US-born and foreign-born Hispanic women were similar for NSCLP and much lower for NSCPO. The small reduction of 13% in NSCPO after folic acid fortification is imprecise and should be interpreted cautiously. Overall, it appears that folic acid fortification has had very little or no effect on the prevalence of oral clefts in infants born in Texas.

Cystathionine beta-synthase c.844ins68 gene variant and non-syndromic cleft lip and palate

Non-syndromic cleft lip with or without cleft palate (CL/P) is a common birth defect with substantial clinical and social impact and whose causes include both genetic and environmental factors. Folate and homocysteine (Hcy) metabolism have been indicated to play a role in the etiology of CL/P, and polymorphisms in folate and Hcy genes may act as susceptibility factors. We investigated a common polymorphism in the cystathionine beta-synthase (CBS) gene (c.844ins68) in 134 Italian CL/P cases and their parents using the transmission disequilibrium test (TDT). Although no overall linkage disequilibrium was observed, considering the parent-of-origin transmission of the CBS 68 bp insertion a significant (P = 0.002) transmission distortion was detected. When children receive the c.844ins68 allele from the mother compared to the father, they show a 18.7-fold increase in risk for CL/P. This evidence suggests CBS as a candidate gene for CL/P and supports a role of maternal-embryo interactions in the etiology of CL/P.

Folic Acid Food Fortification in Canada

By January 1998, most Canadian cereal grains (e.g., white flour) were being fortified with folic acid, with a large percentage being fortified by mid-1997. This was in compliance with both American and Canadian mandatory fortification deadlines of January and November 1998, respectively. It was estimated that between 0.1 to 0.2 mg of additional synthetic folic acid per day would be provided through this initiative, the goal of which was to lower the rate of neural tube defects (NTD). The current report outlines some of the changes to the health status of Canadians in relation to its folic acid food fortification initiative.

Preconception care: a systematic review

OBJECTIVES

To perform a systematic review of published research trials of preconception care services to determine what evidence for effectiveness of care at improving the course of pregnancy or its outcomes has accumulated since the last major review in 1990.

METHODS

The review was conducted adapting the systematic methods developed by the Cochrane Collaboration to collect evidence from published clinical research literature with as little bias as possible. The review included literature published after January 1990, and posted on MEDLINE by July 1999.

RESULTS

Although more than 40 preconception risk conditions were searched and 470 articles were abstracted, only four problem areas and 19 research trials met the review criteria. New evidence of effectiveness was found for screening women who are seeking family planning for risk conditions; having sexually active women of reproductive age take dietary folate supplements; and providing women affected by certain metabolic conditions (diabetes and hyperphenylalanemia) with nutrition services.

CONCLUSIONS

To help improve pregnancy outcomes MCH professionals need to promote the concept of readiness for pregnancy and help see that women are as healthy and appropriately nourished as possible before they become pregnant.