Serum exosomal coronin 1A and dynamin 2 as neural tube defect biomarkers.

No highly specific and sensitive biomarkers have been identified for early diagnosis of neural tube defects (NTDs). In this study, we used proteomics to identify novel proteins specific for NTDs. Our findings revealed three proteins showing differential expression during fetal development. In a rat model of NTDs, we used western blotting to quantify proteins in maternal serum exosomes on gestational days E18, E16, E14, and E12, in serum on E18 and E12, in neural tubes on E18 and E12, and in fetal neural exosomes on E18. The expression of coronin 1A and dynamin 2 was exosome-specific and associated with spina bifida aperta embryogenesis. Furthermore, coronin 1A and dynamin 2 were significantly downregulated in maternal serum exosomes (E12-E18), neural tubes, and fetal neural exosomes. Although downregulation was also observed in serum, the difference was not significant. Differentially expressed proteins were further analyzed in the serum exosomes of pregnant women during gestational weeks 12-40 using enzyme-linked immunosorbent assays. The findings revealed that coronin 1A and dynamin 2 showed potential diagnostic efficacy during gestational weeks 12-40, particularly during early gestation (12-18 weeks). Therefore, these two targets are used as candidate NTD screening and diagnostic biomarkers during early gestation. KEY MESSAGES: We used proteomics to identify novel proteins specific for NTDs. CORO1A and DNM2 showed exosome-specific expression and were associated with SBA. CORO1A and DNM2 were downregulated in maternal serum exosomes and FNEs. CORO1A and DNM2 showed good diagnostic efficacy for NTDs during early gestation. These two targets may have applications as NTD screening and diagnostic biomarkers.

Genetic Polymorphisms in DNA Repair Gene APE1/Ref-1 and the Risk of Neural Tube Defects in a High-Risk Area of China.

Apurinic/apyrimidinic endonuclease 1/redox-factor 1 (APE1/Ref-1) gene encodes a multifunctional protein involved in the DNA base excision repair (BER) pathway, which initiates repair of apurinic/apyrimidinic (AP) sites in DNA by catalyzing hydrolytic incision of the phosphodiester backbone. APE1/Ref-1 polymorphisms are related to the occurrence of neural tube defects (NTDs), but the association between APE1/Ref-1 polymorphisms and NTDs is not reported in Chinese Han population. The aim of the present study was to evaluate the association of APE1/Ref-1 polymorphism and the risk of NTD occurrence for Han population in a high-risk area of China. APE1/Ref-1 genotypes were determined by iPLEX Gold SNP genotyping. AP sites and folate level of brain tissues were measured. The results showed that three polymorphisms (rs3136817, rs77794916, and rs1760944) of APE1/Ref-1 were statistically associated with NTD subtypes. Allele C of rs3136817, allele T of rs77794916, and allele G of rs1760944 were associated with an increased risk for encephalocele (OR = 2.52, 95% CI [1.25-5.07], P < 0.01; OR = 1.80, 95% CI [1.04-3.12], P = 0.04; and OR = 1.96, 95% CI [1.12-3.45], P = 0.02), compared with those harboring the alleles T, C, and T, respectively. The folate level in NTDs was lower than that in controls. DNA AP sites in the encephalocele were significantly higher than the control (P < 0.01). The three polymorphisms of APE1/Ref-1 were significantly related to NTD occurrence, which indicated that APE1/Ref-1 might be a potential genetic risk factor for encephalocele in a high-risk area of NTDs in China.

Complement factors and alpha-fetoprotein as biomarkers for noninvasive prenatal diagnosis of neural tube defects.

Neural tube defects (NTDs) are serious congenital malformations. In this study, we aimed to identify more specific and sensitive maternal serum biomarkers for noninvasive NTD screenings. We collected serum from 37 pregnant women carrying fetuses with NTDs and 38 pregnant women carrying normal fetuses. Isobaric tags for relative and absolute quantitation were conducted for differential proteomic analysis, and an enzyme-linked immunosorbent assay was used to validate the results. We then used a support vector machine (SVM) classifier to establish a disease prediction model for NTD diagnosis. We identified 113 differentially expressed proteins; of these, 23 were either up- or downregulated 1.5-fold or more, including five complement proteins (C1QA, C1S, C1R, C9, and C3); C3 and C9 were downregulated significantly in NTD groups. The accuracy rate of the SVM model of the complement factors (including C1QA, C1S, and C3) was 62.5%, with 60% sensitivity and 67% specificity, while the accuracy rate of the SVM model of alpha-fetoprotein (AFP, an established biomarker for NTDs) was 62.5%, with 75% sensitivity and 50% specificity. Combination of the complement factor and AFP data resulted in the SVM model accuracy of 75%, and receiver operating characteristic curve analysis showed 75% sensitivity and 75% specificity. These data suggest that a disease prediction model based on combined complement factor and AFP data could serve as a more accurate method of noninvasive prenatal NTD diagnosis.

NEURAL TUBE DEFECTS AND MICRONUTRIENTS DEFICIENCY PREVALENCE IN GEORGIA.

Until 2015, systematic statistical data on micronutrient deficiency was not available in Georgia, to provide developing national strategy. In the same year, the National Centre for Disease Control and Public Health of Georgia (NCDC) in collaboration with the USA CDC launched the project "Strengthening surveillance of micronutrient deficiency in Georgia". In 2015 we did choose sentinel surveillance approach. For setting nutrition surveillance system 8 sentinel sites (2 sites in each region/children and pregnant health facilities) in four regions of Georgia (Tbilisi, Kakheti, Achara, and Samegrelo) were selected, using the criteria of geographical, social, ethnical, urban/rural, and religion. Also, existing information about malnutrition and dietary habits from the above mentioned regions. The project protocols was approved by the Institutional review board (IRB) at the NCDC and by the Research Review Committee and Ethical review committee of the US CDC. As a result of surveillance system functioning (2016-2019) we reviled that, about 36% out of 1021 studied children U2 (12-23 months) were anemic, 74% of them were identified as iron deficient. Hemoglobin was tested among 963 pregnant women and about 21% of them were found anemic, 57% were iron deficient, and 28% tested positive for folate deficiency. Neural tube defects (NTDs) prevalence per 1000 live births registered in sentinel sites was high 3.7. Our results show that anemia and iron deficiency are prevalent among both pregnant women and children of the specified age group in Georgia. Additionally, folate deficiency was quite common during the1st trimester of pregnancy. Our findings will inform public health policy decision makers to take relevant decisions on required interventions, such as health education, distribution of relevant supplements, and food fortification.

Expression of Sigma-Class Glutathione-S-Transferase in Fetal and Pediatric Filum Terminale Samples: A Comparative Study.

Background and objectives: The pathophysiology of tethered cord syndrome (TCS) in children is not well elucidated. An inelastic filum terminale (FT) is the main factor underlying the stretching of the spinal cord in TCS. Our study aimed to investigate the expression of glutathione-S-transferase (GST) in children and fetal FT samples in order to understand the relationship between this enzyme expression and the development of TCS. Materials and Methods: FT samples were obtained from ten children with TCS (Group 1) and histological and immunohistochemical examinations were performed. For comparison, FT samples from fifteen normal human fetuses (Group 2) were also analyzed using the same techniques. Statistical comparison was made using a Chi-square test. Results: Positive GST-sigma expression was detected in eight (80%) of 10 samples in Group 1. The positive GST-sigma expression was less frequent in nine (60%) of 15 samples from Group 2. No statistically significant difference was detected between the two groups (p = 0.197). Conclusions: Decreased FT elasticity in TCS may be associated with increased GST expression in FT. More prospective studies are needed to clarify the mechanism of the GST-TCS relationship in children.

Quantitation of 5-methyltetraydrofolic acid in plasma for determination of folate status and clinical studies by stable isotope dilution assays.

Folates play a key role in the prevention of neural tube defects in newborns. Thus, it is important to reliably determine the bioavailability of folates from various foods. Accurate analytical methods are essential for quantifying blood-folates, especially in human studies. Here, we present the development and validation of a sensitive method using stable isotope dilution liquid chromatography coupled with mass spectrometry for determining various folates in plasma. Moreover, this study reports the applicability of the developed method to a human pilot study using strawberries as a test food. Validation of the assay revealed the precision, sensitivity, and accuracy of the method in determining the predominant 5-methyltetrahydrofolate in plasma. This method was also applicable for the screening of individual folate status using finger prick blood and for monitoring the post-absorptive plasma-concentration curve. Moreover, the human study revealed a high recovery of strawberry folates with a calculated relative bioavailability of 96.2%. Thus, the developed method enables prospective bioavailability studies. This work also confirmed, via human studies, that strawberries are a rich and natural source of folates that are available for human metabolism.

Maternal second trimester blood levels of selected heavy metals in pregnancies complicated with neural tube defects.

PURPOSE: Neural tube defects (NTDs) are the most common malformations of the central nervous system (CNS). There is continuing research for the identification of risk factors and interventions for prevention of NTDs. The aim of this study was to investigate the maternal second trimester blood levels of selected heavy metals namely, arsenic (As), cadmium (Cd), mercury (Hg), manganese (Mn), nickel (Ni), and lead (Pb) and their possible relation with the occurrence of NTDs. METHODS: Twenty-one healthy second trimester pregnant women with fetuses affected with NTD (cases) were matched with 21 healthy pregnant women with unaffected fetuses (controls) with respect to age, body mass index (BMI), and gestational age. Maternal blood levels of heavy metals were measured after an overnight fasting period. RESULTS: No significant differences were observed in terms of maternal blood levels of As, Cd, Hg, and Ni between NTD-affected and unaffected pregnancies. The blood Pb and Mn levels were found to be higher in pregnant women with a fetus affected with NTD when compared with pregnant women with unaffected fetuses (for Pb, in cases 12.3 ± 5.5 µg/L, in controls 7.8 ± 2.4 µg/L; for Mn in cases 3.6 ± 1.4 µg/L, in controls 2.4 ± 1.0 µg/L, p < .05). CONCLUSIONS: High maternal second trimester blood levels of Pb and Mn during pregnancy are associated with NTDs in the newborn.

Homocysteine and vitamin B12: Other causes of neural tube defects in Eastern Uttar Pradesh and Western Bihar population.

BACKGROUND: Neural tube defects (NTDs) are congenital malformations with an incidence of 1-10/1000 live births. Homocysteine and vitamin B12 metabolism have been shown to be associated with NTDs. AIM: To investigate the status of maternal and neonate's folic acid, homocysteine, and vitamin B12 levels and their association with the risk of development of NTDs in the population of Eastern Uttar Pradeshand Western Bihar, India. MATERIALS AND METHODS: This study is a cross-sectional, retrospective study where 96 mothers who either had a first NTD child or had a history of NTD child in the family and 126 neonates with spina bifida were recruited during the period 2012-2015. Eighty-four control mothers whose previous and current pregnancies were normal, and 87 control neonates who had no defects and were within the same age range as the NTD affected neonates, recruited from the department of pediatric surgery, were enrolled in the study. Plasma concentrations of folic acid, vitamin B12, and homocysteine were compared between cases and controls. RESULTS: The folic acid level in the mothers and neonates was within the normal limit. A significant increase in the level of homocysteine in mothers with affected pregnancy and in neonate cases in comparison to control mothers was obseved. Further, a significant decrease in the level of vitamin B12 in mothers with NTD neonates and in the affected neonates was noted. A negative correlation was found between homocysteine and vitamin B12 levels in case and control mothers. CONCLUSION: A correlation of an increase in serum homocysteine with a decrease in vitamin B12 was seen in mothers of neonates with NTD. A similar observation as made in the neonates with NTDs. It may be suggested that maternal decrease in vitamin B12, in mothers who have normal folic acid may be associated with NTD in their children.

Folic acid and primary prevention of neural tube defects: A review.

With 4 mg folic acid daily, it may take 20 weeks to reach red-blood-cell folate levels between 1050 and 1340 nmol/L, optimal for reduction of the neural tube defect risk. Therefore, folic acid supplementation should be started 5-6 months before conception. The residual risk with optimal red-blood-cell folate levels is reportedly 4.5 per 10,000 total births. The residual risk in pooled data from countries with mandatory folic acid fortification is 7.5 per 10,000 pregnancies, regardless of pre-fortification rates. European monitoring of folate intake with questionnaires should be replaced by periodic measurements of red-blood-cell folate. The risk of folate intake >1 mg/day does not outweigh the benefits of folic acid fortification, provided un-metabolized folic acid, RBC folate and vitamin B12 are monitored periodically. A European monitoring system, based on U.S. National Health and Nutrition Examination Surveys, should reside with the European Centre for Disease Prevention and Control.

LRP2 gene variants and their haplotypes strongly influence the risk of developing neural tube defects in the fetus: a family-triad study from South India.

Neural tube defects (NTDs) are the leading cause of infant deaths worldwide. Lipoprotein related receptor 2 (LRP2) has been shown to play a crucial role in neural tube development in mouse models. However, the role of LRP2 gene in the development of human NTDs is not yet known. In view of this, family-based triad approach has been followed considering 924 subjects comprising 124 NTD case-parent trios and 184 control-parent trios diagnosed at Institute of Genetics and Hospital for Genetic Diseases, Hyderabad. Blood and tissue samples were genotyped for rs3755166 (-G759A) and rs2544390 (C835T) variants of LRP2 gene for their association with NTDs. Assessment of maternal-paternal genotype incompatibility risk for NTD revealed 3.77-folds risk with a combination of maternal GA and paternal GG genotypes (GAxGG = GA,p < 0.001), while CT genotypes of both the parents showed 4.19-folds risk for NTDs (CTxCT = CT,p = 0.009). Haplotype analysis revealed significant risk of maternal A-T (OR = 4.48,p < 0.001) and paternal G-T haplotypes (OR = 5.22,p < 0.001) for NTD development. Further, linkage analysis for parent-of-origin effects (POE) also revealed significant transmission of maternal 'A' allele (OR = 2.33,p = 0.028) and paternal 'T' allele (OR = 6.00,p = 0.016) to NTDs. Analysis of serum folate and active-B12 levels revealed significant association with LRP2 gene variants in the causation of NTDs. In conclusion, the present family-based triad study provides the first report on association of LRP2 gene variants with human NTDs.

Improving maternal folate status to prevent infant neural tube defects: working group conclusions and a framework for action.

As infectious disease control programs achieve increasing success, further reductions in child mortality in low- and middle-income countries (LMICs) will require focused prevention strategies for birth defects and other noninfectious diseases. Neural tube defects (NTDs) can cause early death or lifelong disability. Preventing NTDs provides a feasible, significant opportunity to decrease the toll of birth defects and contribute to further reducing child mortality globally. The Micronutrient Forum convened a technical consultation on Folate Status in Women and Neural Tube Defects Prevention to develop a roadmap to inform and prioritize investments in NTD prevention in LMICs; help guide implementation efforts in terms of the feasibility of interventions and the potential for acceleration; and identify research and knowledge gaps. Here, we describe the impetus for and approach to the consultation and present the conclusions and a framework for developing a roadmap for action to accelerate NTD prevention in LMICs. The framework (1) provides options for action on folate status assessment; (2) outlines a way forward to develop and implement a time-bound global action plan for NTD prevention; and (3) identifies common impediments to NTD prevention, broad strategies to overcome or minimize these impediments, and basic building blocks necessary to accelerate action.

Digenic variants of planar cell polarity genes in human neural tube defect patients.

Neural tube defects (NTDs) are considered to be a complex genetic disorder, although the identity of the genetic factors remains largely unknown. Mouse model studies suggest a multifactorial oligogenic pattern of inheritance for NTDs, yet evidence from published human studies is surprisingly absent. In the present study, targeted next-generation sequencing was performed to screen for DNA variants in the entire coding regions and intron-exon boundaries of targeted genes using DNA samples from 510 NTD cases. These candidate genes were PCP genes, including VANGL1, VANGL2, CELSR1, SCRIB, DVL2, DVL3 and PTK7. Candidate variants were validated using Sanger sequencing. A total of 397 single nucleotide variants(SNVs) were identified with a mean depth of approximately 570×. Of these identified SNVs, 74 were predicted to affect protein function and had a minor allele frequency of <0.01 or unknown. Among these 74 missense SNVs, 10 were identified from six NTD cases that carried two mutated genes. Of the six NTD cases, three spina bifida cases and one anencephaly case carried digenic variants in the CELSR1 and SCRIB gene; one anencephaly case carried variants in the CELSR1 and DVL3 gene; and one spina bifida case carried variants in the PTK7 and SCRIB genes. Three cases that parental samples were available were confirmed to be compound heterozygous. None of the digenic variants were found in the 1000 genome database. The findings imply that genetic variation might interact in a digenic fashion to generate the visible NTD phenotypes and emphasize the importance of these genetic interactions in the development of NTDs in humans.

Should vitamin B12 status be considered in assessing risk of neural tube defects?

There is a strong biological premise for including vitamin B12 with folic acid in strategies to prevent neural tube defects (NTDs), due to the closely interlinked metabolism of these two vitamins. For example, reduction of B12 deficiency among women of reproductive age could enhance the capacity of folic acid to prevent NTDs by optimizing the cellular uptake and utilization of natural folate cofactors. Vitamin B12 might also have an independent role in NTD prevention, such that adding it in fortification programs might be more effective than fortifying with folic acid alone. Globally, there is ample evidence of widespread vitamin B12 deficiency in low- and middle-income countries, but there is also considerable divergence of vitamin B12 status across regions, likely due to genetic as well as nutritional factors. Here, I consider the evidence that low vitamin B12 status may be an independent factor associated with risk of NTDs, and whether a fortification strategy to improve B12 status would help reduce the prevalence of NTDs. I seek to identify knowledge gaps in this respect and specify research goals that would address these gaps.

Comparison of serum folate, 25-OH vitamin D, and calcium levels between pregnants with and without fetal anomaly of neural tube origin.

AIM: The aim of this study was to compare serum folate, vitamin B12, 25-OH vitamin D, and calcium levels between pregnants with and without fetal anomaly of neural tube origin. METHODS: One hundred seventy-eight pregnants were recruited for this study. Pregnants with and without sonographically detected fetal anomaly of neural tube origin were compared in terms of serum folate, vitamin B12, 25-OH vitamin D, and calcium levels. RESULTS: There were significant differences between groups with regard to age, serum 25 OH vitamin D, 1,25 OH vitamin D, folate, calcium, and B 12 levels. Multivariate regression analyses revealed significant associations between the serum 25 OH vitamin D level, age, and the neural tube defect (NTD). CONCLUSIONS: Vitamin D and the age of pregnants were significantly associated with the NTDs.

Low maternal folate concentrations and maternal MTHFR C677T polymorphism are associated with an increased risk for neural tube defects in offspring: a case-control study among Pakistani case and control mothers.

BACKGROUND AND OBJECTIVES: There is considerable evidence that periconceptional maternal folate deficiency and coding variants in maternal genes coding for critical enzymes in the folate pathway are associated with neural tube defects (NTDs) in offspring. In a case-control study we investigated C677T polymorphism in the 5,10- methylenetetrahydrofolate reductase (MTHFR) gene in case and control mothers of Pakistani origin, and compared these with the respective maternal folate concentrations measured at the time of delivery. METHODS AND STUDY DESIGN: A case-control study was conducted among 109 case and 100 control mothers identified through the Holy Family Hospital Rawalpindi, Quaid-i-Azam University, Islamabad, Pakistan. Red blood cell (RBC) and serum folate concentrations and MTHFRC677T polymorphism were compared between case and control mothers. RESULTS: Mean RBC folate and serum folate concentrations were significantly lower in cases compared with control mothers (p<0.0001). Maternal MTHFR 677CT and 677TT genotypes were more common among cases compared with control mothers (CC vs TT p<0.0393 and CC/CT vs TT p<0.021). T-allele frequency was higher in cases compared with control mothers (C vs T p<0.017). Case mothers with 677CT or 677TT genotypes had significantly lower serum (p<0.0001) and RBC folate concentrations (p<0.0001) compared with control mothers. CONCLUSIONS: The present study provides further evidence that maternal folate deficiency and MTHFRC677T polymorphism might be associated with an increased risk for NTDs in offspring. Our results are limited by the fact that maternal folate concentrations were not obtained during the periconceptional period, but at delivery. Further analyses, including maternal folate levels during the periconceptional period, are warranted.

Folate status in women of reproductive age as basis of neural tube defect risk assessment.

Reliable folate status data for women of reproductive age (WRA) to assess global risk for neural tube defects (NTDs) are needed. We focus on a recent recommendation by the World Health Organization that a specific "optimal" red blood cell (RBC) folate concentration be used as the sole indicator of NTD risk within a population and discuss how to best apply this guidance to reach the goal of assessing NTD risk globally. We also emphasize the importance of using the microbiologic assay (MBA) as the most reliable assay for obtaining comparable results for RBC folate concentration across time and countries, the need for harmonization of the MBA through use of consistent key reagents and procedures within laboratories, and the requirement to apply assay-matched cutoffs for folate deficiency and insufficiency. To estimate NTD risk globally, the ideal scenario would be to have country-specific population-based surveys of RBC folate in WRA determined utilizing a harmonized MBA, as was done in recent studies in Guatemala and Belize. We conclude with guidance on next steps to best navigate the road map toward the goal of generating reliable folate status data on which to assess NTD risk in WRA in low- and middle-income countries.

CSF-Based Analysis for Identification of Potential Serum Biomarkers of Neural Tube Defects.

The protein composition of cerebrospinal fluid (CSF) in neural tube defects (NTDs) remains unknown. We investigated the protein composition of CSF from 9 infants with NTDs using isobaric tags for relative and absolute quantitation (iTRAQ). We identified 568 proteins in the CSF of infants with spina bifida, which is the most common type of NTD. Among these, 18 proteins were associated with neural tube closure in the CSF during human embryonic neurulation and 5 were involved in NTDs. Based on these results, an animal model was further utilized to investigate early serum biomarkers for NTDs. We found that the myristoylated alanine-rich C-kinase substrate, Kunitz-type protease inhibitor 2, and apolipoprotein B-100 protein levels were decreased in both embryos and the sera of pregnant Sprague-Dawley rats carrying embryos with NTDs. CSF proteins may be useful in the discovery of potential serum biomarkers for NTDs.

Plasma folate levels and associated factors in women planning to become pregnant in a population with high prevalence of neural tube defects.

BACKGROUND: Optimal blood folate levels of women before pregnancy are critical to the prevention of neural tube defects (NTDs). However, few studies have focused on blood folate levels of women planning to become pregnant. The aims of this study were to assess plasma folate levels in women who planned to become pregnant in a population with high prevalence of NTDs, to identify factors associated with plasma folate levels, and to evaluate the risk of NTDs at the population level. METHODS: A total of 2065 women were enrolled at the time of premarital health check-up in two rural counties in northern China from November 2009 to December 2012. Fasting venous blood samples were collected and plasma folate concentrations were measured by microbiological method. RESULTS: The overall median of plasma folate was 10.5 nmol/L. 50% of the women had a plasma folate level below 10.5 nmol/L, a cutoff for megaloblastic anemia, and 88% below 18 nmol/L, a proposed optimal plasma folate level for the prevention of NTDs. Folic acid supplementation was the only factor to be associated with plasma folate concentrations, but only 1.9% of the women reported having taken folic acid supplements. A population risk of 29.3 NTD cases per 10,000 births was predicted. CONCLUSION: Women who planned to become pregnant had very low plasma folate in the population. Folic acid supplementation was the only factor to be associated with a high plasma folate concentration. High NTD risk would remain if women would get pregnant without having taken folic acid supplements. Birth Defects Research 109:1039-1047, 2017. © 2017 Wiley Periodicals, Inc.

Maternal serum thiol/disulfide homeostasis in pregnancies complicated by neural tube defects: report of a preliminary study.

OBJECTIVE: To determine and evaluate the maternal serum thiol/disulfide homeostasis in pregnancies complicated by neural tube defects (NTD) via a novel method. METHODS: Seventy-three pregnant women with NTD (study group) and seventy-one healthy control pregnant women (control group) were included in the study. A new and fully automated method was used to measure plasma native thiol, total thiol and disulfide levels, based on the reduction of dynamic disulfide bonds to functional thiol groups by sodium borohydrate. RESULTS: The study and control groups were gestational age-matched. There were no statistical differences in demographic variables regarding age, gravidity, parity and body mass index. The serum native thiol levels (-SH) were 360.5 ± 50.3 and 353.3 ± 31.0 µmol/l in study and control groups, respectively, which was not statistically different (p = 0.308). The native thiol/total thiol, disulfide/native thiol and disulfide/total thiol ratios were not statistically significantly different (p > 0.05). CONCLUSION: Our preliminary results show that maternal serum thiol/disulfide homeostatis does not change in pregnancies complicated by NTD. Larger further studies are required to evaluate the relation of oxidative stress and development of NTD.

Elevated homocysteine levels in mothers with neural tube defects: a systematic review and meta-analysis.

PURPOSE: To find the real relationship between maternal total homocysteine (tHcy) level and risk of neural tube defects (NTDs). MATERIALS AND METHODS: A systematic review and meta-analysis were conducted. The literature search was conducted with the use of PubMed and EMBASE databases and weighted mean difference (WMD) with 95% confidence interval (CI) was applied to measure the difference in tHcy level between case and control group. Seventeen articles involving 3237 subjects were included according to the inclusion criteria. RESULTS: Pooled result showed that mothers with NTDs offspring demonstrated significantly a higher mean log plasma tHcy level than mothers with normal offspring (log WMD: 0.06; 95%CI: 0.02-0.09, p = 0.001), corresponding to an increase of 6% (2-9%) in the geometric mean. Subgroup analyses also displayed this difference in subjects who were detected during pregnancy or without folate supplementation before sampling. However, in the mandatory folate fortification countries, we did not find this association. CONCLUSIONS: A slightly higher tHcy level in mothers with NTDs was indicated, but potential confounders could not be ruled out completely. Further larger or cohort studies are needed to confirm this association.