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Molloy AM. Should vitamin B 12 status be considered in assessing risk of neural tube defects? Ann N Y Acad Sci 2018; 1414:109-125. [PMID: 29377209 PMCID: PMC5887889 DOI: 10.1111/nyas.13574] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/07/2017] [Accepted: 11/11/2017] [Indexed: 02/06/2023]
Abstract
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.
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Affiliation(s)
- Anne M Molloy
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Trinity Biomedical Sciences Institute, Dublin, Ireland
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George Priya Doss C, Rajith B, Magesh R, Ashish Kumar A. Influence of the SNPs on the structural stability of CBS protein: Insight from molecular dynamics simulations. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s11515-014-1320-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Tzeng JY, Lu W, Hsu FC. GENE-LEVEL PHARMACOGENETIC ANALYSIS ON SURVIVAL OUTCOMES USING GENE-TRAIT SIMILARITY REGRESSION. Ann Appl Stat 2014; 8:1232-1255. [PMID: 25018788 DOI: 10.1214/14-aoas735] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Gene/pathway-based methods are drawing significant attention due to their usefulness in detecting rare and common variants that affect disease susceptibility. The biological mechanism of drug responses indicates that a gene-based analysis has even greater potential in pharmacogenetics. Motivated by a study from the Vitamin Intervention for Stroke Prevention (VISP) trial, we develop a gene-trait similarity regression for survival analysis to assess the effect of a gene or pathway on time-to-event outcomes. The similarity regression has a general framework that covers a range of survival models, such as the proportional hazards model and the proportional odds model. The inference procedure developed under the proportional hazards model is robust against model misspecification. We derive the equivalence between the similarity survival regression and a random effects model, which further unifies the current variance-component based methods. We demonstrate the effectiveness of the proposed method through simulation studies. In addition, we apply the method to the VISP trial data to identify the genes that exhibit an association with the risk of a recurrent stroke. TCN2 gene was found to be associated with the recurrent stroke risk in the low-dose arm. This gene may impact recurrent stroke risk in response to cofactor therapy.
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Affiliation(s)
- Jung-Ying Tzeng
- North Carolina State University ; National Cheng-Kung University
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Hsu FC, Sides EG, Mychaleckyj JC, Worrall BB, Elias GA, Liu Y, Chen WM, Coull BM, Toole JF, Rich SS, Furie KL, Sale MM. Transcobalamin 2 variant associated with poststroke homocysteine modifies recurrent stroke risk. Neurology 2011; 77:1543-50. [PMID: 21975197 DOI: 10.1212/wnl.0b013e318233b1f9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVES The Vitamin Intervention for Stroke Prevention trial found an association between baseline poststroke homocysteine (Hcy) and recurrent stroke. We investigated genes for enzymes and cofactors in the Hcy metabolic pathway for association with Hcy and determined whether associated single nucleotide polymorphisms (SNPs) influenced recurrent stroke risk. METHODS Eighty-six SNPs in 9 candidate genes (BHMT1, BHMT2, CBS, CTH, MTHFR, MTR, MTRR, TCN1, and TCN2) were genotyped in 2,206 subjects (83% European American). Associations with Hcy measures were assessed using linear regression models assuming an additive genetic model, adjusting for age, sex, and race and additionally for baseline Hcy when postmethionine load change was assessed. Associations with recurrent stroke were evaluated using survival analyses. RESULTS Five SNPs in the transcobalamin 2 (TCN2) gene were associated with baseline Hcy (false discovery rate [FDR]-adjusted p = 0.049). TCN2 SNP rs731991 was associated with recurrent stroke risk in the low-dose arm of the trial under a recessive model (log-rank test p = 0.009, hazard ratio 0.34). Associations with change in postmethionine load Hcy levels were found with 5 SNPs in the cystathionine β-synthase (CBS) gene (FDR-adjusted p < 0.031). CONCLUSIONS TCN2 variants contribute to poststroke Hcy levels, whereas variants in the CBS gene influence Hcy metabolism. Variation in the TCN2 gene also affects recurrent stroke risk in response to cofactor therapy.
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Affiliation(s)
- F-C Hsu
- Department of Biostatistical Sciences, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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Tilley MM, Northrup H, Au KS. Genetic studies of the cystathionine beta-synthase gene and myelomeningocele. ACTA ACUST UNITED AC 2011; 94:52-6. [PMID: 21957013 DOI: 10.1002/bdra.22855] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 12/24/2022]
Abstract
BACKGROUND Among infants born with spina bifida, the most common defect is myelomeningocele (MM). The prevention of MM by maternal periconceptional folic acid (FA) supplementation has been studied extensively. The protective effect provided by FA suggests that the genes involved in folate metabolism, such as cystathionine beta-synthase (CBS), warrant further investigation. METHODS This study sequenced the DNA from 96 patients with MM to identify novel potential disease-causing variants across the 17 exons of the CBS gene. The frequencies of known single nucleotide polymorphisms (SNPs) were identified, and sequences that differed from the reference sequences were considered novel variants. Statistical analysis was performed using two-sided Fisher's exact test to compare frequencies of SNPs between groups of patients and the known population frequencies. RESULTS We found a new variant in exon 3 in one patient that results in a G/A change subsequently encoding a stop codon. In addition, we found a new variant in the 3'-UTR of exon 17. Allele frequencies for 10 known single nucleotide polymorphisms (SNPs) were determined: rs234706, rs72058776, rs1801181, rs6582281, rs71872941, rs12613, rs706208, rs706209, rs73906420, and rs9982921. Of the remaining 48 known SNPs, all tested DNAs were homozygous for the major allele. CONCLUSION We identified a previously undescribed variant in exon 3 that encodes a stop codon, thus halting downstream translation of the CBS protein. According to the Human Splicing Finder, the 3'-UTR variant found in exon 17 is predicted to abolish the recognition sites for two splice binding factors, SRp40 and SF2/ASF. The functional significance of the 3'-UTR mutation needs to be investigated.
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Affiliation(s)
- Melissa M Tilley
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics The University of Texas Medical School at Houston, Houston, Texas 77030, USA
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Wilffert B, Altena J, Tijink L, van Gelder MMHJ, de Jong-van den Berg LTW. Pharmacogenetics of drug-induced birth defects: what is known so far? Pharmacogenomics 2011; 12:547-58. [PMID: 21521026 DOI: 10.2217/pgs.10.201] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A literature review was performed to collect information on the role of pharmacogenetics in six proposed teratogenic mechanisms associated with drug use during pregnancy: folate antagonism, oxidative stress, angiotensin-converting enzyme inhibition and angiotensin II receptor antagonism, cyclooxygenase-1 and -2 inhibition, 5-hydroxytryptamine-reuptake inhibition and drug transporters in the placenta. Data on the direct relationship between pharmacogenetics and drug-induced birth defects were found for folate metabolism, oxidative stress caused by phenytoin exposure and drug transporters in the placenta. Although no specific data to support pharmacogenetic-related birth defects were found for the NSAIDs, paroxetine and fluoxetine, it might be expected that polymorphisms modify their teratogenic effects. The usually low prevalence of drug-induced malformations impedes the demonstration of the contribution of pharmacogenetics. Large-scale studies, preferably case-control studies, are needed.
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Affiliation(s)
- Bob Wilffert
- Unit of Pharmacoepidemiology & Pharmacoeconomics, Department of Pharmacy, University of Groningen, Groningen 9713AV, The Netherlands.
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Gan YY, Chen CF. Novel alleles of 31-bp VNTR polymorphism in the human cystathionine β-synthase (CBS) gene were detected in healthy Asians. J Genet 2011; 89:449-55. [PMID: 21273695 DOI: 10.1007/s12041-010-0063-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A 31-bp variable number of tandem repeats (VNTR) polymorphism of the cystathionine β-synthase (CBS) gene was earlier reported in Caucasians of predominantly European descent and Indo-Caucasoid populations. We report here for the first time, the detection of allele 20, which was absent in Caucasian and Indo-Caucasoid populations, as a common allele present in Singaporean Chinese (6.25%), Indians (11.7%), and Malays (11.5%). Hence, allele 20 might be a specific allele for Asian populations. A relatively common allele 19 found in the Caucasian and Indo-Caucasoid populations (10.4%-10.6%) was absent in the Asian samples of this study. Therefore, allele 19 might be a specific allele for the Caucasian populations. A novel and rare allele 13, which was not reported before in the Caucasian and Indo-Caucasoid populations, was found in 0.5% of Singaporean Chinese as genotype 13/17 heterozygotes. The presence of alleles 13 and 20 were verified by DNA sequencing. There were five new genotypes (13/17, 16/20, 17/20, 18/20 and 20/20) not reported before in the Caucasian and Indo-Caucasoid populations, detected in this study. Nine genotypes (15/18, 16/18, 16/21, 17/19, 18/19, 18/21, 19/19, 19/21 and 21/21) which were present in the Caucasian and/or Indo-Caucasoid populations were absent in this study. Our results showed that CBS 31-bp VNTR polymorphism has a distinct genetic difference in allele and genotype frequencies between the European Caucasians, Indo-Caucasoid and Asian populations.
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Affiliation(s)
- Yik-Yuen Gan
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University,1 Nanyang Walk, Singapore 637616, Republic of Singapore.
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Molloy AM, Brody LC, Mills JL, Scott JM, Kirke PN. The search for genetic polymorphisms in the homocysteine/folate pathway that contribute to the etiology of human neural tube defects. ACTA ACUST UNITED AC 2009; 85:285-94. [PMID: 19235830 DOI: 10.1002/bdra.20566] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In this paper, we trace the history of current research into the genetic and biochemical mechanisms that underlie folate-preventable neural tube defects (NTDs). The inspired suggestion by Smithells that common vitamins might prevent NTDs ignited a decade of biochemical investigations-first exploring the nutritional and metabolic factors related to NTDs, then onto the hunt for NTD genes. Although NTDs were known to have a strong genetic component, the concept of common genetic variance being linked to disease risk was relatively novel in 1995, when the first folate-related polymorphism associated with NTDs was discovered. The realization that more genes must be involved started a rush to find polymorphic needles in genetic haystacks. Early efforts entailed the intellectually challenging and time-consuming task of identifying and analyzing candidate single nucleotide polymorphisms (SNPs) in folate pathway genes. Luckily, human genome research has developed rapidly, and the search for the genetic factors that contribute to the etiology of human NTDs has evolved to mirror the increased level of knowledge and data available on the human genome. Large-scale candidate gene analysis and genome-wide association studies are now readily available. With the technical hurdles removed, the remaining challenge is to gather a sample large enough to uncover the polymorphisms that contribute to NTD risk. In some respects the real work is beginning. Although moving forward is exciting, it is humbling that the most important result-prevention of NTDs by maternal folic acid supplementation-was achieved years ago, the direct result of Smithells' groundbreaking studies.
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Affiliation(s)
- Anne M Molloy
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland.
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Abstract
This review provides a brief description of folate use and folic acid metabolism in relation to neural tube defect (NTD) risk. First, a meta-analysis of reduction in NTD recurrence and occurrence risk with periconceptional folic acid supplementation is presented. Second, an overview of the complex folate metabolism is given. Third, SNPs for genes involved in folate and homocysteine metabolism that have been studied in relation to NTD riskare discussed. Fourth, the questions whether folate receptor autoantibodies or hampered methylation are mechanisms underlying NTDs are briefly discussed.
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Affiliation(s)
- Henk J Blom
- Metabolic Unit, Department of Clinical Chemistry, Free University Medical Center Amsterdam, Amsterdam, The Netherlands.
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Beaudin AE, Stover PJ. Folate-mediated one-carbon metabolism and neural tube defects: balancing genome synthesis and gene expression. ACTA ACUST UNITED AC 2007; 81:183-203. [PMID: 17963270 DOI: 10.1002/bdrc.20100] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Neural tube defects (NTDs) refer to a cluster of neurodevelopmental conditions associated with failure of neural tube closure during embryonic development. Worldwide prevalence of NTDs ranges from approximately 0.5 to 60 per 10,000 births, with regional and population-specific variation in prevalence. Numerous environmental and genetic influences contribute to NTD etiology; accumulating evidence from population-based studies has demonstrated that folate status is a significant determinant of NTD risk. Folate-mediated one-carbon metabolism (OCM) is essential for de novo nucleotide biosynthesis, methionine biosynthesis, and cellular methylation reactions. Periconceptional maternal supplementation with folic acid can prevent occurrence of NTDs in the general population by up to 70%; currently several countries fortify their food supply with folic acid for the prevention of NTDs. Despite the unambiguous impact of folate status on NTD risk, the mechanism by which folic acid protects against NTDs remains unknown. Identification of the mechanism by which folate status affects neural tube closure will assist in developing more efficacious and better targeted preventative measures. In this review, we summarize current research on the relationship between folate status and NTDs, with an emphasis on linking genetic variation, folate nutriture, and specific metabolic and/or genomic pathways that intersect to determine NTD outcomes.
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Affiliation(s)
- Anna E Beaudin
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
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van der Linden IJM, Afman LA, Heil SG, Blom HJ. Genetic variation in genes of folate metabolism and neural-tube defect risk. Proc Nutr Soc 2006; 65:204-15. [PMID: 16672082 DOI: 10.1079/pns2006495] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Neural-tube defects (NTD) are common congenital malformations that can lead to severe disability or even death. Periconceptional supplementation with the B-vitamin folic acid has been demonstrated to prevent 50-70% of NTD cases. Since the identification of the first genetic risk factor of NTD, the C677T single-nucleotide polymorphism (SNP) in the methylenetetrahydrofolate reductase (MTHFR) gene, and the observation that elevated plasma homocysteine levels are associated with NTD, research has focused on genetic variation in genes encoding for enzymes of folate metabolism and the closely-related homocysteine metabolism. In the present review relevant SNP in genes that code for enzymes involved in folate transport and uptake, the folate cycles and homocysteine metabolism are summarised and the importance of these SNP discussed in relation to NTD risk.
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Affiliation(s)
- Ivon J M van der Linden
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Center, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Boyles AL, Billups AV, Deak KL, Siegel DG, Mehltretter L, Slifer SH, Bassuk AG, Kessler JA, Reed MC, Nijhout HF, George TM, Enterline DS, Gilbert JR, Speer MC. Neural tube defects and folate pathway genes: family-based association tests of gene-gene and gene-environment interactions. ENVIRONMENTAL HEALTH PERSPECTIVES 2006; 114:1547-52. [PMID: 17035141 PMCID: PMC1626421 DOI: 10.1289/ehp.9166] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
BACKGROUND Folate metabolism pathway genes have been examined for association with neural tube defects (NTDs) because folic acid supplementation reduces the risk of this debilitating birth defect. Most studies addressed these genes individually, often with different populations providing conflicting results. OBJECTIVES Our study evaluates several folate pathway genes for association with human NTDs, incorporating an environmental cofactor: maternal folate supplementation. METHODS In 304 Caucasian American NTD families with myelomeningocele or anencephaly, we examined 28 polymorphisms in 11 genes: folate receptor 1, folate receptor 2, solute carrier family 19 member 1, transcobalamin II, methylenetetrahydrofolate dehydrogenase 1, serine hydroxymethyl-transferase 1, 5,10-methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homo-cysteine methyltransferase, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase, betaine-homocysteine methyltransferase (BHMT), and cystathionine-beta-synthase. RESULTS Only single nucleotide polymorphisms (SNPs) in BHMT were significantly associated in the overall data set; this significance was strongest when mothers took folate-containing nutritional supplements before conception. The BHMT SNP rs3733890 was more significant when the data were stratified by preferential transmission of the MTHFR rs1801133 thermolabile T allele from parent to offspring. Other SNPs in folate pathway genes were marginally significant in some analyses when stratified by maternal supplementation, MTHFR, or BHMT allele transmission. CONCLUSIONS BHMT rs3733890 is significantly associated in our data set, whereas MTHFR rs1801133 is not a major risk factor. Further investigation of folate and methionine cycle genes will require extensive SNP genotyping and/or resequencing to identify novel variants, inclusion of environmental factors, and investigation of gene-gene interactions in large data sets.
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Affiliation(s)
- Abee L. Boyles
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Ashley V. Billups
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Kristen L. Deak
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Deborah G. Siegel
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Lorraine Mehltretter
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Susan H. Slifer
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Alexander G. Bassuk
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - John A. Kessler
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | | | | | | | - David S. Enterline
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - John R. Gilbert
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
| | - Marcy C. Speer
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina, USA
- Address correspondence to M.C. Speer, Duke University Medical Center, Box 3445, Durham, NC 27710 USA. Telephone: (919) 684-2702. Fax: (919) 684-0917. E-mail:
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Castro R, Rivera I, Blom HJ, Jakobs C, Tavares de Almeida I. Homocysteine metabolism, hyperhomocysteinaemia and vascular disease: an overview. J Inherit Metab Dis 2006; 29:3-20. [PMID: 16601863 DOI: 10.1007/s10545-006-0106-5] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Accepted: 08/31/2005] [Indexed: 11/26/2022]
Abstract
Hyperhomocysteinaemia has been regarded as a new modifiable risk factor for atherosclerosis and vascular disease. Homocysteine is a branch-point intermediate of methionine metabolism, which can be further metabolised via two alternative pathways: degraded irreversibly through the transsulphuration pathway or remethylated to methionine by the remethylation pathway. Both pathways are B-vitamin-dependent. Plasma homocysteine concentrations are determined by nongenetic and genetic factors. The metabolism of homocysteine, the role of B vitamins and the contribution of nongenetic and genetic determinants of homocysteine concentrations are reviewed. The mechanisms whereby homocysteine causes endothelial damage and vascular disease are not fully understood. Recently, a link has been postulated between homocysteine, or its intermediates, and an alterated DNA methylation pattern. The involvement of epigenetic mechanisms in the context of homocysteine and atherosclerosis, due to inhibition of transmethylation reactions, is briefly overviewed.
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Affiliation(s)
- R Castro
- Centro de Patogénese Molecular, Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, Lisbon 1649-003, Portugal
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Sharma P, Senthilkumar RD, Brahmachari V, Sundaramoorthy E, Mahajan A, Sharma A, Sengupta S. Mining literature for a comprehensive pathway analysis: a case study for retrieval of homocysteine related genes for genetic and epigenetic studies. Lipids Health Dis 2006; 5:1. [PMID: 16430779 PMCID: PMC1395315 DOI: 10.1186/1476-511x-5-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 01/23/2006] [Indexed: 02/07/2023] Open
Abstract
Homocysteine is an independent risk factor for cardiovascular diseases. It is also known to be associated with a variety of complex disorders. While there are a large number of independent studies implicating homocysteine in isolated pathways, the mechanism of homocysteine induced adverse effects are not clear. Homocysteine-induced modulation of gene expression through alteration of methylation status or by hitherto unknown mechanisms is predicted to lead to several pathological conditions either directly or indirectly. In the present manuscript, using literature mining approach, we have identified the genes that are modulated directly or indirectly by an elevated level of homocysteine. These genes were then placed in appropriate pathways in an attempt to understand the molecular basis of homocysteine induced complex disorders and to provide a resource for selection of genes for polymorphism screening and analysis of mutations as well as epigenetic modifications in relation to hyperhomocysteinemia. We have identified 135 genes in 1137 abstracts that either modulate the levels of homocysteine or are modulated by elevated levels of homocysteine. Mapping the genes to their respective pathways revealed that an elevated level of homocysteine leads to the atherosclerosis either by directly affecting lipid metabolism and transport or via oxidative stress and/or Endoplasmic Reticulum (ER) stress. Elevated levels of homocysteine also decreases the bioavailability of nitric oxide and modulates the levels of other metabolites including S-adenosyl methionine and S-adenosyl homocysteine which may result in cardiovascular or neurological disorders. The ER stress emerges as the common pathway that relates to apoptosis, atherosclerosis and neurological disorders and is modulated by levels of homocysteine. The comprehensive network collated has lead to the identification of genes that are modulated by homocysteine indicating that homocysteine exerts its effect not only through modulating the substrate levels for various catalytic processes but also through regulation of expression of genes involved in complex diseases.
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Affiliation(s)
- Priyanka Sharma
- Department of Proteomics and Structural Biology, Institute of Genomics and Integrative Biology, Mall Road, Delhi-110007, India
- Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi-110007, India
| | - RD Senthilkumar
- Department of Proteomics and Structural Biology, Institute of Genomics and Integrative Biology, Mall Road, Delhi-110007, India
| | - Vani Brahmachari
- Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi-110007, India
| | - Elayanambi Sundaramoorthy
- Department of Proteomics and Structural Biology, Institute of Genomics and Integrative Biology, Mall Road, Delhi-110007, India
| | - Anubha Mahajan
- Department of Proteomics and Structural Biology, Institute of Genomics and Integrative Biology, Mall Road, Delhi-110007, India
| | - Amitabh Sharma
- Department of Proteomics and Structural Biology, Institute of Genomics and Integrative Biology, Mall Road, Delhi-110007, India
| | - Shantanu Sengupta
- Department of Proteomics and Structural Biology, Institute of Genomics and Integrative Biology, Mall Road, Delhi-110007, India
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Picker JD, Coyle JT. Do maternal folate and homocysteine levels play a role in neurodevelopmental processes that increase risk for schizophrenia? Harv Rev Psychiatry 2005; 13:197-205. [PMID: 16126606 DOI: 10.1080/10673220500243372] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Evidence from many different lines of research supports the hypothesis that schizophrenia is a disorder of development with etiological factors implicated as early as the second trimester in utero. We suggest that low maternal folate, acting to increase homocysteine levels, may provide a functional link between many of the identified prenatal risk factors and the hypothesized mechanisms whereby neurodevelopmental patterning deviates toward a schizophrenic potential. METHODS PubMed was searched from the present back to 1963, when elevated homocysteine was identified as a pathogen in homocystinuria as first described by Carson and colleagues (Arch Dis Child 1963;38:425-36). All articles for homocystinuria, homocysteine, folate, and development with schizophrenia were evaluated. RESULTS The findings from this review support the hypothesis that maternal low folate and high homocysteine levels may provide a potential teratogenic mechanism that increases the risk for developing schizophrenia. CONCLUSION The potential role of maternal folate deficiency and hyperhomocystinemia in the genesis of schizophrenia would extend the range of their known teratogenic effects. Given the potential for preventive treatment offered by this hypothesis, we believe further investigation into this mechanism is warranted.
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Affiliation(s)
- Jonathan D Picker
- Department of Genetics, Harvard Medical School; McLean Hospital, Belmont, MA, USA.
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Relton CL, Wilding CS, Laffling AJ, Jonas PA, Burgess T, Binks K, Tawn EJ, Burn J. Low erythrocyte folate status and polymorphic variation in folate-related genes are associated with risk of neural tube defect pregnancy. Mol Genet Metab 2004; 81:273-81. [PMID: 15059614 DOI: 10.1016/j.ymgme.2003.12.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Accepted: 12/22/2003] [Indexed: 11/30/2022]
Abstract
Previous studies have shown conflicting findings in linking polymorphic variation in folate-related genes to the risk of neural tube defect pregnancy. Recent evidence points to maternal genotype being important in determining NTD risk. A case-control study was undertaken in 97 mothers of NTD cases from the northern region of the UK. Pregnant controls (n = 190) from a regional DNA bank and non-pregnant controls (n = 100) from the same geographical area were recruited. MTHFR 677C >T, MTHFR 1298A >C, MTRR 66A >G, SHMT 1420C >T, CbetaS 844ins68, and RFC-1 80G >A allele and genotype frequencies were determined and odds ratios (OR) calculated. Erythrocyte folate levels for cases and controls were also measured and a comparison made of median erythrocyte folate levels stratified according to genotype. The MTHFR 677C >T variant was not shown to be an independent NTD risk factor in mothers of NTD-affected pregnancy. A second polymorphism in MTHFR, 1298A >C, was less frequently observed in mothers of NTD cases (OR [95% CI]=0.57 [0.33, 0.97]). Possession of compound 1298A >C and 677C >T variants elevated risk of NTD pregnancy considerably (TT/AC+TT/CC vs CC/AA OR [95% CI]=6.56 [1.10, 39.33]). Erythrocyte folate levels were persistently lower in NTD mothers (p = 0.001) despite assays being conducted many years after the index pregnancy (17.6+/-12.6 years). Erythrocyte folate levels were depressed in the presence of the MTHFR 677C >T variant.
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Affiliation(s)
- Caroline L Relton
- Paediatric and Lifecourse Epidemiology Research Group, School of Clinical Medical Sciences (Child Health), Newcastle University, Sir James Spence Institute, Royal Victoria Infirmary, Newcastle upon Tyne NE2 4LP, UK.
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