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Khalil A, Khan HN, Wasim M, Ayesha H, Awan FR. Development of low-cost in-house tetra-ARMS-PCR assay for the screening of five CBS mutations found in Pakistani homocystinuria patients. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2023; 43:517-529. [PMID: 37971987 DOI: 10.1080/15257770.2023.2280013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023]
Abstract
BACKGROUND Classical homocystinuria is an inborn amino acid metabolism disorder resulting from mutations in the Cystathionine-β-Synthase (CBS) gene. These mutations lead to elevated homocysteine and methionine levels and reduced cysteine levels in the blood. Typically, diagnosis occurs after patients display symptoms, and various lab methods confirm it. DNA sequencing is the best option for early detection of genetic variants in asymptomatic suspected individuals. Unfortunately, its high cost can hinder its use, especially in low-income countries like Pakistan. OBJECTIVE Aim of this study was to devise a robust low-cost diagnostic/screening assay based on Tetra-ARMS-PCR for five prevalent genetic variants found in Pakistani classical homocystinuria patients. MATERIALS AND METHODS In the current study, T-ARMS-PCR assays were developed for five mutations (c.975G > C, c.770C > T, c.752T > C, c.1039 + 1G > T, c.451 + 1GG > TA), which were characterized previously in classical homocystinuria patients. These low-cost T-ARMS-PCR assays were then used to screen the affected individuals and their family members to identify their genotypes for pathogenic variations in the asymptomatic patients and carriers in their respective families. RESULTS The outcomes were entirely consistent with those obtained from Sanger DNA sequencing, confirming the sensitivity, specificity, and reliability of the T-ARMS-PCR assay for detecting CBS mutations. CONCLUSION T-ARMS-PCR has wide applications for low-income countries for the screening and early diagnosis of asymptomatic patients and carriers in the homocystinuria affected families as well as other inherited diseases.
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Affiliation(s)
- Adila Khalil
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
- NIBGE College, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Haq Nawaz Khan
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
- NIBGE College, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
- Biological and Biomedical Sciences, The Aga Khan University, Karachi, Pakistan
| | - Muhammad Wasim
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
- NIBGE College, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
- Biological and Biomedical Sciences, The Aga Khan University, Karachi, Pakistan
| | - Hina Ayesha
- Department of Pediatrics, Punjab Medical College, Faisalabad Medical University, Faisalabad, Pakistan
| | - Fazli Rabbi Awan
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
- NIBGE College, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
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Seven novel genetic variants in a North Indian cohort with classical homocystinuria. Sci Rep 2020; 10:17299. [PMID: 33057012 PMCID: PMC7560719 DOI: 10.1038/s41598-020-73475-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 09/08/2020] [Indexed: 01/21/2023] Open
Abstract
Classical homocystinuria is the most common cause of isolated homocystinuria. The variants of the CBS gene remain unidentified in Indian children with this disorder. Based on the hallmark clinical features, family history, and/or biochemical clues for classical homocystinuria, 16 children below the age of 18 years were evaluated by Sanger sequencing of the coding exons of CBS gene with flanking intronic regions. The common C677T variant of the MTHFR gene was also screened by restriction fragment length polymorphism. Fifteen children were clinically suspected of having classical homocystinuria and one asymptomatic child with positive family history. Only seven children had biochemical features of classical homocystinuria. Sanger sequencing of the CBS gene confirmed 15 different pathogenic or likely pathogenic variants in 14 cases. Of these, seven variants were novel (three frameshift deletions, two nonsense, one missense, one splice site variant) and were predicted to be deleterious by Mutation Taster software. Seven cases were homozygous, another six were compound heterozygous, and one case was single heterozygous in the study. None of the three most frequent mutations reported worldwide viz., I278T, G307S, and IVS 11-2A>C were found in our cohort. No variants were detected in the exons 2, 8, 12, and 14 as compared to reported literature. Eleven out of 15 variants were associated with the conserved catalytic domain of the CBS polypeptide. The MTHFR polymorphism C677T was observed in heterozygous state in six cases. Our study reports the detailed genotype and seven novel variants in the CBS gene, causing classical homocystinuria in Indian children. The genetic analysis will help to offer accurate genetic counseling, prenatal diagnosis, and development of mutation-based novel therapeutic strategies.
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Paul R, Borah A. L-DOPA-induced hyperhomocysteinemia in Parkinson's disease: Elephant in the room. Biochim Biophys Acta Gen Subj 2016; 1860:1989-97. [DOI: 10.1016/j.bbagen.2016.06.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 05/20/2016] [Accepted: 06/14/2016] [Indexed: 02/08/2023]
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Murthy J, Lakkakula S, Gurramkonda VB, Pathapati RM, Maram R, Lakkakula BVKS. CBS c.844ins68 Polymorphism Frequencies in Control Populations: Implications on Nonsyndromic Cleft Lip With or Without Cleft Palate. Cleft Palate Craniofac J 2014; 52:49-53. [PMID: 24437588 DOI: 10.1597/13-051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common birth defect with substantial clinical and social impact. Folate deficiency is one of the factors that have been associated with increased risk for NSCLP. Polymorphisms in folate and homocysteine pathway genes may act as susceptibility factors. OBJECTIVE The objective of this study was to evaluate prevalence estimates of cystathionine beta-synthase (CBS) insertion of 68-bp (c.844ins68) polymorphisms and their correlation with NSCLP. MATERIAL AND METHODS A total of 236 unrelated individuals from seven Indian populations and an additional 355 cases with NSCLP and 357 controls without NSCLP were included in this study. We investigated the CBS c.844ins68 polymorphism in all samples. Genotyping was performed with polymerase chain reaction and electrophoresis. The data were statistically analyzed using the chi-square test. RESULTS The CBS c.844ins68 allele is present in six of the seven populations analyzed, and allele frequencies range from 1.5% in Balija to 9.1% in Sugali populations. The CBS c.844ins68 polymorphism showed a significant protective effect on NSCLP at both genotype (WW versus WI: odds ratio [OR] = 0.54, 95% confidence interval [CI] = 0.31 to 0.95, P = .149) and allele levels (W versus I: OR = 0.56, 95% CI = 0.32 to 0.96, P = .033). CONCLUSIONS The current study observed significant differences in the frequency of the CBS 844ins68 allele across populations. There is a significant association between CBS c.844ins68 polymorphism and cleft lip and palate in the Indian population. Additional studies are warranted to identify the functional variants in the genes controlling homocysteine as etiological contributors to the formation of oral clefts.
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Casique L, Kabil O, Banerjee R, Martinez JC, De Lucca M. Characterization of two pathogenic mutations in cystathionine beta-synthase: different intracellular locations for wild-type and mutant proteins. Gene 2013; 531:117-24. [PMID: 23981774 DOI: 10.1016/j.gene.2013.08.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 06/26/2013] [Accepted: 08/07/2013] [Indexed: 10/26/2022]
Abstract
Cystathionine β-synthase (CBS) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the condensation of homocysteine with serine to generate cystathionine. Homocystinuria is an autosomal recessive disorder commonly caused by a deficiency of CBS activity. Here, we characterized a novel CBS mutation (c.260C>A (p.T87N)) and a previously reported variant (c.700G>A (p.D234N)) found in Venezuelan homocystinuric patients, one nonresponsive and one responsive to vitamin B6. Both mutant proteins were expressed in vitro in prokaryotic and eukaryotic cells, finding lower soluble expression in HEK-293 cells (19% T87N and 23% D234N) compared to wild-type CBS. Residual activities obtained for the mutant proteins were 3.5% T87N and 43% D234N. Gel exclusion chromatography demonstrated a tendency of the T87N mutant to aggregate while the distribution of the D234N mutant was similar to wild-type enzyme. Using immunofluorescence microscopy, an unexpected difference in intracellular localization was observed between the wild-type and mutant proteins. While the T87N mutant exhibited a punctate appearance, the wild-type protein was homogeneously distributed inside the cell. Interestingly, the D234N protein showed both distributions. This study demonstrates that the pathogenic CBS mutations generate unstable proteins that are unable (T87N) or partially unable (D234N) to assemble into a functional enzyme, implying that these mutations might be responsible for the homocystinuria phenotype.
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Affiliation(s)
- L Casique
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas 1081-A, Venezuela; Laboratorio de Estudio Molecular de Enfermedades Hereditarias, Fundación IDEA, Caracas 1080-A, Venezuela.
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Antiepileptic drugs, hyperhomocysteinemia and B-vitamins supplementation in patients with epilepsy. Epilepsy Res 2012; 102:1-7. [DOI: 10.1016/j.eplepsyres.2012.07.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 06/20/2012] [Accepted: 07/03/2012] [Indexed: 11/20/2022]
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Saxena AK, Gupta J, Pandey S, Gangopadhaya AN, Pandey LK. Prevalence of cystathionine beta synthase gene mutation 852Ins68 as a possible risk for neural tube defects in eastern India. GENETICS AND MOLECULAR RESEARCH 2011; 10:2424-9. [PMID: 22002135 DOI: 10.4238/2011.october.7.4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cystathionine beta synthase gene (CβS) catalyzes the condensation of homocysteine with serine, forming cystathionine by the transsulfuration pathway. Disruption of CβS enzyme activity due to defective folic acid metabolism increases the risk factor for neural tube defects. We evaluated the CβS gene mutation in 25 children with neural tube defects (NTDs), including lumbosacral and thoracic myelomeningocele and open NTDs and mothers of cases, along with 25 healthy children and their mothers, serving as controls. Genomic DNA was isolated to assess the polymorphism of 852Ins68 in the CβS gene using PCR-RFLP analysis and nucleotide sequencing techniques. The 68-bp insertion was observed in one of the 25 NTD cases (lumbosacral myelomeningocele), and in two of the mothers of NTD cases. Statistical analysis was carried out using the Fischer exact probability test, which showed a lack of significance (P > 0.05), but the odds ratio of 2.08 with 95% confidence interval of 0.17-24.6 in NTDs mother was quite high because of the small sample size. However, the study was further extended to find out the involvement of specific nucleotide sequences, which again confirmed the 852Ins68 insertion and replacement of nucleotides (TCCAT to GGGG) in lumbosacral myelomeningocele (due to other category of NTDs), suggesting that it could be an independent risk factor for birth defects, including NTDs.
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Affiliation(s)
- A K Saxena
- Center of Experimental Medicine and Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
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Dayal S, Lentz SR. Murine models of hyperhomocysteinemia and their vascular phenotypes. Arterioscler Thromb Vasc Biol 2008; 28:1596-605. [PMID: 18556571 DOI: 10.1161/atvbaha.108.166421] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hyperhomocysteinemia is an established risk factor for arterial as well as venous thromboembolism. Individuals with severe hyperhomocysteinemia caused by inherited genetic defects in homocysteine metabolism have an extremely high incidence of vascular thrombosis unless they are treated aggressively with homocysteine-lowering therapy. The clinical value of homocysteine-lowering therapy in individuals with moderate hyperhomocysteinemia, which is very common in populations at risk for vascular disease, is more controversial. Considerable progress in our understanding of the molecular mechanisms underlying the association between hyperhomocysteinemia and vascular thrombotic events has been provided by the development of a variety of murine models. Because levels of homocysteine are regulated by both the methionine and folate cycles, hyperhomocysteinemia can be induced in mice through both genetic and dietary manipulations. Mice deficient in the cystathionine beta-synthase (CBS) gene have been exploited widely in many studies investigating the vascular pathophysiology of hyperhomocysteinemia. In this article, we review the established murine models, including the CBS-deficient mouse as well as several newer murine models available for the study of hyperhomocysteinemia. We also summarize the major vascular phenotypes observed in these murine models.
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Affiliation(s)
- Sanjana Dayal
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, USA
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Weir DG, Scott JM. Homocysteine as a risk factor for cardiovascular and related disease: nutritional implications. Nutr Res Rev 2007; 11:311-38. [DOI: 10.1079/nrr19980020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
AbstractThe objectives were firstly to assess the evidence that homocysteine is a significant and independent risk factor for vascular disease with special reference to cardiovascular disease, and secondly to evaluate the evidence that a food staple fortified with folic acid will reduce this problem on a population basis.The structure of plasma homocysteine (tHcy) is described. Homocysteine, a highly reactive compound, is synthesized from the amino acid, methionine, and is metabolized by two pathways, the catabolic transsulphuration routeviacystathionine β-synthase (EC 4.2.1.22) and the remethylation path using 5-methyltetrahy-drofolate polyglutamate, the product of 5,10-methylenetetrahydrofolate reductase (MTHFR; EC 1.1.1.171),viathe cobalamin dependent enzyme, methionine synthase (MS; EC 2.1.1.13).The mechanisms whereby hyper-tHcy is produced include both increased rates of synthesis and decreased metabolism. The latter may occur owing to nutritional deficiency of the vitamin cofactors which are necessary for the normal function of the metabolic enzymes. In particular, folate is required for methylene reductase, pyridoxal phosphate for cystathionine synthase and cobalamin for methionine synthase. When these vitamins are deficient hyper-tHcy is induced and this occurs especially in the elderly. Alternatively, a variant form of methylene reductase has recently been described which occurs in nearly 10% of the normal population. This variant is associated with hyper-tHcy, especially in situations associated with a low folate nutritional status.Meta-analysis of both retrospective case-control studies, nested prospective case-control surveys and a secondary trial of mortality in postmyocardial infarct patients have shown that the association of hyper-tHcy with vascular disease is beyond doubt. This has been further supported by direct assessments of the degree of vascular disease in the carotid brachial and aortic arteries in relation to tHcy levels. Furthermore, treatment with a cocktail of the vitamin cofactors has produced lowering of tHcy levels and regression of the vascular disease in the carotid arteries of affected individuals.Suggested pathogenic mechanisms in vascular disease induced by hyper-tHcy include vascular endothelial cell dysfunction, smooth muscle proliferation and derangements of normal intravascular regulation mechanisms. A variety of clinical conditions are known to be associated with a high incidence of thromboembolic complications. Some of these are associated with hyper-tHcy.Low physiological doses of folic acid, as well as pharmocological doses, lower tHcy. However, because of the poor bioavailability of food folate (50%) and the considerable chemical instability of the naturally occurring reduced forms of folate, in most people it would require unacceptably high consumption of green vegetables to accomplish the necessary increase in intracellular folate and reduction in tHcy. Accordingly, folic acid, the nonreduced synthetic form of the vitamin, which is 100% bioavailable and chemically extremely stable, should be added to a food staple such as flour to ensure maximum protection for most of the population.
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Hamelet J, Aït-Yahya-Graison E, Matulewicz E, Noll C, Badel-Chagnon A, Camproux AC, Demuth K, Paul JL, Delabar JM, Janel N. Homocysteine threshold value based on cystathionine beta synthase and paraoxonase 1 activities in mice. Eur J Clin Invest 2007; 37:933-8. [PMID: 17971175 DOI: 10.1111/j.1365-2362.2007.01879.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Hyperhomocysteinaemia is a metabolic disorder associated with the development of premature atherosclerosis. Among the determinants which predispose to premature thromboembolic and atherothrombotic events, serum activity of paraoxonase 1, mainly synthesized in the liver, has been shown to be a predictor of cardiovascular disease and to be negatively correlated with serum homocysteine levels in human. Even though treatments of hyperhomocysteinaemic patients ongoing cardiovascular complications are commonly used, it still remains unclear above which homocysteine level a preventive therapy should be started. MATERIALS AND METHODS In order to establish a threshold of plasma homocysteine concentration we have analyzed the hepatic cystathionine beta synthase and paraoxonase 1 activities in a moderate to intermediate murine model of hyperhomocysteinaemia. Using wild type and heterozygous cystathionine beta synthase deficient mice fed a methionine enriched diet or a control diet, we first studied the link between cystathionine beta synthase and paraoxonase 1 activities and plasma homocysteine concentration. RESULTS Among the animals used in this study, we observed a negative correlation between plasma homocysteine level and cystathionine beta synthase activity (rho=-0.52, P=0.0008) or paraoxonase 1 activity (rho=-0.49, P=0.002). Starting from these results, a homocysteine cut-off value of 15 microm has been found for both cystathionine beta synthase (P=0.0003) and paraoxonase 1 (P=0.0007) activities. CONCLUSIONS Our results suggest that both cystathionine beta synthase and paraoxonase 1 activities are significantly decreased in mice with a plasma homocysteine value greater than 15 microm. In an attempt to set up preventive treatment for cardiovascular disease our results indicate that treatments should be started from 15 microm of plasma homocysteine.
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Affiliation(s)
- J Hamelet
- EA 3508, Université Paris Diderot-Paris 7, and Hôpital Européen Georges Pompidou, Service de Biochemie, Paris, France
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Koubaa N, Nakbi A, Smaoui M, Abid N, Chaaba R, Abid M, Hammami M. Hyperhomocysteinemia and elevated ox-LDL in Tunisian type 2 diabetic patients: Role of genetic and dietary factors. Clin Biochem 2007; 40:1007-14. [PMID: 17618615 DOI: 10.1016/j.clinbiochem.2007.05.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 05/07/2007] [Accepted: 05/18/2007] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Total plasma homocysteine (tHcy) is an emerging risk factor for the development of atherosclerosis. However, its relationship with diabetes is still unclear. OBJECTIVES We evaluated the association between tHcy levels and methylenetetrahydrofolate reductase (MTHFR) 677C-->T genotype in a type 2 diabetes mellitus (DM) population and their relationship with oxidized LDL (ox-LDL) according to dietary habits and vascular complications. DESIGN AND METHODS Eighty-six DM patients were compared to 120 healthy volunteers. RESULTS Associated higher tHcy levels and significantly higher ox-LDL levels (p<0.001) were found in DM patients compared to healthy subjects. Homozygosity for the T allele of MTHFR was more frequent in diabetics than in healthy subjects (12.8% vs. 7.2%) and it was associated with higher tHcy levels. Moreover, this elevated level was associated with significantly higher ox-LDL levels in DM patients with hypertension (p<0.05). Improving folate and vitamin C intakes could have beneficial effects on lowering the tHcy and ox-LDL levels. CONCLUSIONS The interplay of genetic and dietary factors modulates the effect of homocysteine on cardiovascular risk factors.
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Affiliation(s)
- N Koubaa
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, Avicene St., 5019 Monastir, Tunisia
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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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D'Angelo A, Mazzola G, Fermo I. Gene-gene and gene-environment interactions in mild hyperhomocysteinemia. PATHOPHYSIOLOGY OF HAEMOSTASIS AND THROMBOSIS 2005; 33:337-41. [PMID: 15692239 DOI: 10.1159/000083824] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mild/moderate hyperhomocysteinemia (HHcy), a highly prevalent condition, is independently associated with an increased risk of arterial and venous thromboembolic diseases. Early reports of the association of mild/moderate HHcy with juvenile venous thromboembolism have shown familiarity for HHcy in relatives of index cases with thrombosis. Similar to inherited thrombophilia defects, inheritance of the HHcy phenotype was accordingly retained important for the definition of HHcy as an independent risk factor for thrombosis. A number of common polymorphisms in genes coding for methylenetetrahydrofolate reductase(MTHFR), methionine-synthase, methionine-synthase reductase and cysthationine beta-synthase (CBS) have been explored for their association with homocysteine levels, fasting and post-methionine load, and with thrombotic diseases. MTHFR thermolability accounts for a 10-fold increase in the risk of mild/moderate HHcy. With the possible exception of the CBS844ins68 insertion, there is no evidence for an increased risk of HHcy for any of these polymorphisms, isolated or in association with MTHFR thermolability. Environmental factors and MTHFR thermolability are main determinants of the HHcy phenotype.If mild/moderate HHcy is a pathogenetic risk factor for thrombosis, intervention aimed to improve the vitamin status appears of major importance, irrespective of common gene polymorphisms of the homocysteine metabolism.
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Affiliation(s)
- Armando D'Angelo
- Coagulation Service and Thrombosis Research Unit, IRCCS H S.Raffaele, Milano, Italy.
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Fillon-Emery N, Chango A, Mircher C, Barbé F, Bléhaut H, Herbeth B, Rosenblatt DS, Réthoré MO, Lambert D, Nicolas JP. Homocysteine concentrations in adults with trisomy 21: effect of B vitamins and genetic polymorphisms. Am J Clin Nutr 2004; 80:1551-7. [PMID: 15585767 DOI: 10.1093/ajcn/80.6.1551] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The effects of supplementation with B vitamins and of common polymorphisms in genes involved in homocysteine metabolism on plasma total homocysteine (tHcy) concentrations in trisomy 21 are unknown. OBJECTIVES We aimed to determine the effects of orally administered folic acid and of folic acid combined with vitamin B-12, vitamin B-6, or both on tHcy in adults with trisomy 21. The study was also intended to analyze the possible influence of gene polymorphisms. DESIGN One hundred sixty adults with trisomy 21 and 160 healthy, unrelated subjects aged 26 +/- 4 y were included. Plasma tHcy, red blood cell folate, serum folate, and vitamin B-12 were measured. Genotyping for the common methylenetetrahydrofolate reductase (MTHFR) 677C-->T, MTHFR 1298A-->C, cystathionine beta-synthase 844Ins68, methionine synthase 2756A-->C, methionine synthase reductase 66A-->G, and reduced folate carrier 80G-->A polymorphisms was carried out. RESULTS The mean tHcy concentration (9.8 +/- 0.7 micromol/L) of cases who did not use vitamins was not significantly different from that of controls (9.4 +/- 0.3 micromol/L). Plasma tHcy concentrations (7.6 +/- 0.3 mmol/L) in cases who used folic acid were significantly lower than in cases who did not. Folic acid combined with vitamin B-12 did not significantly change tHcy concentrations compared with those in cases who used only folic acid. Folic acid combined with vitamins B-6 and B-12 significantly lowered tHcy (6.5 +/- 0.5 micromol/L). The difference in tHcy according to MTHFR genotype was not significant. However, tHcy concentrations were slightly higher in TT homozygotes among the controls but not among the cases. CONCLUSION This study provides information on the relation between several polymorphisms in genes involved in homocysteine and folate metabolism in adults with trisomy 21.
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Affiliation(s)
- Nathalie Fillon-Emery
- Faculté de Médecine, Laboratory of Medical Biochemistry, Vandoeuvre-Lès-Nancy, France
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Sun J, Xu Y, Zhu Y, Lu H. Genetic polymorphism of methylenetetrahydrofolate reductase as a risk factor for diabetic nephropathy in Chinese type 2 diabetic patients. Diabetes Res Clin Pract 2004; 64:185-90. [PMID: 15126006 DOI: 10.1016/j.diabres.2003.10.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/28/2003] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Genetic predisposition has been implicated in diabetic nephropathy (DN). The C677T variant of the methylenetetrahydrofolate reductase (MTHFR) gene, one of the key enzymes catalyzing remethylation of homocysteine, may play a role in the development of not only vascular disease but also diabetic microangiopathies. In this study, we examined the distribution of the MTHFR genotypes in the Chinese population and the association between the C677T variant and diabetic nephropathy. METHODS 220 unrelated patients with type 2 diabetes mellitus and 130 controls were recruited. The MTHFR genotype was analyzed by PCR followed by HinfI digestion. Plasma total homocysteine levels were measured using high-performance liquid chromatography (HPLC) with fluorescence detection. RESULTS In 130 healthy control subjects, the frequency of the mutant T allele was 30.0%, comparable to that of a Hong Kong (Chinese) population. The distribution of the three genotypes was as follows: TT genotype, 16.9%; CT genotype, 26.2%; and CC genotype, 56.9%. This genotype distribution did not differ between control subjects and type 2 diabetic patients in which 19.1% were TT, 34.5% were CT and 46.4% were CC (2=3.85, P>0.05). The frequency of the mutant T allele was 42.3% in diabetic patients with nephropathy (n=124) versus 28.6% in those without nephropathy (n=96). The genotype frequencies were TT, 21.0%; CT, 42.7%; CC, 36.3% in diabetic patients with nephropathy versus TT, 16.7%; CT, 23.9%; CC, 59.4% in those without nephropathy. The MTHFR genotype and allele frequencies were different between diabetic patients with and without nephropathy (chi2=12.27, P<0.005; chi2=8.77, P<0.005, respectively). Moreover, plasma homocysteine levels were markedly higher in individuals with TT genotype than those with CC or CT genotype. CONCLUSIONS The C677T mutation of MTHFR gene is common in the Chinese population. MTHFR C677T gene polymorphism associated with a predisposition to increased plasma homocysteine levels may represent a genetic risk factor for diabetic nephropathy in Chinese type 2 diabetic patients.
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Affiliation(s)
- Jiazhong Sun
- Department of Endocrinology, Zhongnan Hospital, Wuhan University, Wuhan 430071, China.
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16
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Devlin AM, Arning E, Bottiglieri T, Faraci FM, Rozen R, Lentz SR. Effect of Mthfr genotype on diet-induced hyperhomocysteinemia and vascular function in mice. Blood 2004; 103:2624-9. [PMID: 14630804 DOI: 10.1182/blood-2003-09-3078] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Deficiency of methylenetetrahydrofolate reductase (MTHFR) predisposes to hyperhomocysteinemia and vascular disease. We tested the hypothesis that heterozygous disruption of the Mthfr gene sensitizes mice to diet-induced hyperhomocysteinemia and endothelial dysfunction. Mthfr+/- and Mthfr+/+ mice were fed 1 of 4 diets: control, high methionine (HM), low folate (LF), or high methionine/low folate (HM/LF). Plasma total homocysteine (tHcy) was higher with the LF and HM/LF diets than the control (P < .01) or HM (P < .05) diets, and Mthfr+/- mice had higher tHcy than Mthfr+/+ mice (P < .05). With the control diet, the S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH) ratio was lower in the liver and brain of Mthfr+/- mice than Mthfr+/+ mice (P < .05). SAM/SAH ratios decreased further in Mthfr+/+ or Mthfr+/- mice fed LF or LF/HM diets (P < .05). In cerebral arterioles, endothelium-dependent dilation to 1 or 10 μM acetylcholine was markedly and selectively impaired with the HM/LF diet compared with the control diet for both Mthfr+/+ (maximum dilation 5% ± 2% versus 21% ± 4%; P < .01) and Mthfr+/- (6% ± 2% versus 21% ± 3%; P < .01) mice. These findings demonstrate that the Mthfr+/- genotype sensitizes mice to diet-induced hyperhomocysteinemia and that hyperhomocysteinemia alters tissue methylation capacity and impairs endothelial function in cerebral microvessels.
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Affiliation(s)
- Angela M Devlin
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City 52242, USA
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17
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Refsum H, Smith AD, Ueland PM, Nexo E, Clarke R, McPartlin J, Johnston C, Engbaek F, Schneede J, McPartlin C, Scott JM. Facts and Recommendations about Total Homocysteine Determinations: An Expert Opinion. Clin Chem 2004; 50:3-32. [PMID: 14709635 DOI: 10.1373/clinchem.2003.021634] [Citation(s) in RCA: 685] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractBackground: Measurement of plasma total homocysteine has become common as new methods have been introduced. A wide range of disorders are associated with increased concentrations of total homocysteine. The purpose of this review is to provide an international expert opinion on the practical aspects of total homocysteine determinations in clinical practice and in the research setting and on the relevance of total homocysteine measurements as diagnostic or screening tests in several target populations.Methods: Published data available on Medline were used as the basis for the recommendations. Drafts of the recommendations were critically discussed at meetings over a period of 3 years.Outcome: This review is divided into two sections: (a) determination of homocysteine (methods and their performance, sample collection and handling, biological determinants, reference intervals, within-person variability, and methionine loading test); and (b) risk assessment and disease diagnosis (homocystinuria, folate and cobalamin deficiencies, cardiovascular disease, renal failure, psychiatric disorders and cognitive impairment, pregnancy complications and birth defects, and screening of elderly and newborns). Each of these subsections concludes with a separate series of recommendations to assist the clinician and the research scientist in making informed decisions. The review concludes with a list of unresolved questions.
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Affiliation(s)
- Helga Refsum
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
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18
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Abstract
Homocysteine remains an enigmatic marker for vascular disease. Studies have shown hyperhomocysteinemia is a risk factor for VTE, cerebrovascular disease, and coronary artery disease. This relationship, however, has not been consistently corroborated by studies of patients with genetic polymorphisms that alter homocysteine metabolism. Studies at the molecular level reveal interactions between homocysteine, the endothelium, and the clotting system. Further investigation at the basic science level is needed to determine whether homocysteine is a marker of vascular injury and thrombotic potential or whether it plays a pathogenic role. Preliminary trials with vitamins clearly show that safe, inexpensive treatment can lower homocysteine levels. The clinical impact on decreasing vascular disease, however, has yet to be shown. Until there is evidence that treatment improves outcomes, testing for homocysteine and treating hyperhomocysteinemia will be a debatable issue. A series of vitamin intervention trials begun in 1997 will enroll tens of thousands of patients (Table 1) and will, it is hoped, provide the necessary information for developing evidence-based guidelines.
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Affiliation(s)
- Ray Lee
- Department of Internal Medicine, Division of General Internal Medicine, University of Texas Southwestern Medical School, 5323 Harry Hines Boulevard, Dallas, TX 75235-8889, USA.
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19
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Abstract
OBJECTIVE To review the role of an elevated total plasma homocysteine level (hyperhomocyst[e]inemia) in patients with venous or arterial thrombosis, as reflected by the medical literature and the consensus opinion of recognized experts in the field. DATA SOURCES Review of the medical literature, primarily from the last 10 years. DATA EXTRACTION AND SYNTHESIS The literature was reviewed to identify key points defining the condition, and the clinical study design of each article was examined. A draft manuscript was prepared and circulated prior to the conference to every participant in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia. Each of the key points and associated recommendations was then presented for discussion at the conference. Recommendations were accepted if a consensus of the 70% of the experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form. CONCLUSIONS Consensus was reached on 9 recommendations concerning the criteria for diagnosis, the method of testing, and the approach for clinical management. A major point of consensus was that no causal role of hyperhomocyst(e)inemia in venous or arterial thrombosis is yet established. Testing methods used to measure homocysteine directly are sensitive and reliable, and provide more information than does genotyping for markers linked to abnormal plasma homocysteine.
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Affiliation(s)
- Nigel S Key
- Department of Medicine, Division of Hematology, Oncology, and Transplantation, University of Minnesota, Minneapolis 55455, USA.
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20
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Baydas G, Gursu MF, Cikim G, Canpolat S, Yasar A, Canatan H, Kelestimur H. Effects of pinealectomy on the levels and the circadian rhythm of plasma homocysteine in rats. J Pineal Res 2002; 33:151-5. [PMID: 12220329 DOI: 10.1034/j.1600-079x.2002.02901.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Hyperhomocysteinemia is an independent cardiovascular risk factor. There are several factors including aging that contribute to the development of hyperhomocysteinemia. Nevertheless, the exact mechanisms causing this condition are still debated. We hypothesize that the age-related decrease in melatonin levels may be consequential in hyperhomocysteinemia. Recently, we found that plasma homocysteine (Hcy) levels are increased in pinealectomized (PINX) rats and melatonin reverses this increase. The aim of the present study was to determine if there is a circadian rhythm of plasma Hcy in rats and to examine the effect of pinealectomy on this cycle. Plasma Hcy levels demonstrated a 24-hr rhythm with a peak at 02:00 hr and a nadir at 14:00 hr in both control and PINX rats. Pinealectomy did not change the phase of the rhythm or the nocturnal elevation of plasma Hcy, but it did significantly increase mean plasma Hcy levels compared with those in controls and in rats that were sham pinealectomized (sPINX) (P < 0.05). Melatonin decreases plasma Hcy levels while causing an increase in total glutathione (tGSH). In conclusion, we speculate that decreasing levels of melatonin during aging lead to hyperhomocysteinemia and a decrease in tGSH and the latter may be one of the factors causing hyperhomocysteinemia in the elderly population.
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Affiliation(s)
- Giyasettin Baydas
- Department of Physiology, College of Medicine, Firat University, Elazýg 23119, Turkey.
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21
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Abstract
Homocysteine is an independent, modifiable risk factor for cardiovascular disease. It is an intermediate amino acid formed during the metabolism of methionine. Plasma homocysteine is normally < or = 12 micromol/L, but when elevated has many deleterious cardiovascular effects. This review explains homocysteine metabolism, the effects of elevated homocysteine, factors contributing to high homocysteine, and its measurement. Risk factors for elevated homocysteine and intervention with B vitamins are discussed. Cardiovascular nurses are encouraged to facilitate homocysteine awareness through a variety of educational means.
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Affiliation(s)
- Cindy J Warren
- College of Nursing, Kent State University, Tuscarawas Campus, New Philadelphia, OH 44663, USA
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22
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Guttormsen AB, Ueland PM, Kruger WD, Kim CE, Ose L, Følling I, Refsum H. Disposition of homocysteine in subjects heterozygous for homocystinuria due to cystathionine beta-synthase deficiency: relationship between genotype and phenotype. AMERICAN JOURNAL OF MEDICAL GENETICS 2001; 100:204-13. [PMID: 11343305 DOI: 10.1002/ajmg.1247] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have investigated 31 subjects from five unrelated families with one or more members with cystathionine beta-synthase (CBS) deficiency. On the basis of their CBS genotype, the subjects were grouped as normal (n = 11) or heterozygotes (n = 20). Based on pyridoxine effect in the probands, the heterozygotes were further classified as pyridoxine-responsive (n = 9) or non-responsive (n = 11). Heterozygous subjects had normal fasting total plasma homocysteine (tHcy), but median urinary tHcy excretion rate was significantly elevated compared to healthy controls (0.39 micromol/h vs 0.24 micromol/h, P < 0.05). An abnormal tHcy response after methionine loading identified 73% of the pyridoxine non-responsive heterozygotes, but only 33% of the pyridoxine responsive participants. The increase in cystathionine or the change in tHcy relative to cystathionine did not improve diagnostic accuracy of the methionine loading test. After Hcy loading, the maximal increase in tHcy was significantly elevated, whereas t(1/2) was normal in heterozygotes. In conclusion, a single biochemical test cannot discriminate CBS heterozygotes from controls. Abnormal tHcy response after methionine loading was the most sensitive test. Our data suggest that the urinary tHcy excretion rate is a simple, non-invasive approach for studying mild disturbances in Hcy metabolism.
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Affiliation(s)
- A B Guttormsen
- LOCUS for Homocysteine and Related Vitamins, University of Bergen, Armauer Hansens Hus, Bergen, Norway.
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23
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Tsai MY, McGovern P, Kennedy EL, Hanson NQ. Short-term variability in the measurement of plasma homocysteine, fasting and post-methionine loading. Clin Biochem 2001; 34:49-52. [PMID: 11239515 DOI: 10.1016/s0009-9120(00)00198-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVES Hyperhomocysteinemia is associated with premature cerebral, peripheral and coronary vascular disease. Evaluation of the significance of changes in plasma total homocysteine (tHcy) results obtained by analysis of serial specimens may be accomplished only by taking into account biologic (between-person and within-person) as well as analytical variation. Since the repeatability of a measurement significantly determines our ability to associate tHcy level with the presence of disease, this study was performed to evaluate various components of variation in tHcy values. DESIGN AND METHODS We report the within-person, between-person, and methodological variability of tHcy, both fasting and postmethionine load (PML) values, in 20 healthy volunteers from whom samples were drawn weekly for 4 weeks. RESULTS The short-term reliability coefficient (R) was 0.72 for fasting tHcy and 0.83 for PML tHcy. CONCLUSIONS The current study demonstrates for the first time that the short-term reliability coefficient for PML tHcy is relatively high (0.83), suggesting that an individual's PML tHcy, like fasting tHcy, is relatively constant over at least one month, and that a single measurement should provide a reasonable characterization of an individual's PML tHcy concentration.
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Affiliation(s)
- M Y Tsai
- Department of Laboratory Medicine and Pathology, University of Minnesota, Medical School, 420 Delaware St., SE, Box 609, Minneapolis, MN, USA.
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24
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Peng H, Huang Q, Li Y, Sun S, Deng X, Liu H, Qiao X. Study on the relationship between plasma homocysteine and acute cerebral vascular disease. Curr Med Sci 2000; 20:330-1. [PMID: 12840927 DOI: 10.1007/bf02888195] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2000] [Indexed: 11/25/2022]
Abstract
The levels of plasma homocysteine were determined by using high-performance liquid chromatographic method. It was found that plasma homocysteine levels were significantly higher in the patients with stroke than that in the controls. There was no correlation between plasma homocysteine levels and hypertension, smoking, concentrations of blood glucose or hypertriglyceridesemia. It was suggested that hyperhomocysteinemia may be an independent risk factor for acute cerebral vascular disease.
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Affiliation(s)
- H Peng
- Department of Neurology, Xiehe Hospital, Tongji Medical University, Wuhan 430022
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25
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26
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Tsai MY. Moderate hyperhomocysteinemia and cardiovascular disease. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 2000; 135:16-25. [PMID: 10638690 DOI: 10.1016/s0022-2143(00)70016-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M Y Tsai
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, USA
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27
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28
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Fonseca V, Guba SC, Fink LM. Hyperhomocysteinemia and the endocrine system: implications for atherosclerosis and thrombosis. Endocr Rev 1999; 20:738-59. [PMID: 10529901 DOI: 10.1210/edrv.20.5.0381] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- V Fonseca
- Department of Medicine, Tulane University Medical School, New Orleans, Louisiana 70112, USA.
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29
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Födinger M, Buchmayer H, Sunder-Plassmann G. Molecular genetics of homocysteine metabolism. MINERAL AND ELECTROLYTE METABOLISM 1999; 25:269-78. [PMID: 10681651 DOI: 10.1159/000057459] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent genetic studies have led to the characterization of molecular determinants contributing to the pathogenesis of hyperhomocysteinemia. In this article we summarize the current insights into the molecular genetics of severe, moderate and mild hyperhomocysteinemia. We will consider deficiencies of the trans-sulfuration enzyme cystathionine beta-synthase (gene symbol: CBS), and the disturbances of the remethylation enzymes 5, 10-methylenetetrahydrofolate reductase (gene symbol: MTHFR), methionine synthase (gene symbol: MTR), and the recently identified methionine synthase reductase (gene symbol: MTRR). Furthermore, we will focus on clinically important genetic polymorphisms which are highly prevalent and thus of potential general interest.
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Affiliation(s)
- M Födinger
- Department of Laboratory Medicine, Division of Molecular Biology, University of Vienna, Austria.
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30
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Tsai MY, Welge BG, Hanson NQ, Bignell MK, Vessey J, Schwichtenberg K, Yang F, Bullemer FE, Rasmussen R, Graham KJ. Genetic causes of mild hyperhomocysteinemia in patients with premature occlusive coronary artery diseases. Atherosclerosis 1999; 143:163-70. [PMID: 10208491 DOI: 10.1016/s0021-9150(98)00271-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Elevated plasma homocysteine is increasingly being recognized as a risk factor for coronary artery disease (CAD). Although there is general agreement on the importance of micronutrients and genetic predisposition to elevated plasma homocysteine, the exact influence of the known prevalent mutations in genes which regulate homocysteine metabolism is not clear. We studied 376 cases of individuals with premature CAD with respect to their fasting and post-methionine load (PML) total homocysteine (tHcy) concentrations. We also determined the presence or absence of the T833C and G919A mutations of the cystathionine-beta-synthase (CBS) gene, the C677T mutation of the methylene tetrahydrofolate reductase (MTHFR) gene, and the A2756G transition of the B12 dependent methionine synthase (MS) gene. Our objectives were therefore both to confirm the relationship of plasma homocysteine with premature CAD and to examine the importance of genetic influence on both fasting and PML homocysteine. Approximately 32% of the CAD patients had fasting hyperhomocysteinemia and 16% had PML hyperhomocysteinemia. Of these, 8.5% had both forms of hyperhomocysteinemia (combined hyperhomocysteinemia). The T133C mutation in the CBS gene and the thermolabile C677T mutation in the MTHFR gene seem to play an important role in the subset of individuals with combined hyperhomocysteinemia. The A2756G transition in the MS gene is not associated with elevated plasma tHcy. Many cases (47%) of hyperhomocysteinemia are not associated with micronutrient deficiencies, impaired renal function, and/or currently known genetic mutations. Further work is needed to study whether unknown mutations, particularly those residing in the intronic sequences of the genes involved in homocysteine metabolism, other environmental factors, or interaction of gene, nutrient, and environmental factors may be the cause of currently unexplained cases of mild hyperhomocysteinemia.
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Affiliation(s)
- M Y Tsai
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis 55455, USA.
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31
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Gallagher PM, Naughten E, Hanson NQ, Schwichtenberg K, Bignell M, Yuan M, Ward P, Yap S, Whitehead AS, Tsai MY. Characterization of mutations in the cystathionine beta-synthase gene in Irish patients with homocystinuria. Mol Genet Metab 1998; 65:298-302. [PMID: 9889017 DOI: 10.1006/mgme.1998.2771] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used single-strand conformational polymorphism and nucleotide sequencing to characterize defective cystathionine beta-synthase gene alleles in 18 independent Irish patients with homocystinuria. Six mutations were detected, three of which have been reported previously and three of which were novel. The novel mutations include T302C (L101P), C684G (N228K), and G1063C (A354P). Of the three, only T302C (L101P) was somewhat prevalent, being found in 3 of 37 independent alleles.
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Affiliation(s)
- P M Gallagher
- Neuropathology Department, Beaumont Hospital, Dublin, 9, Ireland
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32
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Folsom AR, Nieto FJ, McGovern PG, Tsai MY, Malinow MR, Eckfeldt JH, Hess DL, Davis CE. Prospective study of coronary heart disease incidence in relation to fasting total homocysteine, related genetic polymorphisms, and B vitamins: the Atherosclerosis Risk in Communities (ARIC) study. Circulation 1998; 98:204-10. [PMID: 9697819 DOI: 10.1161/01.cir.98.3.204] [Citation(s) in RCA: 401] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Elevated plasma total homocysteine (tHcy), low B-vitamin intake, and genetic polymorphisms related to tHcy metabolism may play roles in coronary heart disease (CHD). More prospective studies are needed. METHODS AND RESULTS We used a prospective case-cohort design to determine whether tHcy-related factors are associated with incidence of CHD over an average of 3.3 years of follow-up in a biracial sample of middle-aged men and women. Age-, race-, and field center-adjusted CHD incidence was associated positively (P<0.05) with tHcy in women but not men, and CHD was associated negatively (P<0.05) with plasma folate (women only), plasma pyridoxal 5'-phosphate (both sexes), and vitamin supplementation (women only). However, after accounting for other risk factors, only plasma pyridoxal 5'-phosphate was associated with CHD incidence; the relative risk for the highest versus lowest quintile of pyridoxal 5'-phosphate was 0.28 (95% CI=0.1 to 0.7). There was no association of CHD with the C677T mutation of the methylenetetrahydrofolate reductase gene or with 3 mutations of the cystathionine beta-synthase gene. CONCLUSIONS Our prospective findings add uncertainty to conclusions derived mostly from cross-sectional studies that tHcy is a major, independent, causative risk factor for CHD. Our findings point more strongly to the possibility that vitamin B6 offers independent protection. Randomized trials, some of which are under way, are needed to better clarify the interrelationships of tHcy, B vitamins, and cardiovascular disease.
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Affiliation(s)
- A R Folsom
- Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis 55454-1015, USA.
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33
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Abstract
An elevated level of total homocysteine (tHcy) in blood, denoted hyperhomocysteinemia, is emerging as a prevalent and strong risk factor for atherosclerotic vascular disease in the coronary, cerebral, and peripheral vessels, and for arterial and venous thromboembolism. The basis for these conclusions is data from about 80 clinical and epidemiological studies including more than 10,000 patients. Elevated tHcy confers a graded risk with no threshold, is independent of but may enhance the effect of the conventional risk factors, and seems to be a particularly strong predictor of cardiovascular mortality. Hyperhomocysteinemia is attributed to commonly occurring genetic and acquired factors including deficiencies of folate and vitamin B12. Supplementation with B-vitamins, in particular with folic acid, is an efficient, safe, and inexpensive means to reduce an elevated tHcy level. Studies are now in progress to establish whether such therapy will reduce cardiovascular risk.
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Affiliation(s)
- H Refsum
- Department of Pharmacology, University of Bergen, Norway.
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34
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Vilaseca MA, Moyano D, Artuch R, Ferrer I, Pineda M, Cardo E, Campistol J, Pavia C, Camacho JA. Selective Screening for Hyperhomocysteinemia in Pediatric Patients. Clin Chem 1998. [DOI: 10.1093/clinchem/44.3.662] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- M Antònia Vilaseca
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Dolores Moyano
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Rafael Artuch
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Imma Ferrer
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Mercè Pineda
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Esther Cardo
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Jaume Campistol
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - Carles Pavia
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
| | - José-Antonio Camacho
- Serv. de Bioquím., Neurol., i Pediatr., Hosp. Univ. Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950-Esplugues, Barcelona, Spain
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35
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Bostom AG, Gohh RY, Tsai MY, Hopkins-Garcia BJ, Nadeau MR, Bianchi LA, Jacques PF, Rosenberg IH, Selhub J. Excess prevalence of fasting and postmethionine-loading hyperhomocysteinemia in stable renal transplant recipients. Arterioscler Thromb Vasc Biol 1997; 17:1894-900. [PMID: 9351351 DOI: 10.1161/01.atv.17.10.1894] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hyperhomocysteinemia, either fasting or after methionine loading, may contribute to the increased incidence of cardiovascular disease events experienced by renal transplant recipients. Limited data are available on fasting homocysteine (Hcy) levels, and none on postmethionine-loading Hcy levels, in these patients. We assessed the prevalence and potential determinants of fasting and postmethionine-loading hyperhomocysteinemia in 29 stable renal transplant recipients and 58 age- and sex-matched, population-based controls free of renal disease with serum creatinine levels of 1.5 mg/dL or less. Total (t) plasma Hcy was determined fasting and 2 hours after methionine loading, along with fasting determinations of the B-vitamin cofactors/substrates for Hcy metabolism, ie, pyridoxal 5'-phosphate, B-12, and folate and serum creatinine. Geometric mean fasting (18.1 versus 9.8 microM, P < .001) and postmethionine-loading increase (22.0 versus 15.2, P = .001) in tHcy levels were significantly greater in the renal transplant recipients, as were the prevalence odds (with 95% confidence intervals) for fasting [14.8 (3.4-64.7)], postmethionine loading [6.9 (1.5-32.8)], combined fasting and postmethionine-loading [18.0 (2.3-142.1)] hyperhomocysteinemia, and inadequate circulating folate [4.2 (1.1-16.5)] or pyridoxal 5'-phosphate [3.2 (0.9-11.0) status. Correlation analyses suggested important potential relationships between creatinine and both fasting (+0.64, P < .001) and postmethionine-load increase (+0.38, P = .045) in tHcy, folate and fasting (-0.41, P = .025) tHcy, and pyridoxal 5'-phosphate and postmethionine-loading increase (-0.33, P = .091) in tHcy. We conclude that there is an excess prevalence of fasting and postmethionine-loading hyperhomocysteinemia in stable renal transplant recipients. Renal function is related to both fasting and postmethionine loading-hyperhomocysteinemia, inadequate folate status is associated with fasting hyperhomocysteinemia, and inadequate vitamin B-6 status may be related to postmethionine-loading hyperhomocysteinemia in this patient population.
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Affiliation(s)
- A G Bostom
- Jean Mayer USDA Human Nutrition Research Center, Tufts New England Medical Center, Boston, Mass., USA
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36
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Abstract
This review of recent advances covers (1) the metabolism of methionine and its regulation, emphasizing interactions with the three important vitamins folate, cobalamin and pyridoxine; (2) present knowledge of enzymological and moleculargenetic aspects of homozygous deficiencies of the three enzymes which cause elevated homocyst(e)ine; (3) recent clinical findings, post-methionine loading results related to enzyme and mutation studies in obligate heterozygotes for cystathionine beta-synthase deficiency; (4) important new evidence for disturbed homocysteine metabolism in neural tube defects, particularly based on studies of the thermolabile methylene-tetrahydrofolate reductase mutation which is also of importance in vascular disease; (5) the suitability and limitations of animal models that have so far been described.
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Affiliation(s)
- B Fowler
- University Children's Hospital, Basel, Switzerland
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Ramsbottom D, Scott JM, Molloy A, Weir DG, Kirke PN, Mills JL, Gallagher PM, Whitehead AS. Are common mutations of cystathionine beta-synthase involved in the aetiology of neural tube defects? Clin Genet 1997; 51:39-42. [PMID: 9084933 DOI: 10.1111/j.1399-0004.1997.tb02412.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mildly elevated maternal plasma homocysteine (Hcy) levels (hyperhomocysteinemia) have recently been observed in some neural tube defect (NTD) pregnancies. Plasma levels of Hcy are governed by both genetic and nutritional factors and the aetiology of NTDs is also known to have both genetic and nutritional components. We therefore examined the frequency of relatively common mutations in the enzyme cystathionine beta-synthase (CBS), which is one of the main enzymes that controls Hcy levels, in the NTD population. Neither the severely dysfunctional G307S CBS allele nor the recently reported 68 bp insertion/I278T CBS allele was observed at increased frequency in the cases relative to controls. We therefore conclude that loss of function CBS alleles do not account for a significant proportion of NTDs in Ireland.
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Affiliation(s)
- D Ramsbottom
- Department of Genetics, Trinity College, Dublin, Ireland
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