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Verónica B, Crespo C, Lochner N, Rossetti E, Tagliavini C, Bouso C, Eiroa H. New data supporting that early diagnosis and treatment are possible and necessary in intracellular cobalamin depletion: the case of transcobalamin II deficiency. J Pediatr Endocrinol Metab 2024; 37:380-386. [PMID: 38436354 DOI: 10.1515/jpem-2023-0577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 02/18/2024] [Indexed: 03/05/2024]
Abstract
OBJECTIVES Transcobalamin II (TC) promotes the cellular uptake of cobalamin (Cbl) through receptor-mediated endocytosis of the TC-cbl complex in peripheral tissues. TC deficiency is a rare disorder that causes intracellular Cbl depletion. It presents in early infancy with a failure to thrive, diarrhea, anemia, agammaglobulinemia, and pancytopenia. Data from five TC-deficient patients including clinical, biochemical, and molecular findings, as well as long-term outcomes, were collected. CASE PRESENTATION Mutation analysis revealed one unreported pathogenic variant in the TCN2 gene. One patient had exocrine pancreatic insufficiency. We conducted a retrospective analysis of C3 and C3/C2 from dried blood samples, as this is implemented for newborn screening (NBS). We detected a marked increase in the C3/C2 ratio in two samples. Treatment was based on parenteral Cbl. Three patients treated before six months of age had an initial favorable outcome, whereas the two treated later or inadequately had neurological impairment. CONCLUSIONS This is the first report of Argentinean patients with TC deficiency that detected a new variant in TCN2. NBS may be a tool for the early detection of TC deficiency. This data emphasizes that TC deficiency is a severe disorder that requires early detection and long-term, aggressive therapy. Accurate diagnosis is imperative, because early detection and treatment can be life-saving.
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Affiliation(s)
- Bindi Verónica
- Deparment of Inborn Error of Metabolism, 36947 Hospital de Pediatría Juan P. Garrahan , Buenos Aires, Argentina
| | - Carolina Crespo
- Department of Genetics, Molecular Biology Laboratory, 36947 Hospital de Pediatría Prof Dr Juan P Garrahan , Buenos Aires, Argentina
| | - Noelia Lochner
- Deparment of Inborn Error of Metabolism, 36947 Hospital de Pediatría Juan P. Garrahan , Buenos Aires, Argentina
| | - Estefanía Rossetti
- Department of Hematology, 36947 Hospital de Pediatría Juan P. Garrahan , Buenos Aires, Argentina
| | - Cecilia Tagliavini
- Inborn Errors of Metabolism Laboratory, 36947 Hospital de Pediatría Juan P. Garrahan , Buenos Aires, Argentina
| | - Carolina Bouso
- Department of Immunology, 36947 Hospital de Pediatría Juan P. Garrahan , Buenos Aires, Argentina
| | - Hernan Eiroa
- Deparment of Inborn Error of Metabolism, 36947 Hospital de Pediatría Juan P. Garrahan , Buenos Aires, Argentina
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2
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Oshi MAM, Alfaifi J, Alqahtani YAM, Aljabri MF, Kamal NM, Althopaity J, Althobaiti KA, Almalki AM, Abosabie SAS, Abosabie SA, Sherbiny HS, Almanjoomi SK, Abdallah EAA. "Progressive myoclonic ataxia and developmental/epileptic encephalopathy associated with a novel homozygous mutation in TCN2 gene". Mol Genet Genomic Med 2024; 12:e2282. [PMID: 37800653 PMCID: PMC10767415 DOI: 10.1002/mgg3.2282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 08/17/2023] [Accepted: 08/22/2023] [Indexed: 10/07/2023] Open
Abstract
BACKGROUND Transcobalamin II (TCN2) defect is a rare metabolic disorder associated with a range of neurological manifestations, including mild developmental delay, severe intellectual disability, ataxia, and, in some cases, seizures. Cobalamin, an essential nutrient, plays a crucial role in central nervous system myelination. CLINICAL PRESENTATION We present a family with an index patient who exhibited progressive neurodevelopmental regression starting at 9 months of age, accompanied by myoclonic seizures, ataxia, and tremor. No significant hematological abnormalities were observed. Exome sequencing analysis identified a novel homozygous mutation, c.3G>A - P(Met1I), affecting the acceptor site of intron 4 of the TCN2 gene (chromosome 22: 31003321, NM_000355.4), leading to likely pathogenic variant potentially affecting translation. Following treatment with hydroxocobalamin, the patient demonstrated partial clinical improvement. He has a sibling with overt hematological abnormalities and subtle neurological abnormalities who is homozygous to the same mutation. Both parents are heterozygous for the same mutation. CONCLUSIONS In infants presenting with unexplained non-specific neurological symptoms, irrespective of classical signs of vitamin B12 deficiency, evaluation for TCN2 defect should be considered. Early diagnosis and appropriate management can lead to favorable outcomes.
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Affiliation(s)
| | - Jaber Alfaifi
- Department of Child Health, College of MedicineUniversity of BishaBishaSaudi Arabia
| | - Youssef Ali M. Alqahtani
- Department of Child Health, College of MedicineKing Khalid UniversityAbhaKingdom of Saudi Arabia
| | | | - Naglaa M. Kamal
- Department of Pediatrics and Pediatric Hepatology, Kasr Alainy Faculty of MedicineCairo UniversityCairoEgypt
| | - Jwaher Althopaity
- Department of Medical GeneticsKing Fahad Medical CityRiyadhSaudi Arabia
| | | | | | - Salma A. S. Abosabie
- Faculty of MedicineJulius‐Maximilians‐Universität WürzburgWurzburgBavariaGermany
| | - Sara A. Abosabie
- Faculty of MedicineCharité Universitätsmedizin BerlinBerlinGermany
| | - Hanan Sakr Sherbiny
- Department of Child Health, College of MedicineUniversity of BishaBishaSaudi Arabia
- Department of pediatrics, Faculty of MedicineZagazig UniversityZagazigEgypt
| | | | - Enas A. A. Abdallah
- Department of Pediatrics and Pediatric Hepatology, Kasr Alainy Faculty of MedicineCairo UniversityCairoEgypt
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3
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Lim J, Hall R, Grist S, Ross DM. Identification of two novel transcobalamin 2 variants associated with developmental delay and megaloblastic anaemia in infancy. Pathology 2022; 54:958-959. [PMID: 35304013 DOI: 10.1016/j.pathol.2021.12.299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/03/2021] [Accepted: 12/12/2021] [Indexed: 12/14/2022]
Affiliation(s)
- Jonathan Lim
- Department of Haematology, Flinders Medical Centre, Bedford Park, SA, Australia; Haematology Directorate, SA Pathology, Adelaide, SA, Australia.
| | - Rachel Hall
- Genetic Pathology Directorate, SA Pathology, Adelaide, SA, Australia; College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
| | - Scott Grist
- Genetic Pathology Directorate, SA Pathology, Adelaide, SA, Australia; College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
| | - David M Ross
- Department of Haematology, Flinders Medical Centre, Bedford Park, SA, Australia; Haematology Directorate, SA Pathology, Adelaide, SA, Australia; College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
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4
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Mosca P, Robert A, Alberto JM, Meyer M, Kundu U, Hergalant S, Umoret R, Coelho D, Guéant JL, Leheup B, Dreumont N. Vitamin B 12 Deficiency Dysregulates m6A mRNA Methylation of Genes Involved in Neurological Functions. Mol Nutr Food Res 2021; 65:e2100206. [PMID: 34291881 DOI: 10.1002/mnfr.202100206] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/05/2021] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Vitamin B12 deficiency presents various neurological manifestations, such as cognitive dysfunction, mental retardation, or memory impairment. However, the involved molecular mechanisms remain to date unclear. Vitamin B12 is essential for synthesizing S-adenosyl methionine (SAM), the methyl group donor used for almost all transmethylation reactions. Here, we investigate the m6A methylation of mRNAs and their related gene expression in models of vitamin B12 deficiency. METHODS AND RESULTS This study observes two cellular models deficient in vitamin B12 and hippocampi of mice knock-out for the CD320 receptor. The decrease in SAM levels resulting from vitamin B12 deficiency is associated with m6 A reduced levels in mRNAs. This is also potentially mediated by the overexpression of the eraser FTO. We further investigate mRNA methylation of some genes involved in neurological functions targeted by the m6A reader YTH proteins. We notably observe a m6A hypermethylation of Prkca mRNA and a consistently increased expression of PKCα, a kinase involved in brain development and neuroplasticity, in the two cellular models. CONCLUSION Our data show that m6A methylation in mRNA could be one of the contributing mechanisms that underlie the neurological manifestations produced by vitamin B12 deficiency.
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Affiliation(s)
- Pauline Mosca
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
| | - Aurélie Robert
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
| | | | - Marie Meyer
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
| | - Urbi Kundu
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
| | | | - Rémy Umoret
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
| | - David Coelho
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
| | | | - Bruno Leheup
- Université de Lorraine, Inserm, NGERE, Nancy, F-54000, France
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Mendes CC, Zampieri BL, Arantes LMRB, Melendez ME, Biselli JM, Carvalho AL, Eberlin MN, Riccio MF, Vannucchi H, Carvalho VM, Goloni-Bertollo EM, Pavarino ÉC. One-carbon metabolism and global DNA methylation in mothers of individuals with Down syndrome. Hum Cell 2021; 34:1671-1681. [PMID: 34410622 DOI: 10.1007/s13577-021-00586-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 07/26/2021] [Indexed: 10/20/2022]
Abstract
Down syndrome (DS) is the most common chromosomal disorder, resulting from the failure of normal chromosome 21 segregation. Studies have suggested that impairments within the one-carbon metabolic pathway can be of relevance for the global genome instability observed in mothers of individuals with DS. Based on the association between global DNA hypomethylation, genome instability, and impairments within the one-carbon metabolic pathway, the present study aimed to identify possible predictors, within the one-carbon metabolism, of global DNA methylation, measured by methylation patterns of LINE-1 and Alu repetitive sequences, in mothers of individuals with DS and mothers of individuals without the syndrome. In addition, we investigated one-carbon genetic polymorphisms and metabolites as maternal predisposing factors for the occurrence of trisomy 21 in children. Eighty-three samples of mothers of children with DS with karyotypically confirmed free trisomy 21 (case group) and 84 of mothers who had at least one child without DS or any other aneuploidy were included in the study. Pyrosequencing assays were performed to access global methylation. The results showed that group affiliation (case or control), betaine-homocysteine methyltransferase (BHMT) G742A and transcobalamin 2 (TCN2) C776G polymorphisms, and folate concentration were identified as predictors of global Alu DNA methylation values. In addition, thymidylate synthase (TYMS) 28-bp repeats 2R/3R or 3R/3R genotypes are independent maternal predisposing factors for having a child with DS. This study adds evidence that supports the association of impairments in the one-carbon metabolism, global DNA methylation, and the possibility of having a child with DS.
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Affiliation(s)
- Cristiani Cortez Mendes
- Unidade de Pesquisa em Genética e Biologia Molecular-UPGEM, Departamento de Biologia Molecular, Faculdade de Medicina de São José do Rio Preto-FAMERP, São José do Rio Preto, São Paulo, Brazil
| | | | | | - Matias Eliseo Melendez
- Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos, São Paulo, Brazil
| | - Joice Matos Biselli
- Universidade Estadual Paulista Júlio de Mesquita Filho, Instituto de Biociências, Letras e Ciências Exatas de São José do Rio Preto, Departamento de Ciências Biológicas, São José do Rio Preto, São Paulo, Brazil
| | - André Lopes Carvalho
- Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos, São Paulo, Brazil
| | - Marcos Nogueira Eberlin
- Universidade Presbiteriana Mackenzie, Discovery-Mackenzie-Núcleo Mackenzie de Pesquisa, Núcleo Mackenzie de Pesquisas em Ciência, Fé e Sociedade, São Paulo, São Paulo, Brazil
| | | | - Hélio Vannucchi
- Laboratório de Nutrição, Departamento de Clínica Médica, Faculdade de Medicina de Ribeirão Preto-USP, Ribeirão Preto, São Paulo, Brazil
| | | | - Eny Maria Goloni-Bertollo
- Unidade de Pesquisa em Genética e Biologia Molecular-UPGEM, Departamento de Biologia Molecular, Faculdade de Medicina de São José do Rio Preto-FAMERP, São José do Rio Preto, São Paulo, Brazil
| | - Érika Cristina Pavarino
- Unidade de Pesquisa em Genética e Biologia Molecular-UPGEM, Departamento de Biologia Molecular, Faculdade de Medicina de São José do Rio Preto-FAMERP, São José do Rio Preto, São Paulo, Brazil.
- , Av. Brigadeiro Faria Lima, 5416, Vila São Pedro, São José do Rio Preto, São Paulo, 15090-000, Brazil.
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Boachie J, Adaikalakoteswari A, Goljan I, Samavat J, Cagampang FR, Saravanan P. Intracellular and Tissue Levels of Vitamin B12 in Hepatocytes Are Modulated by CD320 Receptor and TCN2 Transporter. Int J Mol Sci 2021; 22:3089. [PMID: 33803025 PMCID: PMC8002616 DOI: 10.3390/ijms22063089] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/10/2021] [Accepted: 03/14/2021] [Indexed: 11/17/2022] Open
Abstract
The liver mass constitutes hepatocytes expressing receptors for vitamin B12 (B12)-bound transporters in circulation. However, intrahepatic and circulating B12 interrelationship levels remain unclear. We assessed the intracellular B12 levels at various circulating B12 concentrations in human HepG2 cell-line and liver tissue levels of B12 in the C57BL/6 mouse model. In HepG2 cells treated with a range of B12 concentrations, the intracellular and circulatory B12 levels, transcript and protein levels of B12 receptor (CD320) and transporter (TCN2) were determined using immunoassays, qRT-PCR and Western blot, respectively. Similar assessments were done in plasma and liver tissue of C57BL/6 mice, previously fed a diet of either a high or low B12 (30.82 µg B12/kg and 7.49 µg B12/kg, respectively) for 8-10 weeks. The physiological B12 status (0.15-1 nM) resulted in increased levels of intracellular B12 in HepG2 cells compared to supraphysiological levels of B12 (>1 nM). Gene and protein expression of CD320 and TCN2 were also higher at physiological levels of B12. Progressively increasing extracellular B12 to supraphysiological levels led to relative decreased levels of intracellular B12, lower expression of gene and protein levels of CD320 and TCN2. Similar results were observed in liver tissue from mice fed on a low B12 diet verses high B12 diet. These findings suggest that unlike supraphysiological B12, physiological levels of B12 in the extracellular media or circulation accelerates active transport of B12, and expression of CD320 and TCN2, resulting in higher relative uptake of B12 in hepatocytes.
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Affiliation(s)
- Joseph Boachie
- Division of Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry CV2 2DX, UK; (J.B.); (J.S.)
| | - Antonysunil Adaikalakoteswari
- Division of Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry CV2 2DX, UK; (J.B.); (J.S.)
- Department of Biosciences, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
| | - Ilona Goljan
- Diabetes Centre, George Eliot Hospital NHS Trust College Street, Nuneaton CV10 7DJ, UK;
| | - Jinous Samavat
- Division of Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry CV2 2DX, UK; (J.B.); (J.S.)
| | - Felino R. Cagampang
- Institute of Developmental Sciences, University of Southampton, Faculty of Medicine, Southampton General Hospital, Southampton SO16 6YD, UK;
| | - Ponnusamy Saravanan
- Division of Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry CV2 2DX, UK; (J.B.); (J.S.)
- Diabetes Centre, George Eliot Hospital NHS Trust College Street, Nuneaton CV10 7DJ, UK;
- Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry CV2 2DX, UK
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7
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Benoit CR, Stanton AE, Tartanian AC, Motzer AR, McGaughey DM, Bond SR, Brody LC. Functional and phylogenetic characterization of noncanonical vitamin B 12-binding proteins in zebrafish suggests involvement in cobalamin transport. J Biol Chem 2018; 293:17606-17621. [PMID: 30237171 PMCID: PMC6231144 DOI: 10.1074/jbc.ra118.005323] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/13/2018] [Indexed: 12/19/2022] Open
Abstract
In humans, transport of food-derived cobalamin (vitamin B12) from the digestive system into the bloodstream involves three paralogous proteins: transcobalamin (TC), haptocorrin (HC), and intrinsic factor (IF). Each of these proteins contains two domains, an α-domain and a β-domain, which together form a cleft in which cobalamin binds. Zebrafish (Danio rerio) are thought to possess only a single cobalamin transport protein, referred to as Tcn2, which is a transcobalamin homolog. Here, we used CRISPR/Cas9 mutagenesis to create null alleles of tcn2 in zebrafish. Fish homozygous for tcn2-null alleles were viable and exhibited no obvious developmentally or behaviorally abnormal phenotypes. For this reason, we hypothesized that previously unidentified cobalamin-carrier proteins encoded in the zebrafish genome may provide an additional pathway for cobalamin transport. We identified genes predicted to code for two such proteins, Tcn-beta-a (Tcnba) and Tcn-beta-b (Tcnbb), which differ from all previously characterized cobalamin transport proteins as they lack the α-domain. These β-domain-only proteins are representative of an undescribed class of cobalamin-carrier proteins that are highly conserved throughout the ray-finned fishes. We observed that the genes encoding the three cobalamin transport homologs, tcn2, tcnba, and tcnbb, are expressed in unique spatial and temporal patterns in the developing zebrafish. Moreover, exogenously expressed recombinant Tcnba and Tcnbb bound cobalamin with high affinity, comparable with binding by full-length Tcn2. Taken together, our results suggest that this noncanonical protein structure has evolved to fully function as a cobalamin-carrier protein, thereby allowing for a compensatory cobalamin transport mechanism in the tcn2-/- zebrafish.
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Affiliation(s)
- Courtney R Benoit
- From the Gene and Environment Interaction Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892 and
| | - Abigail E Stanton
- From the Gene and Environment Interaction Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892 and
| | - Aileen C Tartanian
- From the Gene and Environment Interaction Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892 and
| | - Andrew R Motzer
- From the Gene and Environment Interaction Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892 and
| | - David M McGaughey
- From the Gene and Environment Interaction Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892 and
| | - Stephen R Bond
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Lawrence C Brody
- From the Gene and Environment Interaction Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892 and
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8
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Hu Y, Raffield LM, Polfus LM, Moscati A, Nadkarni G, Preuss MH, Zhong X, Wei Q, Rich SS, Li Y, Wilson JG, Correa A, Loos RJF, Li B, Auer PL, Reiner AP. A common TCN1 loss-of-function variant is associated with lower vitamin B 12 concentration in African Americans. Blood 2018; 131:2859-2863. [PMID: 29764838 PMCID: PMC6014360 DOI: 10.1182/blood-2018-03-841023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- Yao Hu
- Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA
| | - Laura M Raffield
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Linda M Polfus
- Center for Genetic Epidemiology, Department of Preventative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Arden Moscati
- Charles Bronfman Institute for Personalized Medicine and
| | - Girish Nadkarni
- Department of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Xue Zhong
- Vanderbilt Genetics Institute, Nashville, TN
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Qiang Wei
- Vanderbilt Genetics Institute, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Stephen S Rich
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA
| | - Yun Li
- Department of Genetics
- Department of Biostatistics, and
- Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | | | - Adolfo Correa
- Department of Pediatrics and Medicine, University of Mississippi Medical Center, Jackson, MS
| | - Ruth J F Loos
- Charles Bronfman Institute for Personalized Medicine and
- Genetics of Obesity and Related Metabolic Traits Program and
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Bingshan Li
- Vanderbilt Genetics Institute, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Paul L Auer
- Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI; and
| | - Alex P Reiner
- Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA
- Department of Epidemiology, University of Washington, Seattle, WA
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Velkova A, Diaz JEL, Pangilinan F, Molloy AM, Mills JL, Shane B, Sanchez E, Cunningham C, McNulty H, Cropp CD, Bailey-Wilson JE, Wilson AF, Brody LC. The FUT2 secretor variant p.Trp154Ter influences serum vitamin B12 concentration via holo-haptocorrin, but not holo-transcobalamin, and is associated with haptocorrin glycosylation. Hum Mol Genet 2017; 26:4975-4988. [PMID: 29040465 PMCID: PMC5886113 DOI: 10.1093/hmg/ddx369] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 11/14/2022] Open
Abstract
Vitamin B12 deficiency is common in older individuals. Circulating vitamin B12 concentration can be used to diagnose deficiency, but this test has substantial false positive and false negative rates. We conducted genome-wide association studies (GWAS) in which we resolved total serum vitamin B12 into the fractions bound to transcobalamin and haptocorrin: two carrier proteins with very different biological properties. We replicated reported associations between total circulating vitamin B12 concentrations and a common null variant in FUT2. This allele determines the secretor phenotype in which blood group antigens are found in non-blood body fluids. Vitamin B12 bound to haptocorrin (holoHC) remained highly associated with FUT2 rs601338 (p.Trp154Ter). Transcobalamin bound vitamin B12 (holoTC) was not influenced by this variant. HoloTC is the bioactive the form of the vitamin and is taken up by all tissues. In contrast, holoHC is only taken up by the liver. Using holoHC from individuals with known FUT2 genotypes, we demonstrated that FUT2 rs601338 genotype influences the glycosylation of haptocorrin. We then developed an experimental model demonstrating that holoHC is transported into cultured hepatic cells (HepG2) via the asialoglycoprotein receptor (ASGR). Our data challenge current published hypotheses on the influence of genetic variation on this clinically important measure and are consistent with a model in which FUT2 rs601338 influences holoHC by altering haptocorrin glycosylation, whereas B12 bound to non-glycosylated transcobalamin (i.e. holoTC) is not affected. Our findings explain some of the observed disparity between use of total B12 or holoTC as first-line clinical tests of vitamin B12 status.
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Affiliation(s)
- Aneliya Velkova
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - Jennifer E L Diaz
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - Faith Pangilinan
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - Anne M Molloy
- Department of Clinical Medicine, School of Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - James L Mills
- Division of Intramural Population Health Research, Eunice Kennedy Shriver NICHD, Bethesda, MD 20852, USA
| | - Barry Shane
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA
| | - Erica Sanchez
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | | | - Helene McNulty
- Northern Ireland Centre for Food and Health, University of Ulster, Coleraine BT52 1SA, Northern Ireland
| | - Cheryl D Cropp
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, Bethesda, MD 21224, USA
| | - Joan E Bailey-Wilson
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, Bethesda, MD 21224, USA
| | - Alexander F Wilson
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, Bethesda, MD 21224, USA
| | - Lawrence C Brody
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA
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10
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Hebbar P, Alkayal F, Nizam R, Melhem M, Elkum N, John SE, Abufarha M, Alsmadi O, Thanaraj TA. The TCN2 variant of rs9606756 [Ile23Val] acts as risk loci for obesity-related traits and mediates by interacting with Apo-A1. Obesity (Silver Spring) 2017; 25:1098-1108. [PMID: 28417558 DOI: 10.1002/oby.21826] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 02/02/2017] [Accepted: 02/22/2017] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Despite alarming obesity levels in the Arabian Peninsula, its population lacks convincingly identified genetic determinants of obesity. A genome-wide association study was performed for obesity-related anthropometric traits in Arabs and to decipher mechanisms by which the variants mediate traits. METHODS The Illumina HumanOmniExpress BeadChip was used to genotype 1,353 Arab individuals (largely with Class I obesity) from Kuwait. Genome-wide association tests for obesity-related anthropometric traits were performed. Top associations were tested for replication in an independent cohort (1,176 unrelated Arabs). Resultant variants were investigated for interactions with obesity-related plasma biomarkers. Pathway analysis was performed on genes harboring markers in linkage disequilibrium (LD) with identified variants. RESULTS The rs9606756[c.67A>G,p.Ile23Val] variant from TCN2 was associated with waist circumference (WC) at nearly genome-wide significance (P = 8.92E-08). WC was inversely related with Apo-A1 or high-density lipoprotein levels; individuals with the AG genotype exhibited stronger relationship than those with the reference AA genotype. Interaction involving the AG genotype (effect allele = G) significantly contributed to an increase in anthropometric traits (particularly WC). Genes harboring single-nucleotide polymorphisms in LD with rs9606756 mapped onto an interaction network (with TP53 as central element) of established obesity/diabetes-related protein components. CONCLUSIONS The TCN2 variant acts as a risk factor for WC in the Arab population. The variant mediates obesity-related anthropometric traits via interactions with Apo-A1/high-density lipoprotein or TP53.
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Affiliation(s)
| | | | | | | | - Naser Elkum
- Sidra Medical and Research Center, Research Department Doha, Qatar
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11
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Keller P, Rufener J, Schild C, Fedosov SN, Nissen PH, Nexo E. False low holotranscobalamin levels in a patient with a novel TCN2 mutation. Clin Chem Lab Med 2017; 54:1739-1743. [PMID: 27155006 DOI: 10.1515/cclm-2016-0063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 03/14/2016] [Indexed: 01/03/2023]
Abstract
BACKGROUND Measurement of holotranscobalamin (holoTC) is increasingly used as a screening test for cobalamin (Cbl) deficiency. A level well below the reference interval strongly supports a deficient state. We examined a 21-year-old woman diagnosed as Cbl deficient because of an extremely low holoTC level as measured by the Abbott Architect Assay. METHODS The patient was evaluated for Cbl deficiency employing an in-house holoTC method as well as other routine markers of Cbl status. Further analyses included exploration of the Cbl binding proteins employing gel filtration of a serum sample saturated with 57 Co-labeled Cbl and Sanger sequencing of exons 1-9 and the intron-exon boundaries of the TCN2 gene, the gene coding for transcobalamin (TC). RESULTS The patient had normal hematological variables throughout. Despite initial treatment with Cbl, holoTC as measured by the Abbott assay remained low, while holoTC measured with the in-house assay was normal, and behaved as TC upon gel-filtration. By Sanger sequencing, we detected a homozygous single point mutation c.855T>A in exon 6 of TCN2, corresponding to a asparagine (Asn) to lysine (Lys) substitution in position 267 of the mature protein. CONCLUSIONS We describe a novel point mutation of the TCN2 gene. The mutation does not seem to interfere with the function of TC, but the mutation may well explain the low level of holoTC detected by the Abbott assay. Our results underscores that mutations of TCN2 have to be considered when implausible holoTC results are obtained.
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12
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Zhao L, Wei Y, Song A, Li Y. Association study between genome-wide significant variants of vitamin B12 metabolism and gastric cancer in a han Chinese population. IUBMB Life 2016; 68:303-10. [PMID: 26959381 DOI: 10.1002/iub.1485] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 01/21/2016] [Accepted: 01/24/2016] [Indexed: 11/06/2022]
Abstract
Gastric cancer is one of the leading causes of cancer mortality worldwide. Accumulating evidence suggests that vitamin B12 plays an important role in the development of gastric cancer. Genome-wide association studies on metabolites in the one-carbon metabolism pathway identified several vitamin B12-related polymorphisms. Therefore, we investigated the association between variants within vitamin B12-related genes and gastric cancer in a Han Chinese population. Eight variants within the genome were significant vitamin B12-related genes, and they were selected for analysis in this case-control study. This study used a total of 492 gastric cancer patients and 550 noncancer controls. The variant rs526934 from the TCN1 gene was associated with an increased risk of developing gastric cancer. Increased risks of gastric cancer occurrence were observed in the minor G allele (OR = 1.25, 95% CI = 1.03-1.52, P = 0.031) and GG genotype (OR = 2.06, 95% CI = 1.24-3.42, P = 0.0043) compared with the wild-type A allele and AA-GA genotype, respectively. In the haplotypic analysis, we found that the CUBN haplotypes were associated with an altered gastric cancer risk. The rs1801222T/rs11254363A (OR = 1.40, 95% CI = 1.05-1.86, P = 0.021) and rs1801222C/rs11254363G (OR = 4.39, 95% CI = 2.32-8.30, P < 0.0001) haplotypes exhibited an increased gastric cancer risk, while rs1801222T/rs11254363G showed protective effects against gastric cancer (OR = 0.43, 95% CI = 0.25-0.73, P = 0.002) compared with the wild-type rs1801222C/rs11254363A haplotype. The circulating vitamin B12 concentration-related variants were associated with the occurrence of gastric cancer. This finding shed light on the unexpected role of vitamin B12 metabolism genes in gastric carcinogenesis and highlighted the interplay of diet, genetics, and human cancers.
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Affiliation(s)
- Lei Zhao
- The Second Hospital of Lanzhou University, Lanzhou, Gansu, People's Republic of China
- Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou, Gansu, People's Republic of China
| | - Yucai Wei
- The Second Hospital of Lanzhou University, Lanzhou, Gansu, People's Republic of China
- Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou, Gansu, People's Republic of China
| | - Ailing Song
- The Second Hospital of Lanzhou University, Lanzhou, Gansu, People's Republic of China
- Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou, Gansu, People's Republic of China
| | - Yumin Li
- The Second Hospital of Lanzhou University, Lanzhou, Gansu, People's Republic of China
- Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou, Gansu, People's Republic of China
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Bartakke S, Saindane A, Udgirkar V, Shrividya S, Bhavani GS, Girisha KM. Novel Mutation in an Indian Patient with Transcobalamin II Deficiency. Indian J Pediatr 2015; 82:1073-4. [PMID: 25947267 DOI: 10.1007/s12098-015-1770-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/09/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Sandip Bartakke
- Department of Clinical Hematology, Aditya Birla Memorial Hospital, Chinchwad, Pune, 411033, India.
| | - Avinash Saindane
- Department of Pediatrics, Aditya Birla Memorial Hospital, Chinchwad, Pune, India
| | | | - S Shrividya
- Department of Pathology, Aditya Birla Memorial Hospital, Chinchwad, Pune, India
| | | | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal, India
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14
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Fiorito G, Guarrera S, Valle C, Ricceri F, Russo A, Grioni S, Mattiello A, Di Gaetano C, Rosa F, Modica F, Iacoviello L, Frasca G, Tumino R, Krogh V, Panico S, Vineis P, Sacerdote C, Matullo G. B-vitamins intake, DNA-methylation of One Carbon Metabolism and homocysteine pathway genes and myocardial infarction risk: the EPICOR study. Nutr Metab Cardiovasc Dis 2014; 24:483-488. [PMID: 24418380 DOI: 10.1016/j.numecd.2013.10.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND AIMS Several epidemiological studies highlighted the association between folate and B-vitamins low intake and cardiovascular diseases (CVD) risk. Contrasting results were reported on the relationship between folate intake and DNA-methylation. Folate and B-vitamins may modulate DNA-methylation of specific enzymes which are included in the One-Carbon Metabolism (OCM) and in the homocysteine (Hcy) pathways. The aim of the study was to evaluate whether DNA-methylation profiles of OCM and Hcy genes could modulate the myocardial infarction (MI) risk conferred by a low B-vitamins intake. METHODS AND RESULTS Study sample (206 MI cases and 206 matched controls) is a case-control study nested in the prospective EPIC cohort. Methylation levels of 33 candidate genes where extracted by the whole epigenome analysis (Illumina-HumanMethylation450K-BeadChip). We identified three differentially methylated regions in males (TCN2 promoter, CBS 5'UTR, AMT gene-body) and two in females (PON1 gene-body, CBS 5'UTR), each of them characterized by an increased methylation in cases. Functional in silico analysis suggested a decreased expression in cases. A Recursively Partitioned Mixture Model cluster algorithm identified distinct methylation profiles associated to different MI risk: high-risk vs. low-risk methylation profile groups, OR = 3.49, p = 1.87 × 10(-)(4) and OR = 3.94, p = 0.0317 in males and females respectively (multivariate logistic regression adjusted for classical CVD risk factors). Moreover, a general inverse relationship between B-vitamins intake and DNA-methylation of the candidate genes was observed. CONCLUSIONS Our findings support the hypothesis that DNA-methylation patterns in specific regions of OCM and Hcy pathways genes may modulate the CVD risk conferred by folate and B-vitamins low intake.
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Affiliation(s)
- G Fiorito
- Human Genetics Foundation, Torino, Italy; Department of Medical Sciences, University of Torino, Italy
| | - S Guarrera
- Human Genetics Foundation, Torino, Italy
| | - C Valle
- Human Genetics Foundation, Torino, Italy
| | - F Ricceri
- Human Genetics Foundation, Torino, Italy; Department of Medical Sciences, University of Torino, Italy
| | - A Russo
- Human Genetics Foundation, Torino, Italy; Department of Medical Sciences, University of Torino, Italy
| | - S Grioni
- Department of Preventive and Predictive Medicine, Epidemiology and Prevention Unit, Fondazione IRCSS Istituto Nazionale dei Tumori, Milano, Italy
| | - A Mattiello
- Department of Clinical and Experimental Medicine, Federico II University, Napoli, Italy
| | - C Di Gaetano
- Human Genetics Foundation, Torino, Italy; Department of Medical Sciences, University of Torino, Italy
| | - F Rosa
- Human Genetics Foundation, Torino, Italy
| | - F Modica
- Human Genetics Foundation, Torino, Italy
| | - L Iacoviello
- Department of Epidemiology and Prevention, IRCCS Istituto Neurologico Mediterraneo Neuromed, Italy
| | - G Frasca
- Cancer Registry and Histopathology Unit, "Civile-M.P. Arezzo" Hospital, Ragusa, Italy
| | - R Tumino
- Cancer Registry and Histopathology Unit, "Civile-M.P. Arezzo" Hospital, Ragusa, Italy
| | - V Krogh
- Department of Preventive and Predictive Medicine, Epidemiology and Prevention Unit, Fondazione IRCSS Istituto Nazionale dei Tumori, Milano, Italy
| | - S Panico
- Department of Clinical and Experimental Medicine, Federico II University, Napoli, Italy
| | - P Vineis
- Human Genetics Foundation, Torino, Italy; Epidemiology and Public Health, Imperial College London, UK
| | - C Sacerdote
- Human Genetics Foundation, Torino, Italy; Cancer Epidemiology, CPO-Piemonte, Torino, Italy
| | - G Matullo
- Human Genetics Foundation, Torino, Italy; Department of Medical Sciences, University of Torino, Italy.
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15
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Irizar H, Muñoz-Culla M, Sepúlveda L, Sáenz-Cuesta M, Prada Á, Castillo-Triviño T, Zamora-López G, de Munain AL, Olascoaga J, Otaegui D. Transcriptomic profile reveals gender-specific molecular mechanisms driving multiple sclerosis progression. PLoS One 2014; 9:e90482. [PMID: 24587374 PMCID: PMC3938749 DOI: 10.1371/journal.pone.0090482] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 01/31/2014] [Indexed: 12/21/2022] Open
Abstract
Background Although the most common clinical presentation of multiple sclerosis (MS) is the so called Relapsing-Remitting MS (RRMS), the molecular mechanisms responsible for its progression are currently unknown. To tackle this problem, a whole-genome gene expression analysis has been performed on RRMS patients. Results The comparative analysis of the Affymetrix Human Gene 1.0 ST microarray data from peripheral blood leucocytes obtained from 25 patients in remission and relapse and 25 healthy subjects has revealed 174 genes altered in both remission and relapse, a high proportion of them showing what we have called “mirror pattern”: they are upregulated in remission and downregulated in relapse or vice versa. The coexpression analysis of these genes has shown that they are organized in three female-specific and one male-specific modules. Conclusions The interpretation of the modules of the coexpression network suggests that Epstein-Barr virus (EBV) reactivation of B cells happens in MS relapses; however, qPCR expression data of the viral genes supports that hypothesis only in female patients, reinforcing the notion that different molecular processes drive disease progression in females and males. Besides, we propose that the “primed” state showed by neutrophils in women is an endogenous control mechanism triggered to keep EBV reactivation under control through vitamin B12 physiology. Finally, our results also point towards an important sex-specific role of non-coding RNA in MS.
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Affiliation(s)
- Haritz Irizar
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
| | - Maider Muñoz-Culla
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
| | - Lucia Sepúlveda
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
| | - Matías Sáenz-Cuesta
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
| | - Álvaro Prada
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
- Hospital Universitario Donostia, Immunology Department, Donostia-San Sebastian, Spain
| | - Tamara Castillo-Triviño
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
| | - Gorka Zamora-López
- Bernstein Center for Computational Neuroscience, Humboldt-Universität zu Berlin, Berlin, Germany
- Center for Brain and Cognition, Universistat Pompeu Fabra, Barcelona, Spain
| | - Adolfo López de Munain
- Hospital Universitario Donostia, Neurology Department, Donostia-San Sebastian, Spain
- Centro de Investigaciones Biomédicas en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Carlos III, Ministerio de Ciencia e Innovación, Madrid, Spain
| | - Javier Olascoaga
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
- Hospital Universitario Donostia, Neurology Department, Donostia-San Sebastian, Spain
| | - David Otaegui
- Multiple Sclerosis Unit, Neuroscience Area, Biodonostia Health Research Institute, Donostia-San Sebastian, Spain
- Spanish Multiple Sclerosis Net (REEM), Barcelona, Spain
- * E-mail:
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Unal S, Tezol O, Oztas Y. A novel mutation of the transcobalamin II gene in an infant presenting with hemophagocytic lymphohistiocytosis. Int J Hematol 2014; 99:659-62. [PMID: 24563082 DOI: 10.1007/s12185-014-1545-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/03/2014] [Accepted: 02/12/2014] [Indexed: 11/25/2022]
Abstract
Transcobalamin II (TC II) deficiency is a rare disorder of cobalamin (CBL, vitamin B12) metabolism that occurs due to mutations in transcobalamin gene (TCN2). Hemophagocytic lymphohistiocytosis (HLH) in contrast is a syndrome characterized by uncontrolled immune response with hyperinflammation. A 2-month-old male baby was admitted with complaints of fever, cough, diarrhea, and respiratory distress. The parents were first cousins. The baby exhibited five of the eight diagnostic criteria for HLH-2004 and was diagnosed as HLH. A second bone marrow aspiration demonstrated megaloblastic changes in the erythroid series. The patient's vitamin B12 level was normal; however, hyperhomocysteinemia was present. A genetic deficiency of TC II was suspected. The patient and his parents were tested for TCN2 mutation. He had a homozygote mutation that was not included in Human 'Gene Mutation Database Cardiff'. The patient was treated with intramuscular vitamin B12, which was followed by improvement in both clinical and laboratory findings. He was 12 months old at the time of this report, with normal physical and neuromotor development. In this case presenting with the clinical and laboratory findings of HLH, TC II deficiency was diagnosed. A new mutation was found that was not reported before. Potential causative mechanisms of HLH induced by defects of cobalamin synthesis merit further investigation.
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Affiliation(s)
- Selma Unal
- Hematology Unit, Department of Pediatrics, Faculty of Medicine, Mersin University, Mersin, Turkey,
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17
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Wang J, Zhao JY, Wang F, Peng QQ, Hou J, Sun SN, Gui YH, Duan WY, Qiao B, Wang HY. A genetic variant in vitamin B12 metabolic genes that reduces the risk of congenital heart disease in Han Chinese populations. PLoS One 2014; 9:e88332. [PMID: 24533076 PMCID: PMC3922769 DOI: 10.1371/journal.pone.0088332] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 01/06/2014] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Genome-wide association studies on components of the one-carbon metabolic pathway revealed that human vitamin B12 levels could be significantly influenced by variations in the fucosyltransferase 2 (FUT2), cubilin (CUBN), and transcobalamin-I (TCN1) genes. An altered vitamin B12 level is an important factor that disturbs the homeostasis of the folate metabolism pathway, which in turn can potentially lead to the development of congenital heart disease (CHD). Therefore, we investigated the association between the variants of vitamin B12-related genes and CHD in Han Chinese populations. METHODS AND RESULTS Six variants of the vitamin B12-related genes were selected for analysis in two independent case-control studies, with a total of 868 CHD patients and 931 controls. The variant rs11254363 of the CUBN gene was associated with a decreased risk of developing CHD in both the separate and combined case-control studies. Combined samples from the two cohorts had a significant decrease in CHD risk for the G allele (OR = 0.48, P = 1.7×10⁻⁵) and AG+GG genotypes (OR = 0.49, P = 4×10⁻⁵), compared with the wild-type A allele and AA genotype, respectively. CONCLUSIONS Considering the G allele of variant rs11254363 of the CUBN gene was associated with an increased level of circulating vitamin B12. This result suggested that the carriers of the G allele would benefit from the protection offered by the high vitamin B12 concentration during critical heart development stages. This finding shed light on the unexpected role of CUBN in CHD development and highlighted the interplay of diet, genetics, and human birth defects.
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Affiliation(s)
- Jue Wang
- The State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, China
| | - Jian-Yuan Zhao
- The State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, China
| | - Feng Wang
- Children’s Hospital Shanghai, Fudan University, Shanghai, China
| | - Qian-Qian Peng
- CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jia Hou
- Children’s Hospital Shanghai, Fudan University, Shanghai, China
| | - Shu-Na Sun
- Children’s Hospital Shanghai, Fudan University, Shanghai, China
| | - Yong-Hao Gui
- Children’s Hospital Shanghai, Fudan University, Shanghai, China
| | - Wen-Yuan Duan
- Institute of Cardiovascular Disease General Hospital of Jinan Military Region, Jinan, China
| | - Bin Qiao
- Institute of Cardiovascular Disease General Hospital of Jinan Military Region, Jinan, China
| | - Hong-Yan Wang
- The State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, China
- Children’s Hospital Shanghai, Fudan University, Shanghai, China
- The Institutes of Biomedical Sciences, Fudan University, Shanghai, China
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Furger E, Frei DC, Schibli R, Fischer E, Prota AE. Structural basis for universal corrinoid recognition by the cobalamin transport protein haptocorrin. J Biol Chem 2013; 288:25466-25476. [PMID: 23846701 PMCID: PMC3757208 DOI: 10.1074/jbc.m113.483271] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/08/2013] [Indexed: 12/25/2022] Open
Abstract
Cobalamin (Cbl; vitamin B12) is an essential micronutrient synthesized only by bacteria. Mammals have developed a sophisticated uptake system to capture the vitamin from the diet. Cbl transport is mediated by three transport proteins: transcobalamin, intrinsic factor, and haptocorrin (HC). All three proteins have a similar overall structure but a different selectivity for corrinoids. Here, we present the crystal structures of human HC in complex with cyanocobalamin and cobinamide at 2.35 and 3.0 Å resolution, respectively. The structures reveal that many of the interactions with the corrin ring are conserved among the human Cbl transporters. However, the non-conserved residues Asn-120, Arg-357, and Asn-373 form distinct interactions allowing for stabilization of corrinoids other than Cbl. A central binding motif forms interactions with the e- and f-side chains of the corrin ring and is conserved in corrinoid-binding proteins of other species. In addition, the α- and β-domains of HC form several unique interdomain contacts and have a higher shape complementarity than those of intrinsic factor and transcobalamin. The stabilization of ligands by all of these interactions is reflected in higher melting temperatures of the protein-ligand complexes. Our structural analysis offers fundamental insights into the unique binding behavior of HC and completes the picture of Cbl interaction with its three transport proteins.
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Affiliation(s)
| | - Dominik C Frei
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI and
| | - Roger Schibli
- From the Center for Radiopharmaceutical Sciences and; the Institute of Pharmaceutical Sciences, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8093 Zürich, Switzerland
| | | | - Andrea E Prota
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI and.
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Sjuts H, Dunstan MS, Fisher K, Leys D. Structure of the cobalamin-binding protein of a putative O-demethylase from Desulfitobacterium hafniense DCB-2. Acta Crystallogr D Biol Crystallogr 2013; 69:1609-16. [PMID: 23897483 PMCID: PMC3727330 DOI: 10.1107/s0907444913011323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 04/25/2013] [Indexed: 11/10/2022]
Abstract
This study describes the identification and the structural and spectroscopic analysis of a cobalamin-binding protein (termed CobDH) implicated in O-demethylation by the organohalide-respiring bacterium Desulfitobacterium hafniense DCB-2. The 1.5 Å resolution crystal structure of CobDH is presented in the cobalamin-bound state and reveals that the protein is composed of an N-terminal helix-bundle domain and a C-terminal Rossmann-fold domain, with the cobalamin coordinated in the base-off/His-on conformation similar to other cobalamin-binding domains that catalyse methyl-transfer reactions. EPR spectroscopy of CobDH confirms cobalamin binding and reveals the presence of a cob(III)alamin superoxide, indicating binding of oxygen to the fully oxidized cofactor. These data provide the first structural insights into the methyltransferase reactions that occur during O-demethylation by D. hafniense.
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Affiliation(s)
- Hanno Sjuts
- Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, England
| | - Mark S. Dunstan
- Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, England
| | - Karl Fisher
- Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, England
| | - David Leys
- Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, England
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Furger E, Fedosov SN, Launholt Lildballe D, Waibel R, Schibli R, Nexo E, Fischer E. Comparison of recombinant human haptocorrin expressed in human embryonic kidney cells and native haptocorrin. PLoS One 2012; 7:e37421. [PMID: 22662153 PMCID: PMC3360681 DOI: 10.1371/journal.pone.0037421] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/20/2012] [Indexed: 02/02/2023] Open
Abstract
Haptocorrin (HC) is a circulating corrinoid binding protein with unclear function. In contrast to transcobalamin, the other transport protein in blood, HC is heavily glycosylated and binds a variety of cobalamin (Cbl) analogues. HC is present not only in blood but also in various secretions like milk, tears and saliva. No recombinant form of HC has been described so far. We report the expression of recombinant human HC (rhHC) in human embryonic kidney cells. We purified the protein with a yield of 6 mg (90 nmol) per litre of cell culture supernatant. The isolated rhHC behaved as native HC concerning its spectral properties and ability to recognize both Cbl and its baseless analogue cobinamide. Similar to native HC isolated from blood, rhHC bound to the asialoglycoprotein receptor only after removal of terminal sialic acid residues by treatment with neuraminidase. Interestingly, rhHC, that compared to native HC contains four excessive amino acids (…LVPR) at the C-terminus, showed subtle changes in the binding kinetics of Cbl, cobinamide and the fluorescent Cbl conjugate CBC. The recombinant protein has properties very similar to native HC and although showing slightly different ligand binding kinetics, rhHC is valuable for further biochemical and structural studies.
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Affiliation(s)
- Evelyne Furger
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland
| | | | | | - Robert Waibel
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland
| | - Ebba Nexo
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
| | - Eliane Fischer
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland
- * E-mail:
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Nissen PH, Nordwall M, Hoffmann-Lücke E, Sorensen BS, Nexo E. Transcobalamin deficiency caused by compound heterozygosity for two novel mutations in the TCN2 gene: a study of two affected siblings, their brother, and their parents. J Inherit Metab Dis 2010; 33 Suppl 3:S269-74. [PMID: 20607612 DOI: 10.1007/s10545-010-9145-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 05/19/2010] [Accepted: 06/01/2010] [Indexed: 11/28/2022]
Abstract
Transcobalamin (TC) deficiency (OMIM# 275350) is a rare, autosomal recessive disorder that presents in early infancy with a broad spectrum of symptoms, including failure to thrive, megaloblastic anemia, immunological deficiency, and neurological symptoms. Here we report a study of a family (parents and three children) with two children suffering from TC deficiency caused by two different mutations in the TCN2 gene. Initially, molecular genetic analysis of genomic DNA revealed a heterozygous mutation in the +1 position of exon 7 (c.1106+1 G > A) in the father and all three children. Bioinformatic analysis indicates that this mutation causes exon skipping, and further experiments supported this hypothesis and suggested that the mutant allele undergoes nonsense-mediated messenger RNA (mRNA) decay. We did not identify further mutations in genomic DNA that could explain TC deficiency in the two children. However, further efforts using complementary DNA (cDNA) derived from RNA from blood leukocytes identified a large deletion removing the entire exon 8, resulting in a frameshift and a premature stop codon (p.E371fsX372) in the mother and the two affected children. Our data indicate that if exon-by-exon DNA sequencing of genomic DNA does not uncover mutations corresponding to the phenotype, a systematic search for other mutations should be initiated by sequencing cDNA or using semiquantitative methods to detect large deletions in TCN2.
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Affiliation(s)
- Peter H Nissen
- Department of Clinical Biochemistry, AS, Aarhus University Hospital, Norrebrogade 44, DK 8000 Aarhus C, Denmark
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Carmel R, Bellevue R, Kelman Z. Low cobalamin levels associated with sickle cell disease: Contrasting origins and clinical meanings in two instructive patients. Am J Hematol 2010; 85:436-9. [PMID: 20309855 DOI: 10.1002/ajh.21678] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Ralph Carmel
- Department of Medicine, New York Methodist Hospital, Brooklyn, 11215, USA.
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Matteini AM, Walston JD, Bandeen-Roche K, Arking DE, Allen RH, Fried LP, Chakravarti A, Stabler SP, Fallin MD. Transcobalamin-II variants, decreased vitamin B12 availability and increased risk of frailty. J Nutr Health Aging 2010; 14:73-7. [PMID: 20082058 PMCID: PMC3042247 DOI: 10.1007/s12603-010-0013-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE This project was designed to follow-up prior evidence that demonstrated a significant association between vitamin B12 transport and metabolism and the frailty syndrome in community-dwelling older women. The cross-sectional relationship between genetic variants within six candidate genes along this pathway with serum methylmalonic acid (MMA) levels and frailty was evaluated in this same population of older women. METHODS Baseline measures were collected prior to folate fortification from 326 women in the Women's Health and Aging Studies I and II. Odds ratios and statistical tests were estimated for single SNP and haplotype via linear regression models for serum MMA, a marker for available vitamin B12, and in logistic regression models for frailty. RESULTS Fifty-six SNPs from CBS, MTHFR, MTR, MTRR, TCN1 and TCN2 genes were genotyped. Several SNPs in MTHFR, MTR and MTRR demonstrated a modest association to elevated MMA, while SNPs in TCN2 showed significant association to the frailty syndrome. TCN2 polymorphisms, particularly one SNP reported to be in perfect LD with functional variant Pro259Arg, were significantly associated with increased odds of frailty, after adjustment for age, presence of cardiovascular disease and elevated MMA (OR = 2.25, p-value = 0.009). CONCLUSIONS Using MMA as a marker for vitamin B12, these results suggest that TCN2 gene variants may lead to decreased vitamin B12 availability, leading to reduced energy metabolism, ultimately contributing to frailty pathology. Further studies to determine the biological role of functional TCN2 polymorphisms in frailty are needed.
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Affiliation(s)
- A M Matteini
- Johns Hopkins University, Baltimore, MD 21205, USA.
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Boiani R, Andreoni F, Serafini G, Bianconi I, Pierleoni R, Dominici S, Gorini F, Magnani M. Expression and characterization of the periplasmic cobalamin-binding protein of Photobacterium damselae subsp. piscicida. J Fish Dis 2009; 32:745-753. [PMID: 19490395 DOI: 10.1111/j.1365-2761.2009.01050.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Abstract Cobalamin (vitamin B(12)) is an essential cofactor in a variety of enzymatic reactions and most prokaryotes contain transport systems to import vitamin B(12). A gene coding for a periplasmic cobalamin-binding protein of Photobacterium damselae subsp. piscicida was identified by in silico analysis of sequences from a genomic library. The open reading frame was composed of 834 bp encoding a protein of 277 amino acids. The protein showed 61% identity with the vitamin B(12)-binding protein precursor of P. profundum, 53% identity with the corresponding protein of Vibrio parahaemolyticus and 43% identity with the periplasmic binding protein BtuF of Escherichia coli. The expression of the native protein was investigated in P. damselae subsp. piscicida, but BtuF was weakly expressed under normal conditions. To characterize the BtuF of P. damselae subsp. piscicida, the recombinant protein was expressed with a C-terminal His(6)-tag and purified; the molecular weight was estimated to be approximately 30 kDa. The protein does not contain any free thiol group, consistent with the view that the two cysteine residues are involved in a disulphide bond. The purified BtuF binds cyanocobalamin with an affinity constant of 6 +/- 2 microm.
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Affiliation(s)
- R Boiani
- Department of Biomolecular Science, University of Urbino Carlo Bo, 61032 Fano, Italy.
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Böttiger AK, Nilsson TK. Pyrosequencing assay for genotyping of the Transcobalamin II 776C>G polymorphism. Scandinavian Journal of Clinical and Laboratory Investigation 2009; 67:247-51. [PMID: 17366004 DOI: 10.1080/00365510601026542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The 776C>G polymorphism of the Transcobalamin II gene is located in a GC-rich region and TaqMan real-time polymerase chain reaction (PCR) does not yield satisfactory genotyping results. We therefore hypothesized that a method based on DNA sequencing would be needed for this single nucleotide polymorphism (SNP) analysis; Pyrosequencing technology was tested for this purpose. A Pyrosequencing protocol was developed, optimized and applied to a sample of 389 Swedish senior citizens. The three genotypes CC, CG, and GG consistently yielded typical programs that were readily distinguishable from each other. The prevalence of the mutated allele in the studied Swedish population was q=0.445. It is concluded that the TC II 776C>G polymorphism can be reliably genotyped by Pyrosequencing technology.
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Affiliation(s)
- A K Böttiger
- Department of Clinical Chemistry, Orebro University Hospital, Orebro, Sweden.
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Magnus P, Magnus EM, Berg K. Evidence for genetic effects on variation in plasma unsaturated transcobalamin II and cobalamin (vitamin B12). ACTA ACUST UNITED AC 2009; 33:180-6. [PMID: 6540893 DOI: 10.1111/j.1600-0609.1984.tb02394.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Unsaturated plasma transcobalamin II (UTC II) and cobalamin were measured in two selected age-groups of like-sexed mono- and dizygotic twins. For UTC II, a higher mean level was found in women than in men, and in the older (57 to 61 years) than in the younger (33 to 39 years) age group. Testing of genetic-environmental models revealed that variation in plasma levels of UTC II is almost exclusively genetically determined. More than 50% of the variation in cobalamin levels was accounted for by genes, the remainder being due to person-specific environmental factors (for older males no model gave a good fit). A negative correlation was noted between UTC II and cobalamin levels. The correlation coefficient was low, and the variation in UTC II accounted for only about 4% of the variation in the cobalamin level. This finding suggests that a pathologically high value of one of the variables may have clinical significance, regardless of the value of the other variable. For 22 patients studied longitudinally, a clear tendency to maintain plasma levels at constant levels over long periods of time was found, suggesting that certain degrees of deviation from these levels may have clinical relevance.
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Tanaka T, Scheet P, Giusti B, Bandinelli S, Piras MG, Usala G, Lai S, Mulas A, Corsi AM, Vestrini A, Sofi F, Gori AM, Abbate R, Guralnik J, Singleton A, Abecasis GR, Schlessinger D, Uda M, Ferrucci L. Genome-wide association study of vitamin B6, vitamin B12, folate, and homocysteine blood concentrations. Am J Hum Genet 2009; 84:477-82. [PMID: 19303062 PMCID: PMC2667971 DOI: 10.1016/j.ajhg.2009.02.011] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 02/17/2009] [Accepted: 02/25/2009] [Indexed: 11/25/2022] Open
Abstract
The B vitamins are components of one-carbon metabolism (OCM) that contribute to DNA synthesis and methylation. Homocysteine, a by-product of OCM, has been associated with coronary heart disease, stroke and neurological disease. To investigate genetic factors that affect circulating vitamin B6, vitamin B12, folate and homocysteine, a genome-wide association analysis was conducted in the InCHIANTI (N = 1175), SardiNIA (N = 1115), and BLSA (N = 640) studies. The top loci were replicated in an independent sample of 687 participants in the Progetto Nutrizione study. Polymorphisms in the ALPL gene (rs4654748, p = 8.30 x 10(-18)) were associated with vitamin B6 and FUT2 (rs602662, [corrected] p = 2.83 x 10(-20)) with vitamin B12 serum levels. The association of MTHFR, a gene consistently associated with homocysteine, was confirmed in this meta-analysis. The ALPL gene likely influences the catabolism of vitamin B6 while FUT2 interferes with absorption of vitamin B12. These findings highlight mechanisms that affect vitamin B6, vitamin B12 and homocysteine serum levels.
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Rutsch F, Gailus S, Miousse IR, Suormala T, Sagné C, Toliat MR, Nürnberg G, Wittkampf T, Buers I, Sharifi A, Stucki M, Becker C, Baumgartner M, Robenek H, Marquardt T, Höhne W, Gasnier B, Rosenblatt DS, Fowler B, Nürnberg P. Identification of a putative lysosomal cobalamin exporter altered in the cblF defect of vitamin B12 metabolism. Nat Genet 2009; 41:234-9. [PMID: 19136951 DOI: 10.1038/ng.294] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Accepted: 10/09/2008] [Indexed: 11/09/2022]
Abstract
Vitamin B(12) (cobalamin) is essential in animals for metabolism of branched chain amino acids and odd chain fatty acids, and for remethylation of homocysteine to methionine. In the cblF inborn error of vitamin B(12) metabolism, free vitamin accumulates in lysosomes, thus hindering its conversion to cofactors. Using homozygosity mapping in 12 unrelated cblF individuals and microcell-mediated chromosome transfer, we identified a candidate gene on chromosome 6q13, LMBRD1, encoding LMBD1, a lysosomal membrane protein with homology to lipocalin membrane receptor LIMR. We identified five different frameshift mutations in LMBRD1 resulting in loss of LMBD1 function, with 18 of the 24 disease chromosomes carrying the same mutation embedded in a common 1.34-Mb haplotype. Transfection of fibroblasts of individuals with cblF with wild-type LMBD1 rescued cobalamin coenzyme synthesis and function. This work identifies LMBRD1 as the gene underlying the cblF defect of cobalamin metabolism and suggests that LMBD1 is a lysosomal membrane exporter for cobalamin.
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Affiliation(s)
- Frank Rutsch
- Department of General Pediatrics, Münster University Children's Hospital, Albert-Schweitzer-Strasse 33, D-48149 Münster, Germany.
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Prasad C, Rosenblatt DS, Corley K, Cairney AEL, Rupar CA. Transcobalamin (TC) deficiency--potential cause of bone marrow failure in childhood. J Inherit Metab Dis 2008; 31 Suppl 2:S287-92. [PMID: 18956254 DOI: 10.1007/s10545-008-0864-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 08/21/2008] [Accepted: 09/22/2008] [Indexed: 11/27/2022]
Abstract
It is unusual for inborn errors of metabolism to be considered in the investigative work-up of pancytopenia. We report a family in which the proband presented with failure to thrive at 2 months of age and subsequent bone marrow failure. A previous sibling had died at 7 months of age with suspected leukaemia. Haematological findings in the proband were significant for pancytopenia, and bone marrow aspiration showed dysplastic changes in all cell lineages. Urinary organic acid analysis revealed elevated methylmalonic acid. The synthesis of transcobalamin II (transcobalamin, TC) by cultured fibroblasts was markedly reduced, confirming the diagnosis of TC deficiency. The proband and his younger asymptomatic sister (also found to have TC deficiency) were homozygous for R399X (c.1195C>T), a novel mutation resulting in the loss of the C- terminal 29 amino acids of TC, a highly conserved region. Response to parenteral vitamin B(12) in the proband was dramatic. At 6 years 3 months of age, physical examination is normal and developmental level is age appropriate. His sister is clinically asymptomatic and is also developing normally. Propionylcarnitine concentrations were not elevated in the newborn screening cards from the proband and sister, but that was for specimens retrieved from storage after 7 years and 5 years, respectively. Inherited and acquired cobalamin disorders should both be considered in the differential diagnosis of bone marrow failure syndromes in young children. Early detection of the metabolic causes of bone marrow failure can ensure prompt recovery in some cases involving the vitamin B(12) pathway.
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Affiliation(s)
- C Prasad
- Department of Pediatrics, Children's Hospital of Western Ontario and University of Western Ontario, London, Ontario, Canada.
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de Lau LML, van Meurs JBJ, Uitterlinden AG, Smith AD, Refsum H, Johnston C, Breteler MMB. Genetic variation in homocysteine metabolism, cognition, and white matter lesions. Neurobiol Aging 2008; 31:2020-2. [PMID: 19019492 DOI: 10.1016/j.neurobiolaging.2008.10.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 10/01/2008] [Accepted: 10/06/2008] [Indexed: 11/19/2022]
Abstract
Several studies have shown an association between homocysteine concentration and cognitive performance or cerebral white matter lesions. However, variations in genes encoding for enzymes and other proteins that play a role in homocysteine metabolism have hardly been evaluated in relation to these outcome measures. In the population-based Rotterdam Scan Study, we examined the association of seven polymorphisms of genes involved in homocysteine metabolism (MTHFR 677C>T, MTHFR 1298A>C, RFC 80G>A, TC 776C>G, MTR 2756A>G, MTRR 66A>G, and CBS 844ins68) with plasma total homocysteine, cognitive performance, and cerebral white matter lesions among 1011 non-demented elderly participants. Of all the studied polymorphisms, only MTHFR 677C>T was associated with homocysteine concentration. No significant relationship was observed for any of the polymorphisms with cognitive performance or severity of cerebral white matter lesions.
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Affiliation(s)
- Lonneke M L de Lau
- Department of Epidemiology & Biostatistics, Erasmus Medical Center, Rotterdam, The Netherlands.
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Biselli JM, Brumati D, Frigeri VF, Zampieri BL, Goloni-Bertollo EM, Pavarino-Bertelli EC. A80G polymorphism of reduced folate carrier 1 (RFC1) and C776G polymorphism of transcobalamin 2 (TC2) genes in Down's syndrome etiology. SAO PAULO MED J 2008; 126:329-32. [PMID: 19274320 DOI: 10.1590/s1516-31802008000600007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Accepted: 11/04/2008] [Indexed: 11/21/2022] Open
Abstract
CONTEXT AND OBJECTIVE There is evidence that polymorphisms of genes involved in folate metabolism may be associated with higher risk that mothers may bear a Down's syndrome (DS) child. This study therefore had the objective of investigating the A80G polymorphism of the reduced folate carrier 1 (RFC1) gene and the C776G polymorphism of the transcobalamin 2 (TC2) gene as maternal risk factors for DS among Brazilian women. DESIGN AND SETTING Analytical cross-sectional study with control group, at Faculdade de Medicina de São José do Rio Preto (Famerp). METHODS Sixty-seven mothers of DS individuals with free trisomy 21, and 113 control mothers, were studied. Molecular analysis of the polymorphisms was performed by means of the polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP), followed by electrophoresis on 2% agarose gel. RESULTS The frequencies of the polymorphic alleles were 0.51 and 0.52 for RFC1 80G, and 0.34 and 0.34 for TC2 776G, in the case and control groups, respectively. Thus, there were no differences between the groups in relation to either the allele or the genotype frequency, for both polymorphisms (P = 0.696 for RFC1 A80G; P = 0.166 for TC2 C776G; P = 0.268 for combined genotypes). CONCLUSION There was no evidence of any association between the RFC1 A80G and TC2 C776G polymorphisms and the maternal risk of DS in the sample evaluated.
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Affiliation(s)
- Joice Matos Biselli
- Genetics and Molecular Biology Research Unit, Department of Molecular Biology, Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, São Paulo, Brazil
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Verkleij-Hagoort AC, van Driel LMJW, Lindemans J, Isaacs A, Steegers EAP, Helbing WA, Uitterlinden AG, Steegers-Theunissen RPM. Genetic and lifestyle factors related to the periconception vitamin B12 status and congenital heart defects: a Dutch case-control study. Mol Genet Metab 2008; 94:112-9. [PMID: 18226574 DOI: 10.1016/j.ymgme.2007.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 12/04/2007] [Accepted: 12/04/2007] [Indexed: 01/29/2023]
Abstract
Maternal hyperhomocysteinemia is associated with congenital heart defects (CHDs) in the offspring. A low periconception vitamin B12 status is determined by genetic and lifestyle factors and causes hyperhomocysteinemia. We investigated methionine synthase reductase (MTRR) and transcobalamin II (TC) genes and maternal intake and serum concentrations of vitamin B12 in association with CHD risk. Seventeen months after the index-pregnancy, we studied 230 children with a CHD and 251 non-malformed children and their parents. Data were collected on current and periconception maternal vitamin supplement use and maternal dietary vitamin B12 intake of the month before the study moment. Blood samples were taken for the determination of MTRR A66G and TC C776G genotypes in families and maternal serum vitamin B12 concentrations. Transmission disequilibrium tests and univariate and multivariate analyses were applied. Allele transmissions were not significantly distorted. The MTRR and TC genotypes did not significantly affect CHD risk. Neither polymorphisms in mothers and/or children revealed significant interactions nor in combination with low vitamin B12 intake. Low maternal serum vitamin B12 combined with the maternal or child's MTRR 66 GG genotype resulted in odds ratios of 1.4 (95% confidence interval 0.6-3.5) and 1.3 (0.5-3.4), respectively. The TC 776 GG genotype in mothers and children revealed risk estimates of 2.2 (0.7-7.1) and 1.9 (0.5-7.4), respectively. In conclusion, MTRR 66 GG and TC 776 GG genotypes in mothers and children may contribute to the risk of CHDs, particularly when the maternal vitamin B12 status is low. The future enlargement of our sample size might demonstrate significant associations.
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Affiliation(s)
- Anna C Verkleij-Hagoort
- Department of Obstetrics, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Center, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands
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Hazra A, Wu K, Kraft P, Fuchs CS, Giovannucci EL, Hunter DJ. Twenty-four non-synonymous polymorphisms in the one-carbon metabolic pathway and risk of colorectal adenoma in the Nurses' Health Study. Carcinogenesis 2007; 28:1510-9. [PMID: 17389618 DOI: 10.1093/carcin/bgm062] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dietary folate and alcohol consumption as well as polymorphic variants in one-carbon metabolism genes may modulate risk of colorectal adenoma through aberrant DNA methylation and altered nucleotide synthesis and repair. We assessed the association of 24 non-synonymous single nucleotide polymorphisms (nsSNPs) in 13 genes in the one-carbon metabolism pathway and risk of colorectal adenoma in 556 incident cases and 557 controls nested in the Nurses' Health Study. Most of the SNPs were not associated with risk of colorectal adenoma. We did, however, observe a modest increased risk among carriers of the transcobalamin (TCN) II 259 Pro/Arg + Arg/Arg variant (odds ratio 1.48, 95% confidence interval 1.09-2.02) for colorectal adenoma. The TCN II Pro259Arg polymorphism may affect TCN binding and transport of vitamin B(12) and thus warrants further investigation of its biological function. In addition, the methionine synthase reductase (MTRR) Arg415Cys and MTRR Ser284Thr variant carriers, also in the vitamin B(12) pathway, have suggestive associations with advanced colorectal adenoma (defined as being larger than 1 cm, villous, tubular-villous or carcinoma in situ histology). We observed significant evidence for departure from multiplicative interaction for the betaine-homocysteine methyltransferase (BHMT) Arg239Gln with dietary methyl status (based on intake of dietary folate, methionine and alcohol intake) in relation to colorectal adenoma; no such interaction was observed for the other 23 SNPs. Further investigation is required to validate the association of the polymorphisms in the one-carbon metabolic genes and risk of colorectal adenoma.
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Affiliation(s)
- Aditi Hazra
- Program in Molecular and Genetic Epidemiology, Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
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Guéant JL, Chabi NW, Guéant-Rodriguez RM, Mutchinick OM, Debard R, Payet C, Lu X, Villaume C, Bronowicki JP, Quadros EV, Sanni A, Amouzou E, Xia B, Chen M, Anello G, Bosco P, Romano C, Arrieta HR, Sánchez BE, Romano A, Herbeth B, Anwar W, Namour F. Environmental influence on the worldwide prevalence of a 776C->G variant in the transcobalamin gene (TCN2). J Med Genet 2007; 44:363-7. [PMID: 17220211 PMCID: PMC2740879 DOI: 10.1136/jmg.2006.048041] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND A 776C-->G variant (dbSNP ID: rs1801198) in the transcobalamin gene (TCN2; MIM# 275350) decreases the cellular and plasma concentration of transcobalamin and thereby influences the cellular availability of vitamin B(12). OBJECTIVE To evaluate the worldwide prevalence of this variant and its association with homocysteine plasma level. METHODS The study was performed in 1433 apparently healthy subjects, including Afro-Americans and Afro-Africans and in 251 Afro-Africans participants with severe malaria. RESULTS The frequencies of the 776G allele were the highest in China (0.607; 95% CI 0.554 to 0.659), low in West Africa (Bénin and Togo, 0.178; 0.154 to 0.206), and intermediate in France (0.445; 0.408 to 0.481), Italy (0.352; 0.299 to 0.409), Morocco (0.370; 0.300 to 0.447) and Mexico (0.374; 0.392 to 0.419). The 776G genotype was more frequent in Afro-Americans from New York (16.7; 8.4 to 30.7) and in Afro-African patients with severe malaria (6.0%; 95% CI 3.7 to 9.6) than in healthy Afro-African volunteers (p = 0.0004 and p = 0.033, respectively), while no difference was observed for MTHFR 677TT and 677T alleles. A disequilibrium of TCN2 genotype distribution was recorded in patients with severe malaria, with a twofold higher GG genotype than expected (p = 0.010). An association between the TCN2 polymorphism and homocysteine was observed only in Mexico and France, the two countries with the highest rate of low plasma concentration of vitamin B(12) (<100 pmol/l). CONCLUSION Given the dramatic heterogeneity of the 776G allele frequency worldwide, this polymorphism may be prone to a selective pressure or confers an evolutionary advantage in confronting environmental factors, one of which is malaria.
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Affiliation(s)
- Jean-Louis Guéant
- Inserm U-724, Cellular and Molecular Pathology in Nutrition, Faculté de Médecine, University Henry Poincaré of Nancy, Vandoeuvre lès Nancy, France.
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Pereira AC, Lourenço DM, Maffei FH, Morelli VM, Rollo HA, Zago MA, Vannucchi H, Franco RF. A transcobalamin gene polymorphism and the risk of venous thrombosis. The BRATROS (Brazilian Thrombosis Study). Thromb Res 2007; 119:183-8. [PMID: 16530812 DOI: 10.1016/j.thromres.2006.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 12/20/2005] [Accepted: 01/23/2006] [Indexed: 11/23/2022]
Affiliation(s)
- Ana C Pereira
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Brazil.
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James SJ, Melnyk S, Jernigan S, Cleves MA, Halsted CH, Wong DH, Cutler P, Bock K, Boris M, Bradstreet JJ, Baker SM, Gaylor DW. Metabolic endophenotype and related genotypes are associated with oxidative stress in children with autism. Am J Med Genet B Neuropsychiatr Genet 2006; 141B:947-56. [PMID: 16917939 PMCID: PMC2610366 DOI: 10.1002/ajmg.b.30366] [Citation(s) in RCA: 406] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Autism is a behaviorally defined neurodevelopmental disorder usually diagnosed in early childhood that is characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social withdrawal. Although both genetic and environmental factors are thought to be involved, none have been reproducibly identified. The metabolic phenotype of an individual reflects the influence of endogenous and exogenous factors on genotype. As such, it provides a window through which the interactive impact of genes and environment may be viewed and relevant susceptibility factors identified. Although abnormal methionine metabolism has been associated with other neurologic disorders, these pathways and related polymorphisms have not been evaluated in autistic children. Plasma levels of metabolites in methionine transmethylation and transsulfuration pathways were measured in 80 autistic and 73 control children. In addition, common polymorphic variants known to modulate these metabolic pathways were evaluated in 360 autistic children and 205 controls. The metabolic results indicated that plasma methionine and the ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH), an indicator of methylation capacity, were significantly decreased in the autistic children relative to age-matched controls. In addition, plasma levels of cysteine, glutathione, and the ratio of reduced to oxidized glutathione, an indication of antioxidant capacity and redox homeostasis, were significantly decreased. Differences in allele frequency and/or significant gene-gene interactions were found for relevant genes encoding the reduced folate carrier (RFC 80G > A), transcobalamin II (TCN2 776G > C), catechol-O-methyltransferase (COMT 472G > A), methylenetetrahydrofolate reductase (MTHFR 677C > T and 1298A > C), and glutathione-S-transferase (GST M1). We propose that an increased vulnerability to oxidative stress (endogenous or environmental) may contribute to the development and clinical manifestations of autism.
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Affiliation(s)
- S Jill James
- Department of Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas 72202, USA.
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Martinelli M, Scapoli L, Palmieri A, Pezzetti F, Baciliero U, Padula E, Carinci P, Morselli PG, Carinci F. Study of four genes belonging to the folate pathway: transcobalamin 2 is involved in the onset of non-syndromic cleft lip with or without cleft palate. Hum Mutat 2006; 27:294. [PMID: 16470748 DOI: 10.1002/humu.9411] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cleft lip with or without cleft palate (CL/P) is the most common inborn craniofacial anomaly. Affected individuals require extensive medical and psychosocial support. Although CL/P has a complex and poorly understood etiology, increasing evidence of folate pathway involvement has been collected. So far, only the MTHFR gene has been extensively investigated as a risk factor for CL/P, while little has been done to test genetic variations in the folate biosynthetic pathways that may influence the infant's susceptibility to these birth defects. To date, this paper presents the first attempt to verify the involvement of four genes belonging to the folate pathway in nonsyndromic cleft onset. We used a case-parent triad design to test for linkage disequilibrium in the case of seven SNPs mapping on four different genes: transcobalamin 1 and 2 (TCN1 and TCN2), methionine synthase (MTR), and MTR reductase (MTRR). Our finding suggests that TCN2 is involved in causing CL/P. Indeed, significant overtransmission of the C allele was observed at the polymorphism c.776C>G (p.Pro259Arg) to the affected offspring (P=0.01). Results obtained with additional TCN2 polymorphisms suggest that c.776C>G may be functionally related to CL/P. However, because conflicting data exist with regard to the effect of the polymorphism in transcobalamin 2 function or in perturbing plasma levels of key molecules in the folate pathway, further investigation is warranted to confirm our data.
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Affiliation(s)
- Marcella Martinelli
- Department of Morphology and Embryology, University of Ferrara, Ferrara, Italy
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40
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Aléssio ACM, Höehr NF, Siqueira LH, Bydlowski SP, Annichino-Bizzacchi JM. Polymorphism C776G in the transcobalamin II gene and homocysteine, folate and vitamin B12 concentrations. Association with MTHFR C677T and A1298C and MTRR A66G polymorphisms in healthy children. Thromb Res 2006; 119:571-7. [PMID: 16820193 DOI: 10.1016/j.thromres.2006.05.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 05/10/2006] [Accepted: 05/11/2006] [Indexed: 11/21/2022]
Abstract
One of the etiologies of hyperhomocysteinemia is decreased vitamin B(12). Genetic variation in the transcobalamin II gene, the transporter of vitamin B(12) to the cells, may produce altered homocysteine levels. We determined transcobalamin II C776G polymorphism, homocysteine, folate and vitamin B(12) levels and analyzed the interactive effect with the methylenetetrahydrofolate reductase C677T and A1298C and methionine synthase reductase A66G polymorphisms in 207 healthy Brazilian children. The prevalence of GG genotype of transcobalamin II C776G polymorphism in this Brazilian population, a highly miscigeneous population was 12.5% and the statistical analysis showed that this population is in Hardy-Weinberg equilibrium, it could be considered representative of the general population. We observed a significant increase in homocysteine in the 776GG vs. 776CC genotype, corroborating the influence of age as a determinant of homocysteine in relation to this polymorphism. When we analyzed vitamin B(12) and its relationship with the C776G polymorphism, we found no significant differences. Only 776CG/66AA or 776GG/66AG genotypes presented a significant increase in homocysteine when compared with other groups. In the multivariate analysis, transcobalamin II C776G (CC/CG vs. GG), methylenetetrahydrofolate reductase C677T (CC/CT vs. TT), folate, gender and age presented statistical significance in relation to the homocysteine. These can be considered independent risk factors for hyperhomocysteinemia in this children group. Our results, if confirmed in other populations, highlight the necessity for investigation of the transcobalamin II C776G polymorphism in the research for hyperhomocysteinemia risk factors.
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Affiliation(s)
- Ana C M Aléssio
- Hematology-Hemotherapy Center, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
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41
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Wuerges J, Garau G, Geremia S, Fedosov SN, Petersen TE, Randaccio L. Structural basis for mammalian vitamin B12 transport by transcobalamin. Proc Natl Acad Sci U S A 2006; 103:4386-91. [PMID: 16537422 PMCID: PMC1450181 DOI: 10.1073/pnas.0509099103] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cobalamin (Cbl, vitamin B(12)) serves for two essential cofactors in mammals. The pathway for its intestinal absorption, plasma transport, and cellular uptake uses cell surface receptors and three Cbl-transporting proteins, haptocorrin, intrinsic factor, and transcobalamin (TC). We present the structure determination of a member of the mammalian Cbl-transporter family. The crystal structures of recombinant human and bovine holo-TCs reveal a two-domain architecture, with an N-terminal alpha(6)-alpha(6) barrel and a smaller C-terminal domain. One Cbl molecule in base-on conformation is buried inside the domain interface. Structural data combined with previous binding assays indicate a domain motion in the first step of Cbl binding. In a second step, the weakly coordinated ligand H(2)O at the upper axial side of added H(2)O-Cbl is displaced by a histidine residue of the alpha(6)-alpha(6) barrel. Analysis of amino acid conservation on TC's surface in orthologous proteins suggests the location of the TC-receptor-recognition site in an extended region on the alpha(6)-alpha(6) barrel. The TC structure allows for the mapping of sites of amino acid variation due to polymorphisms of the human TC gene. Structural information is used to predict the overall fold of haptocorrin and intrinsic factor and permits a rational approach to the design of new Cbl-based bioconjugates for diagnostic or therapeutic drug delivery.
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Affiliation(s)
- Jochen Wuerges
- *Centre of Excellence in Biocrystallography, Department of Chemical Sciences, University of Trieste, Via L. Giorgieri 1, I-34127 Trieste, Italy; and
| | - Gianpiero Garau
- *Centre of Excellence in Biocrystallography, Department of Chemical Sciences, University of Trieste, Via L. Giorgieri 1, I-34127 Trieste, Italy; and
| | - Silvano Geremia
- *Centre of Excellence in Biocrystallography, Department of Chemical Sciences, University of Trieste, Via L. Giorgieri 1, I-34127 Trieste, Italy; and
- To whom correspondence should be addressed. E-mail:
| | - Sergey N. Fedosov
- Protein Chemistry Laboratory, Department of Molecular Biology, University of Aarhus, Science Park, Gustav Wieds Vey 10, 8000 Aarhus C, Denmark
| | - Torben E. Petersen
- Protein Chemistry Laboratory, Department of Molecular Biology, University of Aarhus, Science Park, Gustav Wieds Vey 10, 8000 Aarhus C, Denmark
| | - Lucio Randaccio
- *Centre of Excellence in Biocrystallography, Department of Chemical Sciences, University of Trieste, Via L. Giorgieri 1, I-34127 Trieste, Italy; and
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Abstract
We present a case of intracellular vitamin B12 deficiency presenting with confusion, subacute combined degeneration of the cord, megaloblastic anaemia and intrinsic factor antibodies in the serum. Diagnosis was delayed by a normal serum B12 level and was confirmed by a grossly elevated serum homocysteine. There was a dramatic response to steroids. The patient was heterozygous for the transcobalamin (TC) II polymorphism 776C --> G. This case demonstrates the importance of functional assessment of intracellular B12 activity (e.g. serum homocysteine) in excluding B12 deficiency, the role of steroids in pernicious anaemia and a possible clinical correlation of a TCII polymorphism.
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Affiliation(s)
- Daniel P Gale
- Department of Neurology, St Mary's Hospital, London, UK.
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Warden DR, Refsum H. Detection of single-nucleotide polymorphisms by PCR with universal energy transfer-labeled primers: application to folate- and cobalamin-related genes. Clin Chem 2005; 51:1713-6. [PMID: 16037414 DOI: 10.1373/clinchem.2004.045195] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Donald R Warden
- Department of Pharmacology, University of Oxford, Oxford, UK
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von Castel-Dunwoody KM, Kauwell GPA, Shelnutt KP, Vaughn JD, Griffin ER, Maneval DR, Theriaque DW, Bailey LB. Transcobalamin 776C->G polymorphism negatively affects vitamin B-12 metabolism. Am J Clin Nutr 2005; 81:1436-41. [PMID: 15941899 DOI: 10.1093/ajcn/81.6.1436] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND A common genetic polymorphism [transcobalamin (TC) 776C-->G] may affect the function of transcobalamin, the protein required for vitamin B-12 cellular uptake and metabolism. Remethylation of homocysteine is dependent on the production of 5-methyltetrahydrofolate and adequate vitamin B-12 for the methionine synthase reaction. OBJECTIVES The objectives were to assess the influence of the TC 776C--> G polymorphism on concentrations of the transcobalamin-vitamin B-12 complex (holo-TC) and to determine the combined effects of the TC 776C-->G and methylenetetrahydrofolate reductase (MTHFR) 677C-->T polymorphisms and vitamin B-12 status on homocysteine concentrations. DESIGN Healthy, nonpregnant women (n = 359; aged 20-30 y) were screened to determine plasma vitamin B-12, serum holo-TC, and plasma homocysteine concentrations and TC 776C-->G and MTHFR 677C-->T genotypes. RESULTS The serum holo-TC concentration for women with the variant TC 776 GG genotype was significantly different (P = 0.0213) from that for subjects with the CC genotype (74 +/- 37 and 87 +/- 33 pmol/L, respectively). An inverse relation was observed between plasma homocysteine concentrations and both serum holo-TC (P </= 0.0001) and plasma vitamin B-12 (P </= 0.0001) concentrations, regardless of genotype. CONCLUSIONS These data suggest that the TC 776C-->G polymorphism negatively affects the serum holo-TC concentration and provide additional evidence that vitamin B-12 status modulates the homocysteine concentration in this population.
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Affiliation(s)
- Kristina M von Castel-Dunwoody
- Food Science and Human Nutrition Department and the General Clinical Research Center, University of Florida, Gainesville, FL 32611, USA
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Zetterberg H, Nexö E, Minthon L, Boson R, Regland B, McCaddon A, Blennow KA. The transcobalamin 776C > G polymorphism may be a modifiable genetic risk factor for Alzheimer's disease. Int Psychogeriatr 2005; 17:329-31. [PMID: 16050442 DOI: 10.1017/s1041610205222068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Guéant JL, Anello G, Bosco P, Guéant-Rodríguez RM, Romano A, Barone C, Gérard P, Romano C. Homocysteine and related genetic polymorphisms in Down's syndrome IQ. J Neurol Neurosurg Psychiatry 2005; 76:706-9. [PMID: 15834031 PMCID: PMC1739618 DOI: 10.1136/jnnp.2004.039875] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE Down's syndrome (DS) is the most frequent genetic cause of Alzheimer-type dementia. Its metabolic phenotype involves an increased trans-sulphuration of homocysteine. The aim of the present study was to investigate the influence of homocysteinaemia (t-Hcys), folate, vitamin B(12), and related polymorphisms on intelligence quotient (IQ) in DS. METHODS The IQ of 131 patients with trisomy 21 from a specialist centre in Sicily was determined and classified according to DMS-IV. The effects of age, folate, vitamin B(12), t-Hcys, and genetic polymorphisms on IQ were evaluated separately and in combination using regression analyses. RESULTS IQ was significantly lower in DS patients with t-Hcys >7.5 micromol/l (median) and in those who were carriers of methylenetetrahydrofolate reductase (MTHFR) 677 T allele and of methylenetetrahydrofolate reductase 677 T and transcobalamin 776 G combined alleles (p = 0.0013, p = 0.0165, and p = 0.0074, respectively). The IQ correlated significantly with t-Hcys and folate in single and multiple regression analyses, independently of age. In addition, t-Hcys >9.6 micromol/l (upper quartile) was found to be associated with low IQ (<40, median of study group) with an odds ratio of 2.61 (p = 0.0203). The odds ratio was increased by threefold in carriers of MTHFR 677T allele. The MTHFR 677T allele/transcobalamin 776 G allele combination was associated with the risk of DS patients to have an IQ less that the median with an odds ratio of 2.68 (95% CI 1.26 to 5.70, p = 0.0104). CONCLUSION This study found evidence of an association between t-Hcys and MTHFR 677 T and transcobalamin 776 G alleles with IQ in patients with DS. The association may be related to a defective remethylation of homocysteine, affecting IQ.
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Affiliation(s)
- J-L Guéant
- IRCCS, Oasi Maria SS-Institute for Research on Mental Retardation and Brain Aging, Troina (EN), Italy.
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Swanson DA, Pangilinan F, Mills JL, Kirke PN, Conley M, Weiler A, Frey T, Parle-McDermott A, O'Leary VB, Seltzer RR, Moynihan KA, Molloy AM, Burke H, Scott JM, Brody LC. Evaluation of transcobalamin II polymorphisms as neural tube defect risk factors in an Irish population. ACTA ACUST UNITED AC 2005; 73:239-44. [PMID: 15782407 DOI: 10.1002/bdra.20122] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Decreased maternal folate levels are associated with having a child with a neural tube defect (NTD), and periconceptual folic acid supplementation reduces this risk by >50%. Vitamin B(12) (as methylcobalamin) is a cofactor for methionine synthase, an enzyme that plays a key role in folate metabolism. Alterations in vitamin B(12) metabolism may influence the development of NTDs. Low levels of maternal plasma vitamin B(12) and reduced binding of vitamin B(12) by transcobalamin II (TCII) are independent risk factors for NTDs. TCII levels are altered in the amniotic fluid of pregnancies affected by NTDs. Given this evidence, inherited variants in genes involved in vitamin B(12) trafficking such as TCII are candidate NTD risk factors. METHODS We used case/control and family-based association methods to investigate whether six common polymorphisms in the TCII gene influence NTD risk. TCII genotypes were determined for more than 300 Irish NTD families and a comparable number of Irish controls. RESULTS Allele and genotype frequencies for each polymorphism did not differ between family members and controls. CONCLUSIONS These six TCII polymorphisms do not strongly influence NTD risk in the Irish population. The Supplementary Material for this article can be found on the Birth Defects Research (Part A) website: http://www.mrw.interscience.wiley.com/suppmat/1542-0752/suppmat/2005/73/v73.4.swanson.html
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Affiliation(s)
- Deborah A Swanson
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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Abstract
Women who take folic acid in the periconceptional period greatly reduce their chances of having a child with a neural tube defect (NTD). Using multivitamins may also reduce the risk of having a child with an omphalocele. In this study, we tested single nucleotide polymorphisms in folate-related enzyme genes for association with omphalocele. Polymorphisms in methylenetetrahydrofolate reductase (MTHFR), methylenetetrahydrofolate dehydrogenase (MTHFD1), the reduced folate carrier (SLC19A1), and transcobalamin II (TCN2) were examined in 25 children with euploid omphalocele and 59 matched controls. Omphalocele cases were significantly more likely to carry the T allele of MTHFR 677C-->T, a known risk factor for NTDs (odds ratio 3.50, 95% confidence interval 1.07-11.47, P=0.035). The MTHFD1 R653Q, SLC19A1 R27H, and TCN2 P259R polymorphisms showed no significant association with omphalocele. In this small study, the thermolabile variant of MTHFR, 677C-->T, was associated with an increased risk for omphalocele. This variant causes reduced enzyme activity, thus suggesting a mechanism by which multivitamins with folic acid might prevent omphalocele. Additional investigation is required.
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Affiliation(s)
- James L Mills
- Division of Epidemiology, Statistics and Prevention Research, NICHD, NIH, DHHS, Bethesda, Maryland 20892, USA.
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Kalra S, Li N, Yammani RR, Seetharam S, Seetharam B. Cobalamin (vitamin B12) binding, phylogeny, and synteny of human transcobalamin. Arch Biochem Biophys 2004; 431:189-96. [PMID: 15488467 DOI: 10.1016/j.abb.2004.08.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 08/09/2004] [Indexed: 10/26/2022]
Abstract
Selected residues in a highly conserved 15-residue region, 174SVDTAAMAGLAFTC L188 of human transcobalamin (TC), a cobalamin (Cbl: vitamin B12) binding protein, were subjected to site-directed mutagenesis. The mutant constructs were expressed in TC-deficient fibroblasts or in vitro to assess the effect of these mutations on Cbl binding. Phylogenetic analyses and protein parsimony indicated that TC evolved earlier than other mammalian Cbl-binding proteins, intrinsic factor and haptocorrins, and divergence occurred between mouse/rat and human dispersing TC gene to different chromosomes. These studies show that (a) two of the three polar residues, S174, T177, or D176 and two of the three conserved alanine residues, A179 and A184 present in the 15-residue evolutionary conserved region are essential for Cbl-binding by human TC, and (b) TC gene is transferred in a syntenic manner to different chromosomes, at least before the divergence of mouse/rat and human.
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Affiliation(s)
- Seema Kalra
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin and Clement Zablocki VA Medical Center, Milwaukee, WI 53295, USA
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Anwar W, Gérard P, Moutabarrek A, Namour F, Guéant JL. End-stage renal disease increases plasma transcobalamin and neutralizes influence of TCN 776C>G polymorphism. Kidney Int 2004; 66:2092-3. [PMID: 15496191 DOI: 10.1111/j.1523-1755.2004.989_9.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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