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Al-Batayneh KM, Salim Al Zoubi M, Al-Trad B, Hussein E, Al Khateeb W, Aljabali AAA, Bodoor K, Shehab M, Al Hamad MA, Eaton GJ, Cornelison CT. Homologous G776G Variant of Transcobalamin-II Gene is Linked to Vitamin B12 Deficiency. INT J VITAM NUTR RES 2019; 90:151-155. [PMID: 30761942 DOI: 10.1024/0300-9831/a000536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vitamin B12 (Cobalamin) deficiency, due to improper internalization of cobalamin, is a metabolic disorder prevalent in impoverished and elderly populations and is associated with megaloblastic anemia and dementia. It has been suggested that mutations in transcobalamin II (TCN2) or gastric intrinsic factor (GIF) proteins can alter their binding efficiency to cobalamin or reduce the ability of their receptors to internalize them. In this case-control study, the correlation between vitamin B12 deficiency and alternative alleles of TCN2 and GIF was investigated in a Jordanian population. One hundred individuals with vitamin B12 deficiency (B12 < 200 mg/mL) were enrolled in our study to evaluate the TCN2 and GIF polymorphisms. The control group (B12 > 200 mg/mL) included 100 individuals. Our results indicated a significant association between the homologous variant of the TCN2 gene (G776G) and vitamin B12 deficiency, and an intermediate phenotype in heterozygous individuals (p < 0.001, OR = 5.6, 95% CI = 2.95 to 10.63). The GIF gene, however, showed no correlation between the A68G variant and vitamin B12 deficiency (p = 0.2). This study expounds the association of TCN2 polymorphism with cobalamin levels in a Jordanian population and highlights the necessity of further studies to elucidate the molecular basis and impact of TCN2 and GIF genes polymorphisms on vitamin B12 deficiency and associated disorders.
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Affiliation(s)
- Khalid M Al-Batayneh
- Department of Biological Sciences, Faculty of Science, Yarmouk University, Irbid, Jordan
| | - Mazhar Salim Al Zoubi
- Department of Biological Sciences, Faculty of Science, Yarmouk University, Irbid, Jordan.,Department of Basic Medical Sciences, Faculty of Medicine, Yarmouk University, Irbid, Jordan
| | - Bahaa Al-Trad
- Department of Biological Sciences, Faculty of Science, Yarmouk University, Irbid, Jordan
| | - Emad Hussein
- Department of Biological Sciences, Faculty of Science, Yarmouk University, Irbid, Jordan.,Department of Food Science and Human Nutrition, College of Applied Sciences, A'Sharqiyah University, Ibra, Oman
| | - Wesam Al Khateeb
- Department of Biological Sciences, Faculty of Science, Yarmouk University, Irbid, Jordan
| | | | - Khaldon Bodoor
- Department of Applied Biology, Faculty of Science and Arts, Jordan University of Science and Technology, Irbid, Jordan
| | - Murad Shehab
- Department of Biological Sciences, Faculty of Science, Yarmouk University, Irbid, Jordan
| | - Mohammad A Al Hamad
- Department of Pathology, College of Medicine, Imam Abdulrahman Bin Faisal University (IAU), Dammam, Kingdom of Saudi Arabia
| | - Greg J Eaton
- Department of Biological Sciences, Rowan University, New Jersey, USA
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Allen LH, Miller JW, de Groot L, Rosenberg IH, Smith AD, Refsum H, Raiten DJ. Biomarkers of Nutrition for Development (BOND): Vitamin B-12 Review. J Nutr 2018; 148:1995S-2027S. [PMID: 30500928 PMCID: PMC6297555 DOI: 10.1093/jn/nxy201] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/06/2017] [Accepted: 08/02/2018] [Indexed: 12/31/2022] Open
Abstract
This report on vitamin B-12 (B12) is part of the Biomarkers of Nutrition for Development (BOND) Project, which provides state-of-the art information and advice on the selection, use, and interpretation of biomarkers of nutrient exposure, status, and function. As with the other 5 reports in this series, which focused on iodine, folate, zinc, iron, and vitamin A, this B12 report was developed with the assistance of an expert panel (BOND B12 EP) and other experts who provided information during a consultation. The experts reviewed the existing literature in depth in order to consolidate existing relevant information on the biology of B12, including known and possible effects of insufficiency, and available and potential biomarkers of status. Unlike the situation for the other 5 nutrients reviewed during the BOND project, there has been relatively little previous attention paid to B12 status and its biomarkers, so this report is a landmark in terms of the consolidation and interpretation of the available information on B12 nutrition. Historically, most focus has been on diagnosis and treatment of clinical symptoms of B12 deficiency, which result primarily from pernicious anemia or strict vegetarianism. More recently, we have become aware of the high prevalence of B12 insufficiency in populations consuming low amounts of animal-source foods, which can be detected with ≥1 serum biomarker but presents the new challenge of identifying functional consequences that may require public health interventions.
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Affiliation(s)
- Lindsay H Allen
- USDA, Agricultural Research Service Western Human Nutrition Research Center, University of California, Davis, CA
| | - Joshua W Miller
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ
| | - Lisette de Groot
- Division of Human Nutrition, Wageningen University, Wageningen, Netherlands
| | - Irwin H Rosenberg
- Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA
| | - A David Smith
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Helga Refsum
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Daniel J Raiten
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), NIH, Bethesda, MD
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The TCN2 776C>G polymorphism correlates with vitamin B12 cellular delivery in healthy adult populations. Clin Biochem 2010; 43:645-9. [DOI: 10.1016/j.clinbiochem.2010.01.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 01/26/2010] [Accepted: 01/27/2010] [Indexed: 12/17/2022]
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Transcobalamin C776G genotype modifies the association between vitamin B12 and homocysteine in older Hispanics. Eur J Clin Nutr 2010; 64:503-9. [PMID: 20216556 PMCID: PMC2864787 DOI: 10.1038/ejcn.2010.20] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Background A common polymorphism, C776G, in the plasma B12 transport protein transcobalamin (TC), encodes for either proline or arginine at codon 259. This polymorphism may affect the affinity of TC for B12 and subsequent delivery of B12 to tissues. Methods TC genotype and its associations with indicators of B12 status, including total B12, holotranscobalamin (holoTC), methylmalonic acid, and homocysteine, were evaluated in a cohort of elderly Latinos (N=554, age 60–93y) from the Sacramento Area Latino Study on Aging (SALSA). Results The distribution of TC genotypes was 41.3% homozygous reference (776CC) and 11.6% homozygous variant (776GG). No differences between the homozygous genotypes were observed in total B12, holoTC, methylmalonic acid, or homocysteine. The holoTC/total B12 ratio was lower in the 776GG group compared with the 776CC group (p=0.04). Significant interactions of TC genotype with total B12 (p=0.04) and with holoTC (p≤0.03) were observed such that mean homocysteine concentrations and the odds ratios for hyperhomocysteinemia (>13 µmol/L) were higher in the 776CC subjects compared with all carriers of the G allele (776CG and 776GG combined) when total B12 (<156 pmol/L) or holoTC (<35 pmol/L) were low. Conclusions This population of older Latinos has a lower prevalence of the TC 776GG variant than reported for Caucasian populations. The association between vitamin B12 and homocysteine concentrations is modified by TC 776 genotype. It remains to be determined if the TC C776G polymorphism has a significant effect on the hematological and neurological manifestations of B12 deficiency or on vascular and other morbidities associated with hyperhomocysteinemia.
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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] [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] [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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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] [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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