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Articles

A Common Mutation A1298C in Human Methylenetetrahydrofolate Reductase Gene: Association with Plasma Total Homocysteine and Folate Concentrations¹

Gideon Friedman^*, Netta Goldschmidt^*, Yechiel Friedlander, Arie Ben-Yehuda^*, Jacob Selhub^**, Sharona Babaey^*, Malka Mendel, Miriam Kidron and Hanoch Bar-On

^* Geriatric Unit, Lipid Research Laboratory; Department of Social Medicine, School of Public Health and Community Medicine and Diabetes Unit, Hebrew University Hadassah Medical Center, Jerusalem, Israel; and ^** Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center, Tufts, New England Medical Center, Boston, MA

²To whom correspondence should be addressed.

	ABSTRACT

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Methylenetetrahydrofolate reductase (MTHFR) is one of the main regulatory enzymes of homocysteine metabolism. Previous studies revealed that a common mutation in MTHFR gene C677T is related to hyperhomocysteinemia and occlusive vascular pathology. In the current study, we determined the prevalence of a newly described mutation in the human MTHFR gene A1298C, and the already known C677T mutation, and related them to plasma total homocysteine and folate concentrations. We studied 377 Jewish subjects, including 190 men and 186 women aged 56.8 ± 13 y (range 32–95 y). The frequency of the homozygotes for the A1298C and the C677T MTHFR mutations was common in the Jewish Israeli population (0.34 and 0.37, respectively). Subjects homozygous (TT) for the C677T mutation had significantly greater plasma total homocysteine concentrations (P < 0.01) than subjects without the mutation (CC). Homozygotes (CC) for the A1298C mutation did not have elevated plasma total homocysteine concentrations. Our study indicated that subjects with the 677CC/1298CC genotype had significantly lower concentrations (P < 0.05) than those with a 677CC/1298AA genotype. Neither mutation (the A1298C and the C677T) was associated with established cardiovascular risk factors such as hypertension, elevated total cholesterol or body mass index.

KEY WORDS: • methylenetetrahydrofolate reductase mutation • folate • homocysteine • humans

	INTRODUCTION

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Elevated plasma total homocysteine concentrations were recognized as a major risk factor for thrombosis and atherosclerosis (Berwanger et al. 1995 , D'Angelo and Selhub 1997 , Glueck et al. 1995 , Welch and Loscalzo 1998 ). Homocysteine is a sulfur-containing amino acid whose metabolism is at the intersection of two metabolic pathways: transsulfuration and remethylation. During transsulfuration, the enzyme cystathionine ß-synthase (CBS³ ) catalyzes an irreversible condensation of homocysteine and serine to cystathionine, using vitamin B-6 as a cofactor. In remethylation, the methyl donor for the conversion of homocysteine to methionine is provided by the reduction of 5,10-methylene- tetrahydrofolate to 5-methyl-tetrahydrofolate by the enzyme 5,10-methylenetetra- hydrofolate reductase (MTHFR). 5-Methyltetrahydrofolate, the predominant circulating form of folate, acts as the methyl donor for remethylation of homocysteine to methionine by the vitamin B-12–dependent enzyme methionine synthase. Low intracellular concentrations of homocysteine are maintained by transsulfuration to cysteine or by remethylations to methionine. While the transsulfuration pathway contributes primarily to the maintenance of normal postprandial homocysteine concentrations, the remethylation pathway maintains normal fasting concentrations (Mudd et al. 1989 , Rosenblatt 1995 ).

During the past two decades, a body of research has demonstrated an association between concentrations of plasma total homocysteine and various vascular diseases, including cerebral, coronary, peripheral and venous thrombosis (Bakker and Brandjes 1997 , den Heijer et al. 1996 , Mayer et al. 1996 , Selhub et al. 1996 ). Increased concentrations of plasma total homocysteine may result from deficiencies of vitamin B-12, folic acid or vitamin B-6 and from genetic defects, mainly in the two enzymes MTHFR and CBS (D'Angelo and Selhub, 1997 ). The MTHFR gene was mapped to chromosomal region 1p36.3. A common C to T transition at nucleotide 677 (C677T) of the MTHFR gene-coding sequence, leading to the substitution of alanine to valine residue at position 226 in the protein, was described (Frosst et al. 1995 ). The presence of this common mutation was shown to correlate with increased MTHFR thermolability and reduced specific activity. It was shown in most studies that homozygous (TT), mutant subjects had significantly elevated plasma total homocysteine concentrations, whereas the total homocysteine concentration in subjects without the mutation (CC) and in heterozygous (CT) subjects was indistinguishable (Engbersen et al. 1995 , Frosst et al. 1995 , Harmon et al. 1996 , Jacques et al. 1996 ). Some studies on a variety of ethnic populations have demonstrated an association between homozygosity for the MTHFR C677T mutation and increased risk of premature atherosclerosis, pregnancies complicated by neural tube defects, early pregnancy loss and venous thrombosis (Arruda et al. 1997 , Kang et al. 1991 , Nelen et al. 1998 , Van der Put et al. 1996 ). Other reports have shown little or no impact of the C677T MTHFR mutation on the risk of vascular disease (Abbate et al. 1998 , Brattstrom et al. 1998 , Kostulas et al. 1998 , Verhoef et al. 1997 ).

Recently, a second common mutation in the same gene was described (Van der Put et al. 1998 , Weisberg et al. 1998 ). In this new mutation, an A to C transition at nucleotide 1298 (A1298C) leads to a glutamate to alanine substitution in the MTHFR protein. The A1298C mutation, like the C677T mutation, results in a decrease in MTHFR activity that is more pronounced in the homozygous (CC) than in the heterozygous (AC) or normal (AA) states, and does not result in a thermolabile protein.

No studies to date have analyzed the allelic frequency of the recently described A1298C mutation in population groups other than the Dutch and French Canadians. We undertook the present study to determine the allele frequency of both point mutations in the MTHFR gene, the A1298C and the C677T, examining the effect of these MTHFR mutations on plasma total homocysteine concentrations, and to assess association with folate concentrations and standard cardiovascular risk factors in a Jerusalem cohort of Jewish men and women.

	METHODS

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Subjects.

We investigated 377 subjects, 190 men and 187 women, aged 32–95 y (mean age 56.8 ± 13 y), from the Jewish population of Jerusalem, recruited from previous participation in a cross-sectional study designed to examine risk factors for atherosclerosis and diabetes (Bar-On et al. 1992 ).

Trained interviewers administered a structured interview. Informed consent was obtained from all participants, and the study was approved by the ethics committee of the Israeli Ministry of Health.

Biochemical measurements.

Blood was drawn from fasting subjects and placed into plain vacutainers and tubes containing disodium EDTA for further analysis. After collection, samples were promptly centrifuged (3,000 x g, 10 min), and aliquots were stored at -80°C. Plasma total homocysteine, the sum of protein-bound and free homocysteine, was determined by a procedure modified from Araki and Sako (1987) . In our procedure, a 100-µL plasma sample was treated with tributylphosphine to reduce disulfide bonds, resulting in free homocysteine. After protein precipitation, the supernatant fraction was alkalinized and treated with a fluorescent probe (fluorobenzo-2-oxa-1,3-diazole-4-sulfomate). Total homocysteine was determined after reverse phase HPLC by using isocratic elution and fluorimetric detection. Plasma folate concentrations were determined by a microbial assay with the use of a 96-well plate and manganese supplementation, as described previously (Tamura et al. 1990 ).

Physical measurements.

Blood pressure was measured in the sitting position by using an ordinary, mercury sphygmomanometer on the right arm. Hypertension was defined as a systolic blood pressure of 140 + mm Hg and/or diastolic blood pressure of 90 + mm Hg. Body mass index (BMI, kg/m²) was used as an estimate of general body composition.

Genetic analysis.

Genomic DNA was prepared from peripheral blood, as described previously (Miller et al. 1988 ). The C677T mutation in the MTHFR gene was analyzed by polymerase chain reaction (PCR) of genomic DNA by using the following primer pairs: 5'-TGAAGGA GAAGGTGT CTGCGGGA-3' (exonic) and 5'-AGGACGGTGCGGTGAGAGTG-3' (intronic). DNA was amplified by using a PCR thermal cycler (Perkin-Elmer, Cetus, Norwalk, CT). PCR was carried out in a total volume of 50 µL containing 0.120 µmol of each primer/L, 200 mmol each dNTP/L, 10 mmol Tris-HCl/L (pH 8.3), 1.5 mmol MgCl₂/L, 50 mmol KCl /L and 1.25 U of Taq polymerase (Boehringer Mannheim, Mannheim, Germany) and template DNA. The reaction conditions were as follows: initial denaturation at 95°C for 15 min and 35 subsequent cycles of denaturation at 94°C for 60 s, annealing at 61°C for 60 s, and extension at 72°C for 2 min. PCR product (10 µL) was digested with 8 U HinfI (Gibco BRL, Paisley, Scotland) and 2 mL of buffer for HinfI for 12 h at 37°C. The C677T mutation abolishes a HinfI restriction site. Digestion of the 198 bp fragment of the 677CC genotype results in two fragments of 175 and 23 bp, whereas the 677 TT genotype results in one fragment of 175 bp. DNA fragments were separated by electrophoresis on a 2% agarose gel and visualized with ethidium bromide. The second A1298C mutation was also analyzed by PCR by using the following primer pairs: 5'-CTTT GGGGAGCTGAA GGACTACTAC-3' and 5'-CACTTTGTGACCATTCCG GTTTG-3'. The reaction mixture was the same as for the C677T mutation, plus 2 mmol MgCl₂/L. Conditions were: initial denaturation-annealing-extension at 95°C for 5 min, 55°C for 2 min, and 72°C for 2 min, followed by 35 cycles of denaturation at 95°C for 75 s, annealing at 55°C for 75 s, extension at 72°C for 90 s, and a final extension time of 6 min at 72°C. The amplified fragment of 163 bp was digested with MboII (MBI fermentas, Vilna, Lithuania). The A1298C mutation abolishes an MboII restriction site. Digestion of the 163-bp fragment of the 1298 AA genotype gives five fragments, of 56, 31, 30, 28 and 18 bp, whereas the 1298CC genotype results in four fragments, of 84, 31, 30 and 18 bp. The fragments were analyzed by 20% polyacrylamide gel electrophoresis and visualized with ethidium bromide.

Statistics.

Allele frequencies were calculated by allele counting. Concordance of genotype frequencies with Hardy-Weinberg equilibrium was tested by a ² goodness-of-fit test. The Hardy-Weinberg law (Hardy 1908 ) defines a simple relationship between the frequency of genes in the population and the frequency of genotypes (i.e., individuals). Under certain assumptions (e.g., random mating, no migration, no inbreeding, no selective survival among genotypes, and large population sizes), the expected frequencies of genotypes will be the same in all subsequent generations. It is, therefore, useful for estimating allele frequencies from the prevalence of Mendelian traits. One-way ANOVA was used to estimate the significant differences between the mean values of the different genotypes, followed by pair-wise tests. Regression analyses were then performed to simultaneously examine the multiple correlates of homocysteine. Total homocysteine was examined as a continuous, dependent variable, with sex introduced as categorical (dummy) variable, and age and folate variables introduced as continuous, independent variables. Each of the mutations was put into the regression as a categorical variable, and the extent to which the association between one mutation and total homocysteine was modified by the other mutation was tested by introducing interaction terms into the multivariate regression models.

	RESULTS

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At examination, 12.6% of the 377 participants (mean age 56.8 ± 13 y; range 32–95 y) had hypertension and 10.4% had total plasma cholesterol of 6 mmol/L or higher. The prevalence of obesity (BMI >30.0 kg/m²) in this community was 25.9%. None had a history of coronary heart disease, and all subjects had normal renal function. Because the trends were similar for both sexes, data were combined for the 187 females and 190 males in all statistical analysis.

The allele frequencies of the 1298 A to C transition and the 677 C to T in the MTHFR gene were 34.0 and 37.3%, respectively. The distribution of the three genotypes were consistent with Hardy-Weinberg equilibrium, indicating a high prevalence of homozygosity for both A1298C and C677T mutations in this population-based study (Table 1 ).

Sex, age and folate were significantly associated with plasma total homocysteine concentrations (Table 3 ). Total homocysteine concentrations were significantly higher among homozygotes (TT) with the C677T mutation compared to individuals having the 677CC genotype, which is consistent with most previous reports. However, when the A1298C mutation was introduced into the second, third and fourth models, this mutation had no independent effect on plasma total homocysteine concentrations. In the present study, we were unable to show any significant effect of either MTHFR mutation, A1298C or C677T, on various measured traits, such as hypertension, total cholesterol or BMI (Table 4 ).

	DISCUSSION

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The importance of the MTHFR enzyme for vascular function is obvious in light of the severe hereditary MTHFR deficiency associated with the rare but well-established homocystinuria syndromes—clinical conditions that include premature atherosclerosis, thrombosis and a range of neurological findings (Fenton and Rosenberg 1989 , Mudd et al. 1972 ). Several previous studies revealed that a very common mutation in the MTHFR gene C677T is related to mild homocysteinemia and might increase the risk for vascular occlusive pathology. However, other recent publications negate this relationship (Abbate et al. 1998 , Brattstrom et al. 1998 , Kostulas et al. 1998 , Verhoef et al. 1997 ).

In the current study, we determined the prevalence of a newly described mutation in the MTHFR gene A1298C (Van der Put et al. 1998 , Weisberg et al. 1998 ) and the already known C677T mutation in a Jewish cohort population and related it to total homocysteine and folate concentrations. In addition, we explored possible associations with established cardiovascular risk factors.

Our data demonstrated that the A1298C mutation is highly prevalent and similar in its frequency to the known C677T mutation. The allele frequency was 0.34 for the A1298C mutation and 0.37 for the C677T mutation. Neither mutation frequency differed significantly with age.

Because it was previously reported that both mutations reduced MTHFR enzyme activity, we hypothesized that the recently described A1298C mutation would be associated with increased plasma total homocysteine concentration in the population studied. However, this was not the case and on the contrary, significantly lower concentrations of plasma total homocysteine were observed in subjects with the 677CC/1298CC genotype, compared to subjects with a 677CC/1298AA genotype. Only individuals who were homozygous (TT) for the C677T mutation had significantly higher plasma total homocysteine concentrations, which is in accordance with what has been reported previously (Engbersen et al. 1995 , Frosst et al. 1995 , Harmon et al. 1996 , Jacques et al. 1996 ). In contrast to the report by Van der Put et al. (1998) , in the current study subjects who were double heterozygotes A1298C/C677T did not have significantly increased plasma total homocysteine concentration. Although this apparent discrepancy remains to be resolved, our working hypothesis is that because the A1298C mutation is located within the C-terminal regulatory domain of the MTHFR gene, while the C677T mutation is located within the gene catalytic domain, subjects with the A1298C mutation have reduced MTHFR enzyme activity, but to a lesser extent than those with the C677T mutation.

We assume that the two substitutions arose separately on an A1298/C677 haplotype, and, therefore, the C1298/T677 haplotype is very rare. Only one of 377 subjects exhibited this haplotype, and doubly homozygous individuals were not observed.

Conflicting data have appeared in the literature concerning the association of the C677T mutation and such known clinical risk factors for atherosclerosis as hypertension and body mass index. In this study no association was found between the C677T mutation, BMI, and hypertension, which is consistent with some reports, but not with others (Abbate et al. 1998 , Nakato et al. 1998 , Verhoeff et al. 1998 , Wilcken et al. 1996 ). However, to our knowledge, this is the first study to report a lack of association between plasma total cholesterol, BMI, hypertension and the recently described A1298C mutation.

In conclusion, our study showed that the A1298C MTHFR mutation is also common in the Jewish Israeli population. In contrast to the C677T MTHFR mutation, we found no evidence to suggest an association between this A1298C MTHFR mutation and elevated plasma total homocysteine concentrations. However, we did demonstrate that the A1298C mutation affects homocysteine metabolism because subjects with the 677CC/1298CC genotype had significantly lower total homocysteine concentrations.

Additional studies are required to determine the importance of the recently described A1298C mutation and the role of the 677CC/1298CC genotype in homocysteine metabolism and its association with occlusive vascular disease.

	FOOTNOTES

 
¹ This work was supported in part by a grant from the Israeli Ministry of Health to G. Friedman; federal funds from the U.S. Department of Agriculture, Agriculture Research Service, under contract number 53–3K06–01 to J. Selhub; and contributions to H. Bar-On from Mr. David Chase from Hartford, CT, and Karen and Edward Porter from Kansas City, MO.

³ Abbreviations used: BMI, body mass index; CBS, cystathionine ß-synthase; MTHFR, methylenetetrahydrofolate reductase; PCR, Polymerase chain reaction.

Manuscript received March 25, 1999. Initial review completed April 28, 1999. Revision accepted June 2, 1999.

	REFERENCES

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1. Abbate R., Sardi L., Pepe G., Marcucci R., Brunelli T., Prisco T., Prisco D., Fatini C., Capanni M., Simonetti L., Gensini F. G. The high prevalence of thermolabile 5–10 methylenetetrahydrofolate reductase (MTHFR) in Italians is not associated to an increased risk for coronary artery disease (CAD). Thromb. Haemost. 1998;79:727-730[Medline]

2. Araki A., Sako Y. Determination of free and total homocysteine in human plasma by high-performance liquid chromatography with fluorescence detection. J. Chromatogr. 1987;422:43-52[Medline]

3. Arruda V. R., von Zuben P. M., Chiparini L. C., Annichino-Bizzacchi J. M., Costa F. F. The mutation ala677val in the methylenetetrahydrofolate reductase gene: A risk factor for arterial disease and venous thrombosis. Thomb. Haemost. 1997;77:818-821[Medline]

4. Bakker R. C., Brandjes D. P. Hyperhomocysteinaemia and associated disease. Phan. World. Sci. 1997;19:126-132

5. Bar-On H., Friedlander Y., Kidron M., Kark J. D. Serum glucose and insulin characteristics and prevalence of diabetes mellitus and impaired glucose tolerance in the adult Jewish population of Jerusalem. Nutr. Metab. Cardiovasc. Dis. 1992;2:75-78

6. Berwanger C. S., Jeremy J. T., Stansby G. Homocysteine and vascular disease. Br. J. Surg. 1995;82:726-731[Medline]

7. Brattstrom L., Zhang Y., Hurtig M., Refsum H., Ostensson S., Fransson L., Jones K., Landgren F., Brudin L., Ueland P. M. A Common methylenetetrahydrofolate reductase gene mutation and longevity. Atherosclerosis 1998;141:315-319[Medline]

8. D'Angelo A., Selhub J. Homocysteine and thrombotic disease. Blood 1997;90:1-11[Free Full Text]

9. den Heiger M., Koster T., Blom H. J., Bos G.M.J., Briet E., Reitsma P. H., Vandenbroucke J. P., Rosendaal F. R. Hyperhomocysteinemia as a risk factor for deep-vein thrombosis. N. Engl. J. Med. 1996;334:759-762[Abstract/Free Full Text]

10. Engbersen A.M.T., Franken D. G., Boers G.H.J., Stevens E.M.B., Trijbels F. J. M., Blom H. J. Thermolabile 5,10-methylenetetrahydrofolate reductase as a cause of mild hyperhomocysteinemia. Am. J. Hum. Genet. 1995;56:142-150[Medline]

11. Fenton W. A., Rosenberg L. E. Inherited disorders of cobalamin transport and metabolism. Scriver C. R. Beaudet A. L. Sly W. S. Valle D. eds. The Metabolic Basis of Inherited Disease 1989:2065 McGraw-Hill New York, NY.

12. Frosst P., Blim H. J., Milos R., Goyette P., Sheppard C. A., Matthews R. G., Boers G.J.H., den Heijer M., Kluijtmans L.A.J., van den Heuvel L. P., Rozen R. A candidate genetic risk factor for vascular disease: A common mutation in methylenetetrahydrofolate reductase. Nat. Genet. 1995;10:111-113[Medline]

13. Glueck C. J., Shaw P., Lang J. E., Tracy T., Sieve-Smith L., Wang Y. Evidence that homocysteine is an independent risk factor for atherosclerosis in hyperlipidemic patients. Am. J. Cardiol. 1995;75:132-136[Medline]

14. Graeber J. E., Slott H. J., Ulane R. E., Schulman J. D., Stuart M. J. Effect of homocysteine on platelet and vascular arachidonic acid metabolism. Pediatr. Res. 1982;16:490-493[Medline]

15. Hardy G. H. Mendelian proportions in a mixed population. Science 1908;28:9-50

16. Harmon D. L., Woodside J. V., Yarnell J.W.G., McMaster D., Young I. S., McCrum E. E., Gey K. F., Whitehead A. S., Evans A. E. The common `thermolabile' variant of methylenetetrahydrofolate reductase is a major determinant of mild hyperhomocysteinemia. Q. J. Med. 1996;89:571-577[Abstract]

17. Heinecke J. W., Rosen H., Suzuki L. A., Chait A. The role of sulfur containing amino acids in superoxide production and modification of low density lipoprotein by arterial smooth muscle cells. J. Biol. Chem. 1987;262:10098-10103[Abstract/Free Full Text]

18. Jacques P. F., Bostom A. G., Williams R. G., Ellison R. C., Eckfeldt J. H., Rosenberg I. H., Selhub J., Rozen R. Relation between folate status, a common mutation in methylenetetrahydrofolate reductase, and plasma homocysteine concentrations. Circulation 1996;93:7-9[Abstract/Free Full Text]

19. Kang S. S., Wong P.W.K., Susmano A., Sora J., Norusis M., Russie N. Thermolabile methylenetetrahydrofolate reductase: An inherited risk factor for coronary artery disease. Am. J. Hum. Genet. 1991;48:536-545[Medline]

20. Kostulas K., Crisby M., Huang W. X., Lannfelt L., Hagenfeldt G., Eggertsen G., Kostulas V., and Hillert J. A methylenetetrahydrofolate reductase gene polymorphism in ischaemic stroke and in carotid artery stenosis. European J. Clin. Invest. 1998;28:285-289[Medline]

21. Mayer E. L., Jacobsen D. W., Robinson K. Homocysteine and coronary arteriosclerosis. J. Am. Coll. Card. 1996;27:517-527[Abstract]

22. McCully K. S., Carvalho A. C. Homocysteine thiolactone, N-homocysteine thiolactonyl retinamide, and platelet aggregation. Res. Commun. Chem. Pathol. Pharmacol. 1987;56:349-360[Medline]

23. Miller S. A., Dydes D. D., Polesky H. F. A simple salting out procedure for extracting DNA from human nucleated cells. Nucleic Acids Rec 1988;16:1215(abs.)

24. Mudd S. H., Levy H. L., Skovby F. Disorders of transsulfuration. Scriver C. R. Beaudet A. L. Sly W. S. Valle D. eds. The Metabolic Basis of Inherited Disease 1989:693-734 McGraw-Hill New York, NY.

25. Mudd S. H., Uhlendorf B. W., Freeman J. M., Findelstein J. D., Shih V. E. Homocystinuria associated with decreased methylenetetrahydrofolate reductase activity. Biochem. Biophys. Res. Commun. 1972;46:905(abs.)[Medline]

26. Nakato Y., Katsuya T., Takami S., Sato N., Fu Y., Ishikawa K., Takiuchi S., Rakugi H., Miki T., Higaki J., Ogihara T. Methylenetetrahydrofolate reductase gene polymorphism: Relation to blood pressure and cerebrovascular disease. Am. J. Hyperten. 1998;11:1019-1023[Medline]

27. Nelen W. L., Blom H. J., Thomas C. M., Steegers E. A., Boers G. H., Eskes T. K. Methylenetetrahydrofolate reductase polymorphism affects the change in homocysteine and folate concentrations resulting from low dose folic acid supplementation in women with unexplained recurrent miscarriages. J. Nutr. 1998;128:1336-1341[Abstract/Free Full Text]

28. Parthasarathy S. Oxidation of low density lipoproteins by thiol compounds leads to its recognition by the acetyl LDL receptor. Biochim. Biophys. Acta. 1987;917:337-340[Medline]

29. Rodgers G. M., Conn M. T. Homocysteine, an atherogenic stimulus, reduces protein C activation by arterial and venous endothelial cells. Blood 1990;75:895-901[Abstract/Free Full Text]

30. Rosenblatt D. S. Inherited disorders of folate transport and metabolism. Scriver C. R. Beaudet A. L. Sly W. S. Valle D. eds. The Metabolic and Molecular Basis of Inherited Disease 1995:3111-3128 McGraw-Hill New York, NY.

31. Selhub, J., Jacques, P. F., Bostom, A. D., D'Agostino, R. B., Wilson, P.W.F., Belanger, A. J., O'Leary, D. H., Wolf, P. A., Rush, D., Schaefer, E. J. & Rosenberg, I. H. (1996) Relationship between plasma homocysteine, vitamin status and extracranial carotid-artery stenosis in the Framingham Study population. Am. Inst. Nutr. 1258S–1265S.

32. Starkenbaum G., Harlan J. M. Endothelial cell injury due to copper-catalyzed hydrogen peroxide generation from homocysteine. J. Clin. Invest. 1986;77:1370-1376

33. Tamura T., Freeberg L. E., Cornwell P. E. Inhibition by EDTA of growth of lacto-bacillus casei in the folate microbiological assay and its reversal by added manganese or iron. Clin. Chem. 1990;36:1993(abs.)[Medline]

34. Van der Put N.M.J., Gabreels F., Stevens E.M.B., Smeitink J.A.M., Trijbels F.J.M., Eskes T.K.A.B., van den Heuvel L. P., Blom H. J. A second common mutation in the methylenetetrahydrofolate reductase gene: An additional risk factor for neural-tube defects?. Am. J. Hum. Genet. 1998;62:1044-1051[Medline]

35. Van der Put N.M.J., van den Heuvel L. P., Steegers-Theunissen P.R.M., Trijbels F.J.M., Eskes T.K.A.B., Mariman E.C.M., den Heyer M., Blom H. J. Decreased methylene-tetrahydrofolate reductase function due to the 677CT mutation in families with spina bifida offspring. J. Mol. Med. 1996;74:691-694[Medline]

36. Verhoef P., Kok F. J., Klluijtmans L. A., Blom H. J., Refsum H., Ueland P. M., Kruyssen D. A. The 677CT mutation in themethylenetetrahydrofolate reductase gene: Associations with plasma total homocyeine levels and risk of coronary atherosclerotic disease. Atherosclerosis 1997;132:105-113[Medline]

37. Verhoeff B. J., Trip M. D., Prins M. H., Kastelein J.J.P., Reitsma P. H. The effect of a common methylenetetrahydrolate reductase mutation on levels of homocysteine, folate, vitamin B12 and on the risk of premature atherosclerosis. Atherosclerosis 1998;141:161-166[Medline]

38. Weisberg I., Tran P., Christensen B., Sibani S., Rozen R. A second genetic polymorphism in methylenetetrahydrofolate reductase (MTHFR) associated with decreased enzyme activity. Molec. Genet. Metabolism. 1998;64:169-172

39. Welch G. N., Loscalzo J. Homocysteine and atherothrombosis. N. Engl. J. Med. 1998;338:1042-1050[Free Full Text]

40. Wilcken D.E.L., Wang X. L., Sim A. S., McCredie M. Distribution in healthy and coronary populations of the methylenetetrahydrofolate reductase (MTHFR) C677T mutation. Arterioscler. Thromb. Vasc. Biol. 1996;16:878-882[Abstract/Free Full Text]

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				S. Friso, D. Girelli, E. Trabetti, O. Olivieri, P. Guarini, P. F. Pignatti, R. Corrocher, and S.-W. Choi The MTHFR 1298A>C Polymorphism and Genomic DNA Methylation in Human Lymphocytes Cancer Epidemiol. Biomarkers Prev., April 1, 2005; 14(4): 938 - 943. [Abstract] [Full Text] [PDF]

				K. Robien, C. M. Ulrich, J. Bigler, Y. Yasui, T. Gooley, B. Bruemmer, J. D. Potter, and J. P. Radich Methylenetetrahydrofolate Reductase Genotype Affects Risk of Relapse after Hematopoietic Cell Transplantation for Chronic Myelogenous Leukemia Clin. Cancer Res., November 15, 2004; 10(22): 7592 - 7598. [Abstract] [Full Text] [PDF]

				Y Berkun, D Levartovsky, A Rubinow, H Orbach, S Aamar, T Grenader, I Abou Atta, D Mevorach, G Friedman, and A Ben-Yehuda Methotrexate related adverse effects in patients with rheumatoid arthritis are associated with the A1298C polymorphism of the MTHFR gene Ann Rheum Dis, October 1, 2004; 63(10): 1227 - 1231. [Abstract] [Full Text] [PDF]

				S. Narayanan, J. McConnell, J. Little, L. Sharp, C. J. Piyathilake, H. Powers, G. Basten, and S. J. Duthie Associations between Two Common Variants C677T and A1298C in the Methylenetetrahydrofolate Reductase Gene and Measures of Folate Metabolism and DNA Stability (Strand Breaks, Misincorporated Uracil, and DNA Methylation Status) in Human Lymphocytes In vivo Cancer Epidemiol. Biomarkers Prev., September 1, 2004; 13(9): 1436 - 1443. [Abstract] [Full Text] [PDF]

				M. S. Cicek, N. L. Nock, L. Li, D. V. Conti, G. Casey, and J. S. Witte Relationship between Methylenetetrahydrofolate Reductase C677T and A1298C Genotypes and Haplotypes and Prostate Cancer Risk and Aggressiveness Cancer Epidemiol. Biomarkers Prev., August 1, 2004; 13(8): 1331 - 1336. [Abstract] [Full Text] [PDF]

				R Castro, I Rivera, P Ravasco, M E Camilo, C Jakobs, H J Blom, and I T de Almeida 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C->T and 1298A->C mutations are associated with DNA hypomethylation J. Med. Genet., June 1, 2004; 41(6): 454 - 458. [Full Text] [PDF]

				L. Sharp and J. Little Polymorphisms in Genes Involved in Folate Metabolism and Colorectal Neoplasia: A HuGE Review Am. J. Epidemiol., March 1, 2004; 159(5): 423 - 443. [Abstract] [Full Text] [PDF]

				M. Krajinovic, S. Lamothe, D. Labuda, E. Lemieux-Blanchard, Y. Theoret, A. Moghrabi, and D. Sinnett Role of MTHFR genetic polymorphisms in the susceptibility to childhood acute lymphoblastic leukemia Blood, January 1, 2004; 103(1): 252 - 257. [Abstract] [Full Text] [PDF]

				J. Little, L. Sharp, S. Duthie, and S. Narayanan Colon Cancer and Genetic Variation in Folate Metabolism: The Clinical Bottom Line J. Nutr., November 1, 2003; 133(11): 3758S - 3766. [Abstract] [Full Text] [PDF]

				E. Giovannucci, J. Chen, S. A. Smith-Warner, E. B. Rimm, C. S. Fuchs, C. Palomeque, W. C. Willett, and D. J. Hunter Methylenetetrahydrofolate Reductase, Alcohol Dehydrogenase, Diet, and Risk of Colorectal Adenomas Cancer Epidemiol. Biomarkers Prev., October 1, 2003; 12(10): 970 - 979. [Abstract] [Full Text] [PDF]

				R. Castro, I. Rivera, P. Ravasco, C. Jakobs, H.J. Blom, M.E. Camilo, and I.T. de Almeida 5,10-Methylenetetrahydrofolate reductase 677C->T and 1298A->C mutations are genetic determinants of elevated homocysteine QJM, April 1, 2003; 96(4): 297 - 303. [Abstract] [Full Text] [PDF]

				K. Robien and C. M. Ulrich 5,10-Methylenetetrahydrofolate Reductase Polymorphisms and Leukemia Risk: A HuGE Minireview Am. J. Epidemiol., April 1, 2003; 157(7): 571 - 582. [Abstract] [Full Text] [PDF]

				V. Shpichinetsky, I. Raz, Y. Friedlander, N. Goldschmidt, I. D. Wexler, A. Ben-Yehuda, and G. Friedman The Association between Two Common Mutations C677T and A1298C in Human Methylenetetrahydrofolate Reductase Gene and the Risk for Diabetic Nephropathy in Type II Diabetic Patients J. Nutr., October 1, 2000; 130(10): 2493 - 2497. [Abstract] [Full Text]

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