Skip to main content

Methylenetetrahydrofolate reductase and transcobalamin genetic polymorphisms in human spontaneous abortion: biological and clinical implications


The pathogenesis of human spontaneous abortion involves a complex interaction of several genetic and environmental factors. The firm association between increased homocysteine concentration and neural tube defects (NTD) has led to the hypothesis that high concentrations of homocysteine might be embryotoxic and lead to decreased fetal viability. There are several genetic polymorphisms that are associated with defects in folate- and vitamin B12-dependent homocysteine metabolism. The methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C polymorphisms cause elevated homocysteine concentration and are associated with an increased risk of NTD. Additionally, low concentration of vitamin B12 (cobalamin) or transcobalamin that delivers vitamin B12 to the cells of the body leads to hyperhomocysteinemia and is associated with NTD. This effect involves the transcobalamin (TC) 776C>G polymorphism. Importantly, the biochemical consequences of these polymorphisms can be modified by folate and vitamin B12 supplementation. In this review, I focus on recent studies on the role of hyperhomocysteinemia-associated polymorphisms in the pathogenesis of human spontaneous abortion and discuss the possibility that periconceptional supplementation with folate and vitamin B12 might lower the incidence of miscarriage in women planning a pregnancy.

Homocysteine metabolism and genetic polymorphisms – an overview

Accumulating evidence suggest that the sulfur-containing amino acid homocysteine plays a role in various developmental disorders [1]. Two main factors affect homocysteine concentration in humans: diet (mainly intake of folate and vitamin B12) and polymorphisms in genes that encode enzymes or transport proteins involved in folate- and vitamin B12-dependent homocysteine metabolism, the so called one-carbon metabolism, which is a complex series of metabolic pathways crucial for DNA synthesis and repair and a wide range of methylation reactions (Fig. 1).

Figure 1

Overview of the human folate- and vitamin B12-dependent homocysteine metabolism indicating its one-carbon donors and acceptors involved in methyl group biogenesis and DNA synthesis. MTHFR, methylenetetrahydrofolate reductase; MSR, methionine synthase reductase; dUMP, deoxyuridylate; dTMP, deoxythymidylate.

Methylenetetrahydrofolate reductase (MTHFR, EC is a key enzyme in one-carbon metabolism. The enzyme catalyzes the conversion of 5,10-methylenetetrahydrofolate into 5-methyltetrahydrofolate, the predominating circulating form of folate. 5-methyltetrahydrofolate participates in the vitamin B12-dependent remethylation of homocysteine to methionine that is converted to S-adenosylmethionine that serves as a methyl group donor in the methylation of DNA, proteins, neurotransmitters and phospholipids [2]. MTHFR gene polymorphisms are commonly associated with hyperhomocysteinemia [3, 4]. In pregnant women this is a risk factor for neural tube defects (NTD) [5, 6] and recurrent embryo loss [79] as discussed thoroughly in three recent reviews [1012]. Recently, Gris et al. also reported an association between increased levels of homocysteine and a first early pregnancy loss [13]. The best characterized MTHFR genetic polymorphism consists of a 677C>T transition which results in an alanine to valine substitution in the predicted catalytic domain of MTHFR [3]. This substitution renders the enzyme thermolabile, and homozygotes and heterozygotes have about a 70% and 35% reduced MTHFR activity in vitro, respectively. Homozygosity for the 677T allele is associated with elevated homocysteine levels, predominantly in individuals who have a low plasma folate level [14]. Furthermore, the level of plasma homocysteine can be lowered in homozygous individuals by folate supplementation [15]. About half the general population carries at least one mutated allele and the frequency of the homozygous mutated genotype (677TT) ranges from 1 to 20% depending on the population [16]. A second common polymorphism in the MTHFR gene is a 1298A>C transition which results in a glutamate to alanine substitution within a presumed regulatory domain of MTHFR [4, 17]. The 1298C allele has been reported to lead to decreased enzyme activity, although not to the same extent as the 677T allele [4, 17, 18]. Individuals who are compound heterozygous for the 677T and 1298C alleles, which produces a 677CT/1298AC genotype, have according to some studies 40–50% reduced MTHFR activity in vitro and a biochemical profile similar to that seen among 677T homozygotes with increased homocysteine levels and decreased folate levels [4, 17]. However, recent results indicate that the MTHFR 1298A>C polymorphism does not contribute significantly to hyperhomocysteinemia, neither by itself nor in combination with the 677C>T polymorphism [19, 20], and the phenotypic effect of the polymorphism has also been questioned from a biochemical point of view [21]. It must, however, be borne in mind that the absence of a biochemical phenotype in vitro does not necessarily rule out the possible importance of the 1298A>C polymorphism in vivo, for instance during times of high folate requirement, such as pregnancy [22].

Yet another common genetic polymorphism that influences homocysteine concentration is a C>G transition at position 776 (776C>G) in the transcobalamin (TC) gene [23]. The transition results in a substitution of arginine for proline at codon 259 and is the major determinant of the TC phenotypic variability in Caucasian populations [24, 25]. TC is the critical transporter that delivers vitamin B12 to peripheral tissues and heterozygosity for the polymorphism has been associated with hyperhomocysteinemia [25]. The wild-type 776C allele has positive effects on TC plasma levels [2527], which may be important for efficient vitamin B12 delivery to the cells of the growing embryo.

Folate, vitamin B12 and homocysteine in embryonic development

One-carbon metabolism during embryonic development has been studied mostly with regard to the development of the nervous system. Pregnant women who are folate deficient have a greatly increased risk of NTD in their babies and periconceptional folate supplementation protects against this effect [12, 2831]. The molecular events that lead to NTD due to folate deficiency are not known but may include insufficient methylation of crucial metabolites in the developing embryo and/or abnormalities in neural cell proliferation, differentiation and apoptosis, which may be due to DNA nucleotide misincorporation that accompanies folate deficiency in proliferating cells [2]. It seems likely that these fundamental events also might lead to decreased fetal viability. In agreement with this view, a recent population-based case-control study showed an increased risk of early spontaneous abortion among pregnant women with low plasma folate levels [32]. Vitamin B12 deficiency during pregnancy results in elevated homocysteine concentration in the embryo and increases the incidence of NTD [26, 31, 33, 34]. In addition, hereditary deficiency of transcobalamin results in profound neurological abnormalities and mental retardation [35]. Three studies envisage a direct embryotoxic effect of homocysteine [3638]. In one study exposure of chick embryos to homocysteine resulted in defects both of the heart and the neural tube [36], while exposure of mouse and rat embryos to homocysteine in two other studies mainly resulted in growth retardation and abnormalities of somite development, but not in neurulation defects or other teratogenic effects [37, 38]. The precise mechanism of homocysteine toxicity remains elusive but there are several hypotheses, some of which have been tested experimentally. The toxic effect of homocysteine in developing rat embryos may result from increased formation of S-adenosylhomocysteine that could inhibit critical methylation reactions [38]. Elevated homocysteine concentration could also inhibit de novo synthesis of deoxythymidylate (dTMP). Exposure of proliferating B-lymphoid Raji cells to excess homocysteine or methionine increases the uptake of exogenous thymidine owing to inhibition of the thymidylate synthase-catalyzed reaction in which deoxyuridylate (dUMP) is converted to dTMP (Fig. 1) [39]. It is thought that 5,10-methylenetetrahydrofolate, a cofactor in this reaction, is depleted in the presence of excess homocysteine due to increased demand for 5-methyltetrahydrofolate to remove homocysteine by methylation. This might induce DNA damage through increased misincorporation of dUMP in place of dTMP in DNA followed by excision-repair reactions, DNA strand breaks, cell-cycle arrest and, ultimately, apoptosis. In conclusion, folate, vitamin B12 and homocysteine play several fundamental roles in growing cells and thus in the developing embryo. It is also possible that homocysteine by itself induces some of the developmental disorders previously attributed to folate and/or vitamin B12 deficiency.

MTHFR and TC genetic polymorphisms in human spontaneous abortion

Through their defects in folate- and vitamin B12-dependent homocysteine metabolism, MTHFR and TC polymorphisms have been implicated as risk factors for several developmental disorders, such as NTD [4044], orofacial clefting [45] and Down syndrome [46], although there are studies failing to replicate these findings [4751]. Interestingly, Wenstrom et al. found a strong association between fetal MTHFR 677T alleles, elevated homocysteine concentration in amniotic fluid and neurotubular defects spanning the cervical-lumbar spine, lumbosacral spine, and occipital encephalocele, but not anencephaly, exencephaly or spina bifida confined to the sacrum [52]. The authors conclude that the MTHFR 677T allele predisposes only to certain types of NTD [52].

As mentioned earlier, maternal hyperhomocysteinemia is a risk factor for recurrent embryo loss [79] and also for a first early embryo loss [13]. In addition to these findings, some studies have reported an association between maternal MTHFR 677T alleles and increased risk of recurrent spontaneous abortion [5356] (Table 1). However, this effect has not been replicated in other studies [5763]. Likewise, six studies found no association between maternal 677T alleles and non-recurrent fetal loss [61, 6468], but five of these only examined late fetal loss (fetal death after 19 weeks or more of gestation). Aside from strong bias toward late-pregnancy outcomes and nutritional and ethnic differences between the study populations, one explanation for the discrepant results may be that the numbers of study participants have been relatively small, yielding a low power, i.e. a low probability for detecting a difference if there is one. It is also possible that fetal genotypes would have produced clearer results. The common effects of MTHFR and TC mutated alleles are lower bioavailability of folate and vitamin B12 and increased homocysteine concentration. Since vital cellular processes such as proliferation and differentiation are dependent on folate- and vitamin B12-mediated one-carbon metabolism, these effects may be especially pronounced early in embryogenesis when the cells undergo rapid proliferation and differentiation [12]. Hence, it would be of special interest to analyze spontaneously aborted embryos, not just the mothers, for the MTHFR and TC polymorphisms. Recently, four studies addressing this issue were undertaken [22, 6971] (Table 1). Isotalo et al. reported high prevalence of mutated MTHFR alleles in aborted embryos [69]. However, their study group consisted of fetal tissue samples from both spontaneous and therapeutic terminations of pregnancy, which diminishes the interpretability of the investigation. We undertook a similar study, except that only spontaneously aborted embryos (fetal death between sixth and twentieth week after conception) were included. There was a significant odds ratio for spontaneous abortion of 14.2 (95% CI 1.78–113; p = 0.001) when comparing the prevalence of one or more 677T and 1298C alleles versus the wild type combined genotype (677CC/1298AA) in cases and controls, indicating that the MTHFR polymorphisms may have a major impact on fetal survival [22]. The prevalence of the mutated TC 776G allele was significantly increased in aborted embryos while the frequency of wild-type TC 776C homozygotes was much lower among spontaneously aborted embryos than controls (9.1% and 32.2%, respectively; p < 0.001) [70]. These data are consistent with the view that the 776C allele may have beneficial influences during embryogenesis, conceivably through its positive effect on vitamin B12 intracellular bioavailability, which among other things results in reduced homocysteine concentration. Finally, we addressed the possibility of a gene-gene interaction between the MTHFR and TC polymorphisms in human spontaneous abortion [71]. Embryos that had combined MTHFR 677TT and TC 776CG or 776GG genotypes; genotypes that individually are associated with impaired homocysteine metabolism in adults, were at increased risk for spontaneous abortion compared to embryos that had only one of these genotypes. This indicates a detrimental interaction between the hyperhomocysteinemia-associated MTHFR 677TT and TC 776CG or 776GG genotypes during embryogenesis and further underscores the linkage between decreased fetal viability and elevated homocysteine concentration. Other candidate gene-gene interactions that remain to be explored in spontaneous abortion are between the MTHFR and TC genes and the genes for cystathionine β-synthase [72], methionine synthase [42] and methionine synthase reductase [73], which all are involved in one-carbon metabolism and have been examined in relation to NTD.

Table 1 Maternal and fetal MTHFR 677T alleles in human spontaneous abortion.

Another possible, but as yet unexplored, type of genetic interaction in human spontaneous abortion is a maternal-fetal interaction. The 677C>T polymorphism confers an even higher risk for NTD if both the mother and her child are homozygous for the 677T allele, as compared to if only the mother or the child is homozygous [42]. Conceivably, the homocysteine concentration in the embryo would be even higher if both the mother and the embryo carried hyperhomocysteinemia-associated MTHFR and TC genotypes and, if the hypothesis of the embryotoxicity of homocysteine were true, this would lead to even further increased risk of spontaneous abortion.

Prevention of human spontaneous abortion by periconceptional B-vitamin supplementation

The MTHFR and TC polymorphisms are modifiable genetic risk factors. Increased intake of folate [15] and vitamin B12 (Zetterberg et al., unpublished data) neutralizes the negative effects of the mutated alleles on homocysteine metabolism. The effect of folate supplementation on prevention of NTD has been questioned [74], but generally it appears that daily consumption of 400 μg of folate before conception and during early pregnancy reduces the occurrence of NTD [29, 30]. Moreover, the impact of mandatory fortification of grain with folate on the prevention of NTD was recently documented in the United States where a 19% reduction in NTD birth prevalence was seen following folate food fortification, although factors other than fortification may have contributed to this decline [75]. It has been suggested that the probable reduction in risk of pregnancy complications may be more effective if a combination of folate and vitamin B12 is given [31, 76]. Hence, pregnant women that carry hyperhomocysteinemia-associated MTHFR and TC genotypes might benefit from supplementation with both folate and vitamin B12 to reduce the risk of miscarriage. Since the MTHFR and TC polymorphisms are very common, and since the data indicate that the fetal genotype is as important as the maternal genotype, a general recommendation of periconceptional supplementation with folate and vitamin B12 may be considered. It should, however, be remembered that certain populations already have adequate intake of folate and vitamin B12 even for carriers of variant alleles. For instance traditional Mediterranean diet is abundant in folate [77, 78].

Can periconceptional B-vitamin supplementation lead to any adverse effects? There is evidence for an increase in twinning frequency with increased risk of pregnancy complications following folate supplementation [79, 80]. Moreover, a case-control study investigated the 677C>T polymorphism in mothers with dichorionic twin pregnancies and found a lower frequency of the 677T allele amongst mothers of twins compared with women who gave birth to singletons [81]. The authors suggest that the MTHFR 677T allele is protective against multiple pregnancies and that folate supplementation might increase the risk of twinning. However, recent results from a large population-based cohort study in China showed no evidence for effects of folate supplementation on twinning frequency [82]. Likewise, there was no evidence for association between MTHFR genotype and twinning in mothers of twins or for the loss of specific MTHFR genotypes during twin pregnancies in a very recent large study of families with twins and of twin pairs [83]. Lastly, there has been some concern that folate supplements might increase abortion rates by delaying very early abortions that would not have been recognized as a pregnancy in the absence of vitamin supplementation [84, 85], but a large population-based case-control study revealed no association between high folate levels and increased risk of spontaneous abortion [32]. In fact, a non-significant trend toward a protective effect associated with high folate levels was seen.

Taken together, the data reviewed in this article warrant additional investigations exploring the potential beneficial effects of periconceptional supplementation with both folate and vitamin B12 in the prevention of spontaneous abortion.


  1. 1.

    Johnson WG: Teratogenic alleles and neurodevelopmental disorders. Bioessays. 2003, 25: 464-477. 10.1002/bies.10268.

    CAS  Article  PubMed  Google Scholar 

  2. 2.

    Mattson MP, Shea TB: Folate and homocysteine metabolism in neural plasticity and neurodegenerative disorders. Trends Neurosci. 2003, 26: 137-146. 10.1016/S0166-2236(03)00032-8.

    CAS  Article  PubMed  Google Scholar 

  3. 3.

    Frosst P, Blom HJ, Milos R, Goyette P, Sheppard CA, Matthews RG, Boers GJ, den Heijer M, Kluijtmans LA, van den Heuvel LP, et al.: A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase. Nat Genet. 1995, 10: 111-113.

    CAS  Article  PubMed  Google Scholar 

  4. 4.

    van der Put NM, Gabreels F, Stevens EM, Smeitink JA, Trijbels FJ, Eskes TK, van den Heuvel LP, Blom HJ: 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. 10.1086/301825.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  5. 5.

    Steegers-Theunissen RP, Boers GH, Trijbels FJ, Eskes TK: Neural-tube defects and derangement of homocysteine metabolism. N Engl J Med. 1991, 324: 199-200.

    CAS  Article  PubMed  Google Scholar 

  6. 6.

    Mills JL, McPartlin JM, Kirke PN, Lee YJ, Conley MR, Weir DG, Scott JM: Homocysteine metabolism in pregnancies complicated by neural-tube defects. Lancet. 1995, 345: 149-151. 10.1016/S0140-6736(95)90165-5.

    CAS  Article  PubMed  Google Scholar 

  7. 7.

    Steegers-Theunissen RP, Boers GH, Blom HJ, Trijbels FJ, Eskes TK: Hyperhomocysteinaemia and recurrent spontaneous abortion or abruptio placentae. Lancet. 1992, 339: 1122-1123. 10.1016/0140-6736(92)90725-I.

    CAS  Article  PubMed  Google Scholar 

  8. 8.

    Wouters MG, Boers GH, Blom HJ, Trijbels FJ, Thomas CM, Borm GF, Steegers-Theunissen RP, Eskes TK: Hyperhomocysteinemia: a risk factor in women with unexplained recurrent early pregnancy loss. Fertil Steril. 1993, 60: 820-825.

    CAS  PubMed  Google Scholar 

  9. 9.

    Nelen WL, Blom HJ, Steegers EA, den Heijer M, Eskes TK: Hyperhomocysteinemia and recurrent early pregnancy loss: a meta-analysis. Fertil Steril. 2000, 74: 1196-1199. 10.1016/S0015-0282(00)01595-8.

    CAS  Article  PubMed  Google Scholar 

  10. 10.

    de la Calle M, Usandizaga R, Sancha M, Magdaleno F, Herranz A, Cabrillo E: Homocysteine, folic acid and B-group vitamins in obstetrics and gynaecology. Eur J Obstet Gynecol Reprod Biol. 2003, 107: 125-134. 10.1016/S0301-2115(02)00305-6.

    CAS  Article  PubMed  Google Scholar 

  11. 11.

    Nelen WL: Hyperhomocysteinaemia and human reproduction. Clin Chem Lab Med. 2001, 39: 758-763.

    CAS  Article  PubMed  Google Scholar 

  12. 12.

    van der Put NM, van Straaten HW, Trijbels FJ, Blom HJ: Folate, homocysteine and neural tube defects: an overview. Exp Biol Med (Maywood). 2001, 226: 243-270.

    CAS  Google Scholar 

  13. 13.

    Gris JC, Perneger TV, Quere I, Mercier E, Fabbro-Peray P, Lavigne-Lissalde G, Hoffet M, Dechaud H, Boyer JC, Ripart-Neveu S, Tailland ML, Daures JP, Mares P, Dauzat M: Antiphospholipid/antiprotein antibodies, hemostasis-related autoantibodies, and plasma homocysteine as risk factors for a first early pregnancy loss: a matched case-control study. Blood. 2003, 102: 3504-3513. 10.1182/blood-2003-01-0320.

    CAS  Article  PubMed  Google Scholar 

  14. 14.

    Jacques PF, Bostom AG, Williams RR, Ellison RC, Eckfeldt JH, Rosenberg IH, Selhub J, Rozen R: Relation between folate status, a common mutation in methylenetetrahydrofolate reductase, and plasma homocysteine concentrations. Circulation. 1996, 93: 7-9.

    CAS  Article  PubMed  Google Scholar 

  15. 15.

    Malinow MR, Nieto FJ, Kruger WD, Duell PB, Hess DL, Gluckman RA, Block PC, Holzgang CR, Anderson PH, Seltzer D, Upson B, Lin QR: The effects of folic acid supplementation on plasma total homocysteine are modulated by multivitamin use and methylenetetrahydrofolate reductase genotypes. Arterioscler Thromb Vasc Biol. 1997, 17: 1157-1162.

    CAS  Article  PubMed  Google Scholar 

  16. 16.

    Botto LD, Yang Q: 5,10-Methylenetetrahydrofolate reductase gene variants and congenital anomalies: a HuGE review. Am J Epidemiol. 2000, 151: 862-877.

    CAS  Article  PubMed  Google Scholar 

  17. 17.

    Weisberg I, Tran P, Christensen B, Sibani S, Rozen R: A second genetic polymorphism in methylenetetrahydrofolate reductase (MTHFR) associated with decreased enzyme activity. Mol Genet Metab. 1998, 64: 169-172. 10.1006/mgme.1998.2714.

    CAS  Article  PubMed  Google Scholar 

  18. 18.

    Chango A, Boisson F, Barbe F, Quilliot D, Droesch S, Pfister M, Fillon-Emery N, Lambert D, Fremont S, Rosenblatt DS, Nicolas JP: The effect of 677C-->T and 1298A-->C mutations on plasma homocysteine and 5,10-methylenetetrahydrofolate reductase activity in healthy subjects. Br J Nutr. 2000, 83: 593-596.

    CAS  Article  PubMed  Google Scholar 

  19. 19.

    Friso S, Girelli D, Trabetti E, Stranieri C, Olivieri O, Tinazzi E, Martinelli N, Faccini G, Pignatti PF, Corrocher R: A1298C methylenetetrahydrofolate reductase mutation and coronary artery disease: relationships with C677T polymorphism and homocysteine/folate metabolism. Clin Exp Med. 2002, 2: 7-12. 10.1007/s102380200001.

    CAS  Article  PubMed  Google Scholar 

  20. 20.

    Zetterberg H, Coppola A, D'Angelo A, Palmer M, Rymo L, Blennow K: No association between the MTHFR A1298C and transcobalamin C776G genetic polymorphisms and hyperhomocysteinemia in thrombotic disease. Thromb Res. 2002, 108: 127-131. 10.1016/S0049-3848(03)00004-5.

    CAS  Article  PubMed  Google Scholar 

  21. 21.

    Yamada K, Chen Z, Rozen R, Matthews RG: Effects of common polymorphisms on the properties of recombinant human methylenetetrahydrofolate reductase. Proc Natl Acad Sci U S A. 2001, 98: 14853-14858. 10.1073/pnas.261469998.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  22. 22.

    Zetterberg H, Regland B, Palmer M, Ricksten A, Palmqvist L, Rymo L, Arvanitis DA, Spandidos DA, Blennow K: Increased frequency of combined methylenetetrahydrofolate reductase C677T and A1298C mutated alleles in spontaneously aborted embryos. Eur J Hum Genet. 2002, 10: 113-118. 10.1038/sj.ejhg.5200767.

    CAS  Article  PubMed  Google Scholar 

  23. 23.

    Zetterberg H, Palmer M, Borestrom C, Rymo L, Blennow K: The transcobalamin codon 259 polymorphism should be designated 776C>G, not 775G>C. Blood. 2003, 101: 3749-50; author reply 3750-1. 10.1182/blood-2003-01-0084.

    Article  PubMed  Google Scholar 

  24. 24.

    McCaddon A, Blennow K, Hudson P, Regland B, Hill D: Transcobalamin polymorphism and homocysteine. Blood. 2001, 98: 3497-3499. 10.1182/blood.V98.12.3497.

    CAS  Article  PubMed  Google Scholar 

  25. 25.

    Namour F, Olivier J, Abdelmouttaleb I, Adjalla C, Debard R, Salvat C, Gueant J: Transcobalamin codon 259 polymorphism in HT-29 and Caco-2 cells and in Caucasians: relation to transcobalamin and homocysteine concentration in blood. Blood. 2001, 97: 1092-1098. 10.1182/blood.V97.4.1092.

    CAS  Article  PubMed  Google Scholar 

  26. 26.

    Afman LA, Van Der Put NM, Thomas CM, Trijbels JM, Blom HJ: Reduced vitamin B12 binding by transcobalamin II increases the risk of neural tube defects. Qjm. 2001, 94: 159-166. 10.1093/qjmed/94.3.159.

    CAS  Article  PubMed  Google Scholar 

  27. 27.

    Zetterberg H, Nexo E, Regland B, Minthon L, Boson R, Palmer M, Rymo L, Blennow K: The transcobalamin (TC) codon 259 genetic polymorphism influences holo-TC concentration in cerebrospinal fluid from patients with Alzheimer disease. Clin Chem. 2003, 49: 1195-1198. 10.1373/49.7.1195.

    CAS  Article  PubMed  Google Scholar 

  28. 28.

    Smithells RW, Sheppard S, Schorah CJ: Vitamin dificiencies and neural tube defects. Arch Dis Child. 1976, 51: 944-950.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  29. 29.

    Group MRC Vitamin Study Research: Prevention of neural tube defects. Lancet. 1991, 338: 131-137. 10.1016/0140-6736(91)90133-A.

    Article  Google Scholar 

  30. 30.

    Czeizel AE, Dudas I: Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med. 1992, 327: 1832-1835.

    CAS  Article  PubMed  Google Scholar 

  31. 31.

    Kirke PN, Molloy AM, Daly LE, Burke H, Weir DG, Scott JM: Maternal plasma folate and vitamin B12 are independent risk factors for neural tube defects. Q J Med. 1993, 86: 703-708.

    CAS  PubMed  Google Scholar 

  32. 32.

    George L, Mills JL, Johansson AL, Nordmark A, Olander B, Granath F, Cnattingius S: Plasma folate levels and risk of spontaneous abortion. Jama. 2002, 288: 1867-1873. 10.1001/jama.288.15.1867.

    CAS  Article  PubMed  Google Scholar 

  33. 33.

    van der Put NM, Thomas CM, Eskes TK, Trijbels FJ, Steegers-Theunissen RP, Mariman EC, De Graaf-Hess A, Smeitink JA, Blom HJ: Altered folate and vitamin B12 metabolism in families with spina bifida offspring. Qjm. 1997, 90: 505-510. 10.1093/qjmed/90.8.505.

    CAS  Article  PubMed  Google Scholar 

  34. 34.

    Steen MT, Boddie AM, Fisher AJ, Macmahon W, Saxe D, Sullivan KM, Dembure PP, Elsas LJ: Neural-tube defects are associated with low concentrations of cobalamin (vitamin B12) in amniotic fluid. Prenat Diagn. 1998, 18: 545-555. 10.1002/(SICI)1097-0223(199806)18:6<545::AID-PD293>3.3.CO;2-U.

    CAS  Article  PubMed  Google Scholar 

  35. 35.

    Thomas PK, Hoffbrand AV, Smith IS: Neurological involvement in hereditary transcobalamin II deficiency. J Neurol Neurosurg Psychiatry. 1982, 45: 74-77.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  36. 36.

    Rosenquist TH, Ratashak SA, Selhub J: Homocysteine induces congenital defects of the heart and neural tube: effect of folic acid. Proc Natl Acad Sci U S A. 1996, 93: 15227-15232. 10.1073/pnas.93.26.15227.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  37. 37.

    Greene ND, Dunlevy LE, Copp AJ: Homocysteine is embryotoxic but does not cause neural tube defects in mouse embryos. Anat Embryol (Berl). 2003, 206: 185-191.

    CAS  Google Scholar 

  38. 38.

    Vanaerts LA, Blom HJ, Deabreu RA, Trijbels FJ, Eskes TK, Copius Peereboom-Stegeman JH, Noordhoek J: Prevention of neural tube defects by and toxicity of L-homocysteine in cultured postimplantation rat embryos. Teratology. 1994, 50: 348-360.

    CAS  Article  PubMed  Google Scholar 

  39. 39.

    Fell D, Selhub J: Disruption of thymidylate synthesis and glycine-serine interconversion by L-methionine and L-homocystine in Raji cells. Biochim Biophys Acta. 1990, 1033: 80-84. 10.1016/0304-4165(90)90197-5.

    CAS  Article  PubMed  Google Scholar 

  40. 40.

    van der Put NM, Steegers-Theunissen RP, Frosst P, Trijbels FJ, Eskes TK, van den Heuvel LP, Mariman EC, den Heyer M, Rozen R, Blom HJ: Mutated methylenetetrahydrofolate reductase as a risk factor for spina bifida. Lancet. 1995, 346: 1070-1071. 10.1016/S0140-6736(95)91743-8.

    CAS  Article  PubMed  Google Scholar 

  41. 41.

    Whitehead AS, Gallagher P, Mills JL, Kirke PN, Burke H, Molloy AM, Weir DG, Shields DC, Scott JM: A genetic defect in 5,10 methylenetetrahydrofolate reductase in neural tube defects. Qjm. 1995, 88: 763-766.

    CAS  PubMed  Google Scholar 

  42. 42.

    Christensen B, Arbour L, Tran P, Leclerc D, Sabbaghian N, Platt R, Gilfix BM, Rosenblatt DS, Gravel RA, Forbes P, Rozen R: Genetic polymorphisms in methylenetetrahydrofolate reductase and methionine synthase, folate levels in red blood cells, and risk of neural tube defects. Am J Med Genet. 1999, 84: 151-157. 10.1002/(SICI)1096-8628(19990521)84:2<151::AID-AJMG12>3.3.CO;2-K.

    CAS  Article  PubMed  Google Scholar 

  43. 43.

    Shields DC, Kirke PN, Mills JL, Ramsbottom D, Molloy AM, Burke H, Weir DG, Scott JM, Whitehead AS: The "thermolabile" variant of methylenetetrahydrofolate reductase and neural tube defects: An evaluation of genetic risk and the relative importance of the genotypes of the embryo and the mother. Am J Hum Genet. 1999, 64: 1045-1055. 10.1086/302310.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  44. 44.

    Pietrzyk JJ, Bik-Multanowski M: 776C>G polymorphism of the transcobalamin II gene as a risk factor for spina bifida. Mol Genet Metab. 2003, 80: 364-10.1016/S1096-7192(03)00131-8.

    CAS  Article  PubMed  Google Scholar 

  45. 45.

    Martinelli M, Scapoli L, Pezzetti F, Carinci F, Carinci P, Stabellini G, Bisceglia L, Gombos F, Tognon M: C677T variant form at the MTHFR gene and CL/P: a risk factor for mothers?. Am J Med Genet. 2001, 98: 357-360. 10.1002/1096-8628(20010201)98:4<357::AID-AJMG1108>3.0.CO;2-F.

    CAS  Article  PubMed  Google Scholar 

  46. 46.

    O'Leary VB, Parle-McDermott A, Molloy AM, Kirke PN, Johnson Z, Conley M, Scott JM, Mills JL: MTRR and MTHFR polymorphism: link to Down syndrome?. Am J Med Genet. 2002, 107: 151-155. 10.1002/ajmg.10121.

    Article  PubMed  Google Scholar 

  47. 47.

    Shaw GM, Rozen R, Finnell RH, Wasserman CR, Lammer EJ: Maternal vitamin use, genetic variation of infant methylenetetrahydrofolate reductase, and risk for spina bifida. Am J Epidemiol. 1998, 148: 30-37.

    CAS  Article  PubMed  Google Scholar 

  48. 48.

    Molloy AM, Mills JL, Kirke PN, Ramsbottom D, McPartlin JM, Burke H, Conley M, Whitehead AS, Weir DG, Scott JM: Low blood folates in NTD pregnancies are only partly explained by thermolabile 5,10-methylenetetrahydrofolate reductase: low folate status alone may be the critical factor. Am J Med Genet. 1998, 78: 155-159. 10.1002/(SICI)1096-8628(19980630)78:2<155::AID-AJMG11>3.3.CO;2-Z.

    CAS  Article  PubMed  Google Scholar 

  49. 49.

    Morrison K, Papapetrou C, Hol FA, Mariman EC, Lynch SA, Burn J, Edwards YH: Susceptibility to spina bifida; an association study of five candidate genes. Ann Hum Genet. 1998, 62 ( Pt 5): 379-396. 10.1046/j.1469-1809.1998.6250379.x.

    Article  Google Scholar 

  50. 50.

    Boduroglu K, Alikasifoglu M, Anar B, Tuncbilek E: Association of the 677C-->T mutation on the methylenetetrahydrofolate reductase gene in Turkish patients with neural tube defects. J Child Neurol. 1999, 14: 159-161.

    CAS  Article  PubMed  Google Scholar 

  51. 51.

    Johnson WG, Stenroos ES, Heath SC, Chen Y, Carroll R, McKoy VV, Chatkupt S, Lehner T: Distribution of alleles of the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in familial spina bifida. Am J Med Genet. 1999, 87: 407-412. 10.1002/(SICI)1096-8628(19991222)87:5<407::AID-AJMG7>3.3.CO;2-Q.

    CAS  Article  PubMed  Google Scholar 

  52. 52.

    Wenstrom KD, Johanning GL, Owen J, Johnston KE, Acton S, Cliver S, Tamura T: Amniotic fluid homocysteine levels, 5,10-methylenetetrahydrafolate reductase genotypes, and neural tube closure sites. Am J Med Genet. 2000, 90: 6-11. 10.1002/(SICI)1096-8628(20000103)90:1<6::AID-AJMG2>3.0.CO;2-H.

    CAS  Article  PubMed  Google Scholar 

  53. 53.

    Nelen WL, Steegers EA, Eskes TK, Blom HJ: Genetic risk factor for unexplained recurrent early pregnancy loss. Lancet. 1997, 350: 861-10.1016/S0140-6736(97)24038-9.

    CAS  Article  PubMed  Google Scholar 

  54. 54.

    Nelen WL, van der Molen EF, Blom HJ, Heil SG, Steegers EA, Eskes TK: Recurrent early pregnancy loss and genetic-related disturbances in folate and homocysteine metabolism. Br J Hosp Med. 1997, 58: 511-513.

    CAS  PubMed  Google Scholar 

  55. 55.

    Lissak A, Sharon A, Fruchter O, Kassel A, Sanderovitz J, Abramovici H: Polymorphism for mutation of cytosine to thymine at location 677 in the methylenetetrahydrofolate reductase gene is associated with recurrent early fetal loss. Am J Obstet Gynecol. 1999, 181: 126-130.

    CAS  Article  PubMed  Google Scholar 

  56. 56.

    Kumar KS, Govindaiah V, Naushad SE, Devi RR, Jyothy A: Plasma homocysteine levels correlated to interactions between folate status and methylene tetrahydrofolate reductase gene mutation in women with unexplained recurrent pregnancy loss. J Obstet Gynaecol. 2003, 23: 55-58. 10.1080/0144361021000043263.

    CAS  Article  PubMed  Google Scholar 

  57. 57.

    Rey E, Kahn SR, David M, Shrier I: Thrombophilic disorders and fetal loss: a meta-analysis. Lancet. 2003, 361: 901-908. 10.1016/S0140-6736(03)12771-7.

    Article  PubMed  Google Scholar 

  58. 58.

    Foka ZJ, Lambropoulos AF, Saravelos H, Karas GB, Karavida A, Agorastos T, Zournatzi V, Makris PE, Bontis J, Kotsis A: Factor V leiden and prothrombin G20210A mutations, but not methylenetetrahydrofolate reductase C677T, are associated with recurrent miscarriages. Hum Reprod. 2000, 15: 458-462. 10.1093/humrep/15.2.458.

    CAS  Article  PubMed  Google Scholar 

  59. 59.

    Holmes ZR, Regan L, Chilcott I, Cohen H: The C677T MTHFR gene mutation is not predictive of risk for recurrent fetal loss. Br J Haematol. 1999, 105: 98-101. 10.1046/j.1365-2141.1999.01319.x.

    CAS  Article  PubMed  Google Scholar 

  60. 60.

    Kutteh WH, Park VM, Deitcher SR: Hypercoagulable state mutation analysis in white patients with early first-trimester recurrent pregnancy loss. Fertil Steril. 1999, 71: 1048-1053. 10.1016/S0015-0282(99)00133-8.

    CAS  Article  PubMed  Google Scholar 

  61. 61.

    Murphy RP, Donoghue C, Nallen RJ, D'Mello M, Regan C, Whitehead AS, Fitzgerald DJ: Prospective evaluation of the risk conferred by factor V Leiden and thermolabile methylenetetrahydrofolate reductase polymorphisms in pregnancy. Arterioscler Thromb Vasc Biol. 2000, 20: 266-270.

    CAS  Article  PubMed  Google Scholar 

  62. 62.

    Pihusch R, Buchholz T, Lohse P, Rubsamen H, Rogenhofer N, Hasbargen U, Hiller E, Thaler CJ: Thrombophilic gene mutations and recurrent spontaneous abortion: prothrombin mutation increases the risk in the first trimester. Am J Reprod Immunol. 2001, 46: 124-131. 10.1111/j.8755-8920.2001.460202.x.

    CAS  Article  PubMed  Google Scholar 

  63. 63.

    Wramsby ML, Sten-Linder M, Bremme K: Primary habitual abortions are associated with high frequency of factor V Leiden mutation. Fertil Steril. 2000, 74: 987-991. 10.1016/S0015-0282(00)01545-4.

    CAS  Article  PubMed  Google Scholar 

  64. 64.

    Alfirevic Z, Mousa HA, Martlew V, Briscoe L, Perez-Casal M, Toh CH: Postnatal screening for thrombophilia in women with severe pregnancy complications. Obstet Gynecol. 2001, 97: 753-759. 10.1016/S0029-7844(01)01190-5.

    CAS  Article  PubMed  Google Scholar 

  65. 65.

    Gris JC, Quere I, Monpeyroux F, Mercier E, Ripart-Neveu S, Tailland ML, Hoffet M, Berlan J, Daures JP, Mares P: Case-control study of the frequency of thrombophilic disorders in couples with late foetal loss and no thrombotic antecedent--the Nimes Obstetricians and Haematologists Study5 (NOHA5). Thromb Haemost. 1999, 81: 891-899.

    CAS  PubMed  Google Scholar 

  66. 66.

    Kupferminc MJ, Eldor A, Steinman N, Many A, Bar-Am A, Jaffa A, Fait G, Lessing JB: Increased frequency of genetic thrombophilia in women with complications of pregnancy. N Engl J Med. 1999, 340: 9-13. 10.1056/NEJM199901073400102.

    CAS  Article  PubMed  Google Scholar 

  67. 67.

    Many A, Elad R, Yaron Y, Eldor A, Lessing JB, Kupferminc MJ: Third-trimester unexplained intrauterine fetal death is associated with inherited thrombophilia. Obstet Gynecol. 2002, 99: 684-687. 10.1016/S0029-7844(02)01938-5.

    Article  PubMed  Google Scholar 

  68. 68.

    Martinelli I, Taioli E, Cetin I, Marinoni A, Gerosa S, Villa MV, Bozzo M, Mannucci PM: Mutations in coagulation factors in women with unexplained late fetal loss. N Engl J Med. 2000, 343: 1015-1018. 10.1056/NEJM200010053431405.

    CAS  Article  PubMed  Google Scholar 

  69. 69.

    Isotalo PA, Wells GA, Donnelly JG: Neonatal and fetal methylenetetrahydrofolate reductase genetic polymorphisms: an examination of C677T and A1298C mutations. Am J Hum Genet. 2000, 67: 986-990. 10.1086/303082.

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  70. 70.

    Zetterberg H, Regland B, Palmer M, Rymo L, Zafiropoulos A, Arvanitis DA, Spandidos DA, Blennow K: The transcobalamin codon 259 polymorphism influences the risk of human spontaneous abortion. Hum Reprod. 2002, 17: 3033-3036. 10.1093/humrep/17.12.3033.

    CAS  Article  PubMed  Google Scholar 

  71. 71.

    Zetterberg H, Zafiropoulos A, Spandidos DA, Rymo L, Blennow K: Gene-gene interaction between fetal MTHFR 677C>T and transcobalamin 776C>G polymorphisms in human spontaneous abortion. Hum Reprod. 2003, 18: 1948-1950. 10.1093/humrep/deg375.

    CAS  Article  PubMed  Google Scholar 

  72. 72.

    Ramsbottom D, Scott JM, Molloy A, Weir DG, Kirke PN, Mills JL, Gallagher PM, Whitehead AS: Are common mutations of cystathionine beta-synthase involved in the aetiology of neural tube defects?. Clin Genet. 1997, 51: 39-42.

    CAS  Article  PubMed  Google Scholar 

  73. 73.

    Wilson A, Platt R, Wu Q, Leclerc D, Christensen B, Yang H, Gravel RA, Rozen R: A common variant in methionine synthase reductase combined with low cobalamin (vitamin B12) increases risk for spina bifida. Mol Genet Metab. 1999, 67: 317-323. 10.1006/mgme.1999.2879.

    CAS  Article  PubMed  Google Scholar 

  74. 74.

    Kalter H: Folic acid and human malformations: a summary and evaluation. Reprod Toxicol. 2000, 14: 463-476. 10.1016/S0890-6238(00)00093-9.

    CAS  Article  PubMed  Google Scholar 

  75. 75.

    Honein MA, Paulozzi LJ, Mathews TJ, Erickson JD, Wong LY: Impact of folic acid fortification of the US food supply on the occurrence of neural tube defects. Jama. 2001, 285: 2981-2986. 10.1001/jama.285.23.2981.

    CAS  Article  PubMed  Google Scholar 

  76. 76.

    Quinlivan EP, McPartlin J, McNulty H, Ward M, Strain JJ, Weir DG, Scott JM: Importance of both folic acid and vitamin B12 in reduction of risk of vascular disease. Lancet. 2002, 359: 227-228. 10.1016/S0140-6736(02)07439-1.

    CAS  Article  PubMed  Google Scholar 

  77. 77.

    Caballero B: Fortification, supplementation, and nutrient balance. Eur J Clin Nutr. 2003, 57 Suppl 1: S76-8. 10.1038/sj.ejcn.1601803.

    CAS  Article  PubMed  Google Scholar 

  78. 78.

    Kushi LH, Lenart EB, Willett WC: Health implications of Mediterranean diets in light of contemporary knowledge. 1. Plant foods and dairy products. Am J Clin Nutr. 1995, 61: 1407S-1415S.

    CAS  PubMed  Google Scholar 

  79. 79.

    Czeizel AE, Metneki J, Dudas I: Higher rate of multiple births after periconceptional vitamin supplementation. N Engl J Med. 1994, 330: 1687-1688. 10.1056/NEJM199406093302314.

    CAS  Article  PubMed  Google Scholar 

  80. 80.

    Ericson A, Kallen B, Aberg A: Use of multivitamins and folic acid in early pregnancy and multiple births in Sweden. Twin Res. 2001, 4: 63-66. 10.1375/1369052012155.

    CAS  Article  PubMed  Google Scholar 

  81. 81.

    Hasbargen U, Lohse P, Thaler CJ: The number of dichorionic twin pregnancies is reduced by the common MTHFR 677C-->T mutation. Hum Reprod. 2000, 15: 2659-2662. 10.1093/humrep/15.12.2659.

    CAS  Article  PubMed  Google Scholar 

  82. 82.

    Li Z, Gindler J, Wang H, Berry RJ, Li S, Correa A, Zheng JC, Erickson JD, Wang Y: Folic acid supplements during early pregnancy and likelihood of multiple births: a population-based cohort study. Lancet. 2003, 361: 380-384. 10.1016/S0140-6736(03)12390-2.

    CAS  Article  PubMed  Google Scholar 

  83. 83.

    Montgomery GW, Zhao ZZ, Morley KI, Marsh AJ, Boomsma DI, Martin NG, Duffy DL: Dizygotic twinning is not associated with methylenetetrahydrofolate reductase haplotypes. Hum Reprod. 2003, 18: 2460-2464. 10.1093/humrep/deg441.

    CAS  Article  PubMed  Google Scholar 

  84. 84.

    Hook EB, Czeizel AE: Can terathanasia explain the protective effect of folic-acid supplementation on birth defects?. Lancet. 1997, 350: 513-515. 10.1016/S0140-6736(97)01342-1.

    CAS  Article  PubMed  Google Scholar 

  85. 85.

    Windham GC, Shaw GM, Todoroff K, Swan SH: Miscarriage and use of multi-vitamins or folic acid. Am J Med Genet. 2000, 90: 261-262. 10.1002/(SICI)1096-8628(20000131)90:3<261::AID-AJMG18>3.0.CO;2-L.

    CAS  Article  PubMed  Google Scholar 

Download references


This study was supported by the Sahlgrenska University Hospital and the Göteborg Medical Society.

Author information



Corresponding author

Correspondence to Henrik Zetterberg.

Authors’ original submitted files for images

Below are the links to the authors’ original submitted files for images.

Authors’ original file for figure 1

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Zetterberg, H. Methylenetetrahydrofolate reductase and transcobalamin genetic polymorphisms in human spontaneous abortion: biological and clinical implications. Reprod Biol Endocrinol 2, 7 (2004).

Download citation


  • Folate
  • Homocysteine
  • Hyperhomocysteinemia
  • Homocysteine Concentration
  • 677T Allele