Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.5.7.1 (methylenetetrahydrofolate reductase)
 2,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Placental infarction or abruption, recurrent pregnancy loss and pre-eclampsia are thought to arise due to defects within the placental vascular bed. Deficiencies of vitamin B12 and folate, or other abnormalities within the methionine-homocyst(e)ine pathway have been implicated in the development of such placental diseases. We conducted a systematic literature review to quantify the risk of placental disease in the presence of these metabolic defects. Studies were identified through OVID Medline between 1966 and February 1999. Terms relating to the measurement of vitamin B12, folic acid, methylenetetrahydrofolate reductase or homocyst(e)ine were combined with those of pre-eclampsia, placental abruption/infarction or spontaneous and habitual abortion. Human studies comprising both cases and controls and published in the English language were accepted. Their references were explored for other publications. Data were abstracted on the matching of cases with controls, the mean levels of folate, B12 or homocyst(e)ine in each group or the frequency of the homozygous state for the thermolabile variant of methylenetetrahydrofolate reductase. The definition of 'abnormal' for each exposure was noted and the presence or absence of the exposure of interest for each outcome was calculated as an absolute rate with a 95 per cent confidence interval. The crude odds ratios were calculated for each study and then pooled using a random effects model. Eighteen studies were finally included. Eight studies examined the risk of placental abruption/infarction in the presence of vitamin B12 or folate deficiency, or hyperhomocyst(e)inaemia. Folate deficiency was a prominent risk factor for placental abruption/infarction among four studies, though not statistically significant (pooled odds ratio 25.9, 95 per cent CI 0.9-736.3). Hyperhomocyst(e)inaemia was also associated with placental abruption/infarction both without (pooled odds ratio 5.3, 95 per cent CI 1.8-15.9) and with methionine loading (pooled odds ratio 4.2, 95 per cent CI 1.2-15.0), as was the homozygous state for methylenetetrahydrofolate reductase (pooled odds ratio 2.3, 95 per cent CI 1.1-4.9). Vitamin B12 deficiency was not a demonstrable risk factor. Eight studies examined blood levels among women with spontaneous abortion or recurrent pregnancy loss. The pooled odds ratios were 3.4 (95 per cent CI 1.2-9.9) for folate deficiency, 3.7 (95 per cent CI 0.96-16.5) for hyperhomocyst(e)inaemia following methionine challenge, and 3.3 (95 per cent CI 1.2-9.2) for the methylenetetrahydrofolate reductase mutation. Five case-control studies examined the relationship between pre-eclampsia and abnormal levels of vitamin B12, folate, homocyst(e)ine or methylenetetrahydrofolate reductase. Folate deficiency was not an associated risk factor (odds ratio 1.2, 95 per cent CI 0.5-2.7), but hyper-homocyst(e)inaemia was (pooled odds ratio 20.9, 95 per cent CI 3.6-121.6). Similarly, homozygosity for the methylenetetrahydrofolate reductase thermolabile variant was associated with a moderate risk of preeclampsia (odds ratio 2.6, 95 per cent CI 1.4-5.1). Some pooled data were associated with significant statistical heterogeneity, however. There is a general agreement among several observational studies that folate deficiency, hyperhomocyst(e)inaemia and homozygosity for the methylenetetrahydrofolate reductase thermolabile variant are probable risk factors for placenta-mediated diseases, such as pre-eclampsia, spontaneous abortion and placental abruption. Vitamin B12 deficiency is less well defined as an important risk factor. Due to the limited quality of these data, including insufficient matching of cases with controls, and possible laboratory measurement bias relating to pregnancy, prospective studies are needed to confirm these findings and guide future preventative and therapeutic research.
Placenta 1999 Sep
PMID:Folic acid and homocyst(e)ine metabolic defects and the risk of placental abruption, pre-eclampsia and spontaneous pregnancy loss: A systematic review. 1045 5

It is well understood that maternal folate deficiency can cause abnormal fetal development. However, the extent to which placental development and function are also dependent upon folate uptake and metabolism remains unclear. To understand which trophoblast cell types may be affected by folate deficiency or abnormal folate metabolism, we completed a comprehensive spatial and temporal protein expression analysis of folate receptor (Folr), folate transporters (proton-coupled folate receptor [Slc46a1 or PCFT] and reduced folate carrier-1 [Rfc1]) and folate metabolic enzymes (5,10-methylenetetrahydrofolate reductase [Mthfr] and methionine synthase [Mtr]) in histological sections of mouse placentas from early development (E8.5) until term (E18.5). We observed that the highest level of protein expression was during early development (E8.5-E10.5), prior to the formation of the three main layers of the mature placenta suggesting that folate uptake and metabolism may be required for placental development, itself. As expected, the labyrinth trophoblast cells, which are responsible for nutrient transport, expressed these proteins throughout pregnancy, including robust expression in the sinusoidal trophoblast giant cells that line the maternal blood spaces. Other trophoblast giant cell (TGC) subtypes (parietal-TGCs and canal-TGCs), whose function does not include nutrient transport, expressed folate transporters and enzymes from E8.5 onwards. Remarkably, these proteins were also detected in glycogen trophoblast cells from E12.5-E18.5 suggesting a new role in folate uptake and metabolism for these cells. Together, these data provide evidence that folate may be necessary for normal placental development and function, and perturbations in its availability or metabolism may lead to secondary effects on fetal development.
Placenta 2012 May
PMID:Spatial and temporal expression of folate-related transporters and metabolic enzymes during mouse placental development. 2236 88