Abnormal Folate Metabolism and Mutation in Methylenetetrahydrofolate
Reductase Gene May Be Maternal Risk Factors for Down Syndrome;
James, S. Jill, et al; American Journal For Clinical Nutrition,
volume 70, number 4, October 1999
Scientists recently reported their preliminary study findings and stated that mothers of children with Down syndrome often cannot efficiently metabolize the B vitamin, folic acid.
These researchers had found that almost 60% of the mothers of children with Down syndrome had a mutation which resulted in reduced efficiency of an important enzyme. This genetic abnormality hinders the metabolism of folic acid, and the defective process (known as maternal non-disjunction) is responsible for 95% of all cases of Down syndrome, according to these scientists. About 80% of Down syndrome fetuses spontaneously abort, they reported.
This is especially important for women of pregnancy age since they need that extra folic acid well before they get pregnant. It takes time for the human system to build up a reserve of the vitamin, and a lack of sufficient folic acid at the time the pregnancy begins may result in serious brain and spinal cord birth damage as the fetus develops. There have been hints that folic acid might play a role in other birth defects.
Down Syndrome and Folate Metabolism - 2
Kenneth F. Trofatter, Jr., MD, PhD Director of Maternal-Fetal Medicine and Professor of Clinical Obstetrics
in the Department of Obstetrics and Gynecology of the University of South Carolina
Why is folate metabolism and the methylenetetrahydrofolate reductase (MTHFR)
gene are important?
MTHFR is an enzyme that requires folic acid to convert homocysteine to methionine (an important amino acid) and when this does not occur, homocysteine can accumulate. When this occurs in a developing embryo as the result of either folate deficiency or certain mutations in the
MTHFR gene, this may have a ‘toxic’ effect, increasing the risk for neural tube defects and certain cardiovascular abnormalities. This same biochemical pathway is also essential for the production of a substance called S-adeneosyl methionine that is an essential intermediate in
pathways that add methyl (CH3) groups to nucleic acids (DNA; RNA), proteins, neurotransmitters, and phospholipids, a process that plays an important regulatory role in the biological functions of each of these.
On the basis of evidence that abnormal folate and methyl metabolism can lead to DNA hypomethylation and abnormal chromosomal segregation,” James and colleagues (Am J Clin Nutr 1999;70:429-30) hypothesized in 1999 that young women with the most common MTHFR mutation (C677T) might be at greater risk for having a baby with Down syndrome than their peers who
do not have the mutation. In this study, they evaluated the frequency of the C677T mutation, plasma homocysteine levels, and lymphocyte methotrexate cytotoxicity as indicators of functional folate status in 57 mothers of Down syndrome children and 50 matched controls.
Findings of significantly higher levels of plasma homocysteine and increased sensitivity of lymphocytes to methotrexate cytotocity in the women with Down syndrome babies supported their hypothesis that abnormal folate and methyl metabolism might contribute to the risk
for trisomy 21. Indeed, the women with the C677T MTHFR mutation in this small study had a 2.6-fold higher risk for having a baby with Down syndrome than those who did not.
A subsequent study published by Hobbs and colleagues the next year (Am J Hum Genet 2000;67:623-30) confirmed the preliminary results above. In a cohort of 157 women with Down syndrome babies and 150 matched controls, these investigators not only looked at the prevalence of the C677T MTHFR mutation (technically ‘polymorphism’), but also the
prevalence of a common mutation (A66G) in the methionine synthase reductase (MTRR) gene, another enzyme essential for normal folate metabolism. The presence of the C677T MTHFR mutation was associated with a 1.9-fold greater risk, the presence of the homozygous A66G
MTRR mutation a 2.57-fold risk, and the presence of both polymorphisms a 4.08-fold risk for having a baby with Down syndrome.
Since the publication of the first two studies cited in my last post related to this issue, various groups around the world have investigated the association of abnormalities in folate metabolism and methylation pathways and the risk for Down syndrome. Most studies have demonstrated such an association, although specific findings have differed based on the genetic polymorphisms studied and geographic locations of the study populations. Although these ‘inconsistencies’ might at first lead to doubts about the original findings, they probably can be explained by other differences in genetic backgrounds (geographic variations in types and combinations of polymorphisms) and even geographic differences in dietary habits that might alter the overall deleterious effects of the polymorphisms.
For example, we know that the most common gene mutation in MTHFR (C677T)
(methylenetetrahydrofolate reductase) does not completely inactivate the gene, but reduces its efficiency in catalyzing the biochemical reactions of importance. We also know that this deficiency can be overcome by supplementation with folic acid (hence ‘genetic predisposition’ and ‘environmental factors’) and greatly reduces the rates of neural tube defects. Therefore, women in parts of the world where the ‘usual’ diet is rich in folic acid may not necessarily demonstrate an association between MTHFR C677T and Down syndrome, although other genetic polymorphisms in these metabolic pathways, not readily overcome by folic acid alone, might still show a relationship.
Two studies from Italy illustrate my argument in this regard. In 2003, Stuppia and colleagues (Eur J Hum Genet 2003;11:5) reported that they found no significant difference in MTHFR C677T in 64 mothers of Down syndrome babies compared to 112 matched controls. However, a recent study by Scala, et al., (Genet Med 2006;8:409-16) presented a case-control study of seven polymorphisms of six genes involved in homocysteine/folate pathways and analyzed risks, not only of the single polymorphisms, but of combinations of these as well as well. They demonstrated significant associations between risk for Down syndrome and the presence of either another MTHFR polymorphism (1298C) or of the reduced-folate-carrier1 (RFC1) 80G gene. Furthermore, although carriers of the MTHFR C6777T polymorphism alone were not found to be at greater risk (supporting the earlier study by Stuppia, et al.), women who carried both the MTHFR C677T and 1298C were at significantly greater risk than those carrying either polymorphism alone. (Another recent study by Acacio, et al.
(Prenat Diagn 2005;25:1196-9) from Brazil found women carrying the combination of these same two polymorphisms conferred a 5.7-fold risk for having a baby with Down syndrome).
Chadefaux-Vekemans and colleagues (Pediatr Res 2002;51:766-7) and Bosco, et al. (Am J Med Genet 2203;121:219-24) also found no increased risk associated with MTHFR C677T alone among French women and Sicilian women with Down syndrome babies, but let me remind you, the dietary habits of French, Italian, and Sicilian women, generally, include much higher intakes of folic acid rich foods than that of American women. And, interestingly enough, in the latter study, risk associations were found with both a polymorphism (MTR A2756G) in methionine synthase (3.5-fold risk), yet another enzyme involved in these metabolic pathways, and elevated homocysteine levels (6.7-fold risk). Women who carried both MTR A2756G and MTRR A66G were at 5-fold increased risk.
Other studies from around the world seem to support the association between abnormalities in folic acid/methylation metabolism and the risk for having a baby with Down syndrome, despite population variations. O’Leary and colleagues in Ireland (Am J Med Genet 2002; 107:151-5) evaluated both the MTHFR C677T and the MTRR A66G polymorphisms among women who had Down syndrome babies in their country. They too found no correlation MTHFR C677T alone, but found a significant increase in risk in women who carried either one or two copies of the MTRR A66G polymorphism. Furthermore, women who had both the MTHFR C677T (one or two copies) and two copies of the MTRR A66G polymorphisms were at almost 3-fold risk for having a baby with Down syndrome. The only women who had elevated homocysteine levels were those who carried the MTHFR C677T polymorphism, so the increased risk associated with the MTRR A66G polymorphism did not seem to be reflected in the homocysteine levels of their study population. Rai, et al., (J Hum Genet 2006; 51:278-83) in India found that women who were homozygous (carried two copies) for either the MTHFR C677T or A1298C polymorphisms had risks 7-fold and 4-fold, respectively, and in the case of the former, all the women who had a Down syndrome baby were less than 31 years of age. No such association between age and Down syndrome risk was found for carriers of MTHFR A1298C.
Down syndrome results from the presence of 3 copies of chromosome 21. In 90-95% of cases, the extra chromosome is maternal in origin and results from a failure of normal chromosomal segregation (nondisjunction) during meiosis. This produces one egg (ova) that has 24 chromosomes (22 different chromosomes + 2 copies of chromosome 21) and one egg that has only 22 chromosomes (with no copies of chromosome 21). If the first egg is fertilized by a normal sperm containing 23 different chromosomes, we end up with a baby that has 47 chromosomes rather than 46, and in this case Down syndrome. If the second egg is fertilized, the embryo that is produced has only 45 chromosomes and is nonviable if it has only one copy of chromosome 21 (from the father). Although the risk for trisomy 21 increases with maternal age, most children with Down syndrome are actually born to women less than 30 years of age.
The treatment suggested by this doctor is high doses of folic acid + B vitamins + baby aspirin or anticoagulants*.
MTHFR: 5,10-Methylenetetrahydrofolate Reductase (Þ 5-Methyl-Folate)
Simplified representation of the folate pathway showing the interaction of the various folate methylation states with purine and pyrimidine biosynthesis and the methylation cycle. Genes/proteins are indicated by ovals, whereas the rounded rectangles represent cellular substrates and products of a given gene product. ABCB1, P-glycoprotein; ABCC3, multidrug-resistant protein 3; ATIC, 5-aminoimidazole-4-
carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase; AHCYL1, S-adenosylhomocysteine
hydrolase-like 1; DHFR, dihydrofolate reductase; FPGS, folylpolyglutamyl synthase; GART,
phosphoribosylglycinamide formyltransferase; MAT2A, methionine adenosyltransferase II alpha; MTHFD1, trifunctional methylenetetrahydrofolate dehydrogenase, cyclohydrolase, synthase; MTHFR, methylenetetrahydrofolate reductase; MTR, 5-methyltetrahydrofolate-homocysteine methyltransferase; MTRR, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase; PPAT, phosphoribosyl pyrophosphate amidotransferase; SLC19A1, solute-carrier family 19 (folate transporter), member 1;
5 formyl THF=folinic acid=leucovorin
5 Methyl THF= L-methylfolate=Deplin (medical food)
Folate is one of the 13 essential vitamins. Dihydrofolate, a mixture of polyglutamates (ie, a number of glutamatic acid entities) is the form of folate obtained from dietary intake of green vegetables, yeast, liver, kidney, and egg yolk. Folic acid is the synthetic form of folate contained in over-the-counter vitamin supplements (usually mixed with several other vitamins and nutrients and present in low doses). Folic acid is also the synthetic form of folate contained in prescriptions written by a licensed practitioner in higher doses for medical use.
Dihydrofolate and folic acid are converted to monoglutamate entites by the enzyme alpha-L-glutamyl transferase in the intestinal wall as they are absorbed.47 Once absorbed, monoglutamate entities are converted to MTHF, the form of folate that passes into the brain and is utilized by trimonoamine neurons to facilitate neurotransmitter synthesis (Figures 1 and 4B). Normally, ingesting folate from dihydrofolate in the diet or from folic acid in synthetic supplements will result in adequate delivery of MTHF levels to the brain, especially in those individuals with the more efficient genotype (C677C) producing up to 100% of the enzyme methylene tetrahydrofolate reductase http://www.cnsspectrums.com/aspx/articledetail.aspx?articleid=1267
Lower homocysteine and increase methylation with:
L-methylfolate 1 mg
Methylcobalamin 2 mg
Betaine or trimethylglycine (TMG)
vit B6 as P5P
…the active form of folate called L-5-methyl tetrahydrofolate as Metafolin. Unlike folic acid, this active form of folate requires no additional metabolic steps to be utilized by the body, making it a preferred choice for many individuals. Folate is an essential nutrient for many body processes, including hormone metabolism, DNA synthesis, homocysteine metabolism, and nervous system function.
Metafolin is the end product. Solgar makes a cheaper version.
Genetic polymorphisms involved in folate metabolism and elevated plasma
concentrations of homocysteine: maternal risk factors for Down syndrome in Brazil.
Biselli JM, Goloni-Bertollo EM, Zampieri BL, Haddad R, Eberlin MN, Pavarino-Bertelli EC.
Unidade de Pesquisa em Genética e Biologia Molecular, Faculdade de Medicina de São José do Rio Preto,
São José do Rio Preto, SP, Brasil.
The aim of the present study was to investigate the effect of polymorphisms C677T and A1298C in the methylenetetrahydrofolate reductase (MTHFR) gene, A2756G in methionine synthase reductase (MTR) gene and A80G in reduced folate carrier 1 (RFC1) gene, and plasma homocysteine (Hcy), on the maternal risk for Down syndrome (DS). Seventy-two DS mothers and 194 mothers who had no children with DS were evaluated. The investigation of the MTHFR C677T, MTR A2756G and RFC1 A80G polymorphisms was
performed by polymerase chain reaction and enzyme digestion and the MTHFR A1298C polymorphism by allele-specific polymerase chain reaction. Hcy quantification was carried out by liquid chromatography-tandem mass spectrometry. The median number of polymorphic alleles for the four loci tested was greater in DS mothers compared to the control group, and the presence of three or more polymorphic alleles increased the risk for having a child with DS 1.74 times. Elevated maternal risk for DS was also observed when plasma Hcy concentration was higher than 4.99 micromol/L. In conclusion, the presence of three or more polymorphic alleles for MTHFR C677T, MTHFR A1298C, MTR A2756G, and RFC1 A80G, and plasma Hcy concentrations higher than 4.99 micromol/L are maternal risk factors for DS.
Analysis of seven maternal polymorphisms of genes involved in
homocysteine/folate metabolism and risk of Down syndrome offspring.
Scala I, Granese B, Sellitto M, Salomè S, Sammartino A, Pepe A,
P, Sebastio G, Andria G.
Department of Pediatrics, Federico II University of Naples, via S. Pansini
80131 Naples, Italy.
We present a case-control study of seven polymorphisms of six genes involved in homocysteine/folate pathway as risk factors for Down syndrome. Gene-gene/allele-allele interactions, haplotype analysis and the association with age at conception were also evaluated.
METHODS: We investigated 94 Down syndrome-mothers and 264 control-women from Campania, Italy.
RESULTS: Increased risk of Down syndrome was associated with the methylenetetrahydrofolate reductase (MTHFR) 1298C allele (OR 1.46; 95% CI 1.02-2.10), the MTHFR 1298CC genotype (OR 2.29; 95% CI 1.06-4.96), the reduced-folate-carrier1 (RFC1) 80G allele (1.48;95% CI 1.05-2.10) and the RFC1 80 GG genotype (OR 2.05; 95% CI 1.03-4.07). Significant associations were found between maternal age at conception > or = 34 years and either the MTHFR 1298C or the RFC 180G alleles. Positive interactions were found for the following genotype-pairs: MTHFR 677TT and 1298CC/CA, 1298CC/CA and RFC1 80 GG/GA, RFC1 80 GG and methylenetetrahydrofolate-dehydrogenase 1958 AA. The 677-1298 T-C haplotype at the MTHFR locus was also a risk factor for Down syndrome (P = 0.0022). The methionine-synthase-reductase A66G, the methionine-synthase A2756G and the cystathionine-beta-synthase 844ins68 polymorphisms were not associated with increased risk of Down syndrome.
CONCLUSION: These results point to a role of maternal polymorphisms of homocysteine/folate pathway as risk factors for Down syndrome.
The MTHFR Tutorial – genetic mutation and cause of miscarriage
This is a post on www.FertileThoughts.com forum where Charity kindly put together this information on the MTHFR Gene Issue. This is particularly interesting if you have miscarried, and are not sure of the cause. There more insights in a short article on
MTHFR Gene Mutation
What is it?
The gene MTHFR (Methylenetetrahydofolate Reductase) encodes the protein MTHFR.
Its job is to convert one form of folate (5,10-
another form of folate (5-Methyltetrahydrofolate). 5-Methyltetrahydrofolate is
used to convert Homocysteine (a “bad” amino acid) to Methionine (a “good” amino
acid). Therefore, if MTHFR is not doing its job as well, homocysteine will not
be converted to Methionine and will be elevated in plasma. Elevated
Homocysteine has been associated with a variety of multi-factorial diseases.
Essentially what this means is that the genes that instruct MTHFR to convert
homocysteine to Methionine are mutated and may not be capable of doing this
important function. MTHFR is an enzyme that converts Homocysteine to an
essential amino acid (Methionine). When the genes are mutated you may be
lacking this enzyme. Your Homocysteine levels can possibly climb making the
blood clot. Some doctors don’t check for the MTHFR mutations and rely only on
homocysteine levels. This isn’t as reliable as testing for the mutations,
because Homocysteine levels fluctuate (if you catch your level on a normal day,
you may go undiagnosed).
What Type Do I Have?
With MTHFR, there are two different genes identified for this mutation, and
it’s possible to be “heterozygous,” “compound heterozygous,” or “homozygous.”
The MTHFR gene mutation has varying degrees of possible implications. The order
of potential severity from most to least is:
1. C677T & C677T (Two C Copies – C677T Homozygous)
2. C677T & A1298C (One Copy of Each The C & A – Compound Heterozygous)
3. C677T (One C Copy – C677T Heterozygous)
4. A1298C & A1298C (Two A Copies – A1298C Homozygous)
5. A1298C (One A Copy – A1298C Heterozygous)
The MTHFR mutation is fairly common in the general population. Approximately
44% of the population is heterozygous and another approximate 12% are
homozygous for the MTHFR mutation. Compound heterozygous and homozygous MTHFR
have the highest incidences of being linked to implantation failure, late term
miscarriages, specific birth defects and overall vascular health. Whichever
type of MTHFR you have, it should not be discounted, particularly if there is a
personal or family history of any such incidences.
What Are the Implications?
Any and all of the mutations can affect homocysteine levels, but there is much
dispute as to whether elevated homocysteine levels are actually needed in order
for MTHFR to cause medical complications. Many other MTHFR patients have normal
homocysteine levels; yet have had implantation problems, m/c(s), and/or
stillbirth(s) due to clotting problems. So it is important to find out your
Homocysteine levels (although again, normal doesn’t necessarily mean all is
well). This is a serious field and MTHFR is a serious condition, so consulting
an expert is wise.
Research shows that high homocysteine levels and/or those with the mutation
show a higher propensity for thrombosis (blood clots), arteriosclerosis
(hardening of arteries), Alzheimer’s, stroke, heart attack, Fibromyalgia,
migraines (especially with “Aura” migraines), osteoporotic fractures, bone
marrow disorders and for those of child bearing years, it has found to be
connected to higher incidences of down’s syndrome, spina bifida, other neural
tube defects, trisomy, miscarriage, stillbirth, implantation failure, placental
abruption, preeclampsia, higher incidences of autism, amongst others.
Additionally, if you test positive you may want to have your parents, siblings,
and any children you may already have tested, as well. There are a few
positives to this disorder. Because folate is necessary for cellular division,
there is support that shows having this disorder can actually help keep certain
types of cancer cells from multiplying as rapidly, so there are some benefits
from having this mutation.
Many doctors prescribe Folgard, which is a prescription vitamin supplement
containing high levels of folic acid, B12 and B6. These vitamins are what the
body essentially needs to convert Homocysteine to Methionine. To put this into
perspective, the average multivitamin contains 400 mcgs , most prenatals have
800mcgs of Folic Acid (200% of the normal daily value). Those that are compound
heterozygous and those that are homozygous for the mutation are recommended
taking 5 mgs. of Folic Acid/B vitamins (12 times the average multi-vitamin and
6 times more than prenatals). It is also recommended to begin taking a low dose
(LD) aspirin (81 mgs) once a day, every day, for the rest of your life.
For those undergoing fertility treatments, often times the treatment includes
Lovenox (low molecular weight heparin) or Heparin (both are anti-coagulants)
during the cycle. If you have a history of implantation failure or early
miscarriage, it is becoming more acceptable to use the protocol established by
the well-respected Reproductive Immunologist Dr. Beers by beginning Lovenox
(40mg/once a day) on cycle day 6 and continuing throughout the cycle. If
pregnancy is confirmed, this dosage is likely increased (Typically up to
40mg/twice a day, but potentially higher doses are prescribed dependent upon
blood work results since homocysteine levels tend to increase with pregnancy)
and usage continues throughout your pregnancy. Approximately two to four weeks
prior to birth, the patient is converted to Heparin and continues to take an
anti-coagulant for another 6 weeks postpartum (typically switched back to
During that time, you will typically be directed to take additional Calcium and
Vitamin D, as anti-coagulants can cause bone loss (Heparin more so than
Lovenox). Some doctors will recommend a bone scan after use is discontinued to
ensure there are no bone density issues. While being treated with an anti-coagulant, you will typically be asked to discontinue taking the 81 mg.
baby aspirin since the anti-coagulants will replace the need for the thinning
property of the LD aspirin. The FDA has placed Lovenox in the pregnancy
category B. Lovenox is not expected to be harmful to an unborn baby. It is not
known whether Lovenox passes into breast milk or if it could harm a nursing
baby. Do not use Lovenox without telling your doctor if you are breast-feeding
a baby. However, many doctors believe it is fine to breastfeed for the 6 weeks
postpartum while still receiving Lovenox.
*Should Omega-3 be Part of Your Anticoagulant Therapy?
Omega-3 as an anticoagulant. Does it work?
With heart disease on the rise, many people are turning to omega-3 as part of their anticoagulant therapy. Is this effective? Is it safe? These are some of the questions heart patients are asking and will be discussed in this article.
Omega-3 and anticoagulant therapy
Not yet familiar with omega-3, here's what you need to know. It is an essential fatty acid that plays in important role in brain and cardiovascular health. Omega-3 is a natural blood thinner that helps blood flow easier through the arteries and lowers the risk heart attacks, strokes, and heart disease.
Many types of anticoagulant drugs are available to thin blood, but most of these are very strong and contain serious side effects such as hemorrhagic stroke. Some people take aspirin as a blood thinner. But over time aspirin has the tendency to eat away at intestinal lining causing bleeding and ulcers. For these reasons, many patients turn to omega-3 as a natural blood thinner.
Omega-3 as an anticoagulant - does it work?
As a result of studies performed at the University of Maryland, professionals have come to the following conclusion:
"Strong evidence from population-based clinical studies suggests that omega-3 fatty acid intake (primarily from fish) helps protect against stroke caused by plaque buildup and blood clots in the arteries that lead to the brain. In fact, eating at least 2 servings of fish per week can reduce the risk of stroke by as much as 50%."
This encouraging news is a mere sample of many more studies backing up these findings. However, Robert O. Bonow, MD, of Northwestern University in Chicago is trying to "temper" enthusiasm until further studies are completed.
There is strong evidence that omega-3 consumed in the form of fish oil is very effective in treating heart disease. Heart disease is serious. You should always consult your doctor before attempting to treat yourself with omega-3. If you are interested in trying this method of anticoagulation therapy, consult your doctor before taking omega-3.
Omega-3 full of fat acids are organic blood thinners.
More information about the MTHFR gene:
Cerebral folate deficiency in Down Syndrome
Folic Acid Cut Alzheimer's Risk in Half
Why B12 & Folinic Acid for Down Syndrome
Tests and Treatment for Moms