J'ai trouvé ce résumé très intéréssant, sur comment interpréter un "methylation panel" (réalisable ici: http://www.europeanlaboratory.nl/). Bon ça date de 2011 deja, mais dans le fond je trouve ça bien résumé et clair pour ceux qui ont fait (ou feront) cette analyse. Malheureusement, entre temps Rich Van est décédé, donc pas la peine de demander une mise a jour ou de lui envoyer un email sur l'adresse indiqué
Je pense que couplé a l'analyse de 23andme (pour le profil génétique de methylation et les SNP associés), et permet d'etre sur de la ou ça coince (ce qui n'est pas forcément le cas en se basant uniquement sur les SNP de la génétique, car les un peuvent contrebalancer les autres et ainsi dessuite...)
Pti gars
-----------------------------------------------------------
Interpretation of the Methylation Pathways Panel (2011)
Richard A. Van Konynenburg, Ph.D.
Independent Researcher
(richvank@aol.com)
Disclaimer: The Methylation Pathways Panel is offered by the European Laboratory of Nutrients in the Netherlands and the Health Diagnostics and Research Institute in New Jersey, USA. I am not affiliated with these laboratories, but have been a user of this panel, and have written these suggestions at the request of Tapan Audhya, Ph.D., Director of Research for the Health Diagnostics lab, for the benefit of physicians who may not be familiar with this panel.
My suggestions for the interpretation of results of the panel are based on my study of the biochemistry involved, on my own experience with interpreting panel results as part of the analysis of a fairly large number of cases of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) over the past four years, and on discussion of some of the issues with Dr. Audhya.
I am a researcher, not a licensed physician. Treatment decisions based on the results of applying this panel and its interpretation to individual cases are the responsibility of the treating physician.
Application: In addition to being useful in analyzing cases of ME/CFS, this panel can also be usefully applied to cases of autism and other disorders that involve abnormalities in glutathione, methylation and the folate metabolism.
The panel includes measurement of two forms of glutathione (reduced and oxidized), S-adenosylmethionine (SAMe), S-adenosylhomocysteine (SAH), adenosine, and seven folate derivatives.
According to Dr. Audhya (personal communication), the reference ranges shown on the lab reports for each of these metabolites were derived from measurements on at least 120 healthy male and female volunteer medical students from ages 20 to 40, non-smoking, and with no known chronic diseases. The reference ranges extend to plus and minus two standard deviations from the mean of these measurements.
Glutathione (reduced): This is a measurement of the concentration of the chemically reduced (active) form of glutathione (abbreviated GSH) in the blood plasma. The reference range is 3.8 to 5.5 micromoles per liter.
Glutathione reductase:
Glutathione plays many important roles in the biochemistry of the body, including serving as the basis of the antioxidant enzyme system, participating in the detoxication system, and supporting the cell-mediated immune response, all of which exhibit deficits in CFS. The level of GSH in the plasma is likely to be more reflective of tissue intracellular glutathione status than the more commonly and more easily measured red blood cell or (essentially equivalent) whole blood glutathione level, which is about three orders of magnitude greater, because red blood cells are normally net producers of glutathione. Also, knowledge of the level of the reduced form, as distinguished from total (reduced plus oxidized) glutathione, which is more commonly measured, is more diagnostic of the status of glutathione function.
In order to be able to approximate the in vivo level of reduced glutathione when blood samples must be shipped to a lab, it is necessary to include special enzyme inhibitors in the sample vials, and these are included in the test kit supplied by these two laboratories.
Most people with chronic fatigue syndrome (PWCs), but not all, are found to have values of GSH that are below the reference range*. This means that they are suffering from glutathione depletion. As they undergo treatment to lift the partial methylation cycle block, this value usually rises into the normal range over a period of a few months. I believe that this is very important, because
glutathione normally participates in the intracellular metabolism of vitamin B12, and if it is low, a functional deficiency of vitamin B12 results, and insufficient methylcobalamin is produced to support methionine synthase in the methylation cycle.
In my view, this is the mechanism that causes the onset of ME/CFS. This functional deficiency is not detected in a conventional serum B12 test, but will produce elevated methylmalonate in a urine organic acids test. In my opinion, many of the abnormalities and symptoms in ME/CFS can be traced directly to glutathione depletion.
Anecdotal evidence suggests that PWCs who do not have glutathione depletion do have abnormalities in the function of one or more of the enzymes that make use of glutathione, i.e. the glutathione peroxidases and/or glutathione transferases. This may be due to genetic polymorphisms or DNA adducts on the genes that code for these enzymes, or in the case of some of the glutathione peroxidases, to a low selenium status.
Glutathione (oxidized): This is a measurement of the concentration of the oxidized form of glutathione (abbreviated GSSG) in the blood plasma. The reference range is 0.16 to 0.50 micromoles per liter.
Normally, oxidized glutathione in the cells is recycled back to reduced glutathione by glutathione reductase, an enzyme that requires vitamin B2 and NADPH. If this reaction is overwhelmed by oxidative stress, the cells export excess GSSG to the plasma. In some (but not all) PWCs, GSSG is elevated above the normal range, and this represents oxidative stress. It is more common in CFS to see this level in the high-normal range. This value may increase slightly under initial treatment of a partial methylation cycle block.*
Ratio of Glutatione (reduced) to Glutathione (oxidized): This is not shown explicitly on the panel results, but can be calculated from them. It is a measure of the redox potential in the plasma, and reflects the state of the antioxidant system in the cells. The normal mean value is 14. PWCs often have a value slightly more than half this amount, indicating a state of glutathione depletion and oxidative stress. This ratio has been found to increase during treatment of a partial methylation cycle block.*
S-adenosymethionine (RBC): This is a measure of the concentration of S-adenosylmethionine (SAMe) in the red blood cells. The reference range is 221 to 256 micromoles per deciliter.
SAMe is produced in the methylation cycle and is the main supplier of methyl (CH3) groups for a large number of methylation reactions in the body, including the methylation of DNA and the biosynthesis of creatine, carnitine, coenzyme Q10, melatonin and epinephrine. This measurement is made in the red blood cells because the level there reflects an average over a longer time and is less vulnerable to fluctuations than is the plasma level of SAMe.
Most PWCs have values below the reference range, and treatment raises the value.* A low value for SAMe represents a low methylation capacity, and in CFS, it usually appears to result from an inhibition or partial block of the enzyme methionine synthase in the methylation cycle. Many of the abnormalities in CFS can be tied to lack of sufficient methylation capacity.
S-adenosylhomocysteine (RBC): This is a measure of the concentration of S-adenosylhomocysteine (SAH) in the red blood cells. The reference range is 38.0 to 49.0 micromoles per deciliter.
SAH is the product of the many methyltransferase reactions that utilize SAMe as a source of methyl groups. In CFS, its value ranges from below the reference range to above the reference range. Values appear to be converging toward the reference range with treatment.
Sum of SAM and SAH: When the sum of SAM and SAH is below about 268 micromoles per deciliter, it appears to suggest the presence of upregulating polymorphisms in the cystathionine beta synthase (CBS) enzyme, though this may not be true in every case. For those considering following the Yasko treatment program, this may be useful information.
Ratio of SAM to SAH: A ratio less than about 4.5 represents low methylation capacity. Both the concentration of SAM and the ratio of concentrations of SAM to SAH are important in determining themethylation capacity, because they affect the rates of the methyltransferase reactions.
Adenosine: This is a measure of the concentration of adenosine in the blood plasma. The reference range is 16.8 to 21.4 x 10(-8) molar.
Adenosine is a product of the reaction that converts SAH to homocysteine. It is also exported to the plasma when mitochondria develop a low energy charge, so that ATP drops down to ADP, AMP, and eventually, adenosine. Adenosine in the plasma is normally broken down to inosine by the enzyme adenosine deaminase.
In some PWCs adenosine is found to be high, in some it is low, and in some it is in the reference range. I don’t yet understand what controls the adenosine level in these patients, and I suspect that there is more than one factor involved. In most PWCs who started with abnormal values, the adenosine level appears to be moving into the reference range with methylation cycle treatment, but more data are needed.
5-CH3-THF: This is a measure of the concentration of 5L-methyl tetrahydrofolate in the blood plasma. The reference range is 8.4 to 72.6 nanomoles per liter.
This form of folate is present in natural foods, and is normally the most abundant form of folate in the blood plasma. It is the form that serves as a reactant for the enzyme methionine synthase, and is thus the important form for the methylation cycle. It is also the only form of folate that normally can enter the brain. Its only known reactions are the methionine synthase reaction and reaction with the oxidant peroxynitrite.
When there is a partial block in methionine synthase, 5L-CH3-THF drains from the cells into the blood plasma by the so-called “methyl trap” mechanism. As other forms of folate are converted to 5L-CH3-THF, this mechanism depletes the cells of folates in general.
Many PWCs have a low value of 5L-CH3-THF, consistent with a partial block in the methylation cycle. Most methylation treatment protocols include supplementation with 5L-CH3-THF, which is sold over-the-counter as Metafolin, FolaPro, or MethylMate B (trademarks), and in the prescription “medical foods” supplied by PamLab, including Deplin, CerefolinNAC and Metanx. There are some others on the market that include both racemic forms (5L and 5R) of this folate.
When methylation treatment is used, the level of 5-CH3-THF rises in nearly every PWC. If the concentration of 5-CH3-THF is within the reference range, but either SAM or the ratio of SAM to SAH is below the reference values, it suggests that there is a partial methylation cycle block and that it is caused by inavailability of sufficient bioactive B12, rather than inavailability of sufficient folate. A urine organic acids panel will show elevated methylmalonate if there is a functional deficiency of B12. I have seen this combination frequently, and I think it demonstrates that the functional deficiency of B12 is the immediate root cause of most cases of partial methylation cycle block. Usually glutathione is low in these cases, which is consistent with such a functional deficiency. As the activity of the methylation cycle becomes more normal, the demand for 5-CH3-THF will likely increase, so including it in the treatment protocol, even if not initially low, will likely be beneficial.
10-Formyl-THF: This is a measure of the concentration of 10-formyl tetrahydrofolate in the blood plasma. The reference range is 1.5 to 8.2 nanomoles per liter.
This form of folate is involved in reactions to form purines, which form part of RNA and DNA as well as ATP. It is usually on the low side in PWCs, likely as a result of the methyl trap mechanism mentioned above. This deficiency is likely the reason for some elevation of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) often seen in PWCs. This deficit may also impact replacement of cells lining the gut, as well as white blood cells.
5-Formyl-THF: This is a measure of the concentration of 5-formyl tetrahydrofolate (also called folinic acid) in the blood plasma. The reference range is 1.2 to 11.7 nanomoles per liter.
This form is not used directly as a substrate in one-carbon transfer reactions, but it can be converted into other forms of folate, and may serve as a buffer form of folate. Most but not all PWCs have a value on the low side. It is one of the supplements in some methylation protocols. It can be converted to 5L-CH3-THF in the body by a series of three reactions, one of which requires NADPH, and it may also help to supply other forms of folate until the methionine synthase reaction comes up to more normal activity.
THF: This is a measure of the concentration of tetrahydrofolate in the blood plasma. The reference range is 0.6 to 6.8 nanomoles per liter.
This is the fundamental chemically reduced form of folate from which several other reduced folate forms are synthesized, and thus serves as the “hub” of the folate metabolism. THF is also a product of the methionine synthase reaction, and participates in the reaction that converts formiminoglutamate (figlu) into glutamate in the metabolism of histidine. If figlu is found to be elevated in a urine organic acids panel, it usually indicates that THF is low. In PWCs it is lower than the mean normal value of 3.7 nanomoles per liter in most but not all PWCs.
Folic acid: This is a measure of the concentration of folic acid in the blood plasma. The reference range is 8.9 to 24.6 nanomoles per liter.
Folic acid is a synthetic form of folate, not found in nature. It is added to food grains in the U.S. and some other countries in order to lower the incidence of neural tube birth defects, including spina bifida. It is the oxidized form of folate, and therefore has a long shelf life and is the most common commercial folate supplement. It is normally converted into THF by two sequential reactions catalyzed by dihydrofolate reductase (DHFR), using NADPH as the reductant. However, some people are not able to carry out this reaction well for genetic reasons, and PWCs may be depleted in NADPH, so folic acid is not the best supplemental form of folate for these people.
Low values suggest folic acid deficiency in the current diet. High values, especially in the presence of low values for THF, may be associated with inability to convert folic acid into reduced folate readily, such as because of a genetic polymorphism in the DHFR enzyme. They may also be due to high supplementation of folic acid.
Folinic acid (WB): This is a measure of the concentration of folinic acid in the whole blood. The reference range is 9.0 to 35.5 nanomoles per liter.
See comments on 5-formyl-THF above. Whole blood folinic acid usually tracks with the plasma 5-formyl-THF concentration.
Folic acid (RBC): This is a measure of the concentration of folic acid in the red blood cells. The reference range is 400 to 1500 nanomoles per liter.
The red blood cells import folic acid when they are initially being formed, but during most of their lifetime, they do not normally import, export, or use it. They simply serve as reservoirs for it, giving it up when they are broken down.
Many PWCs have low values of this parameter. This can be caused by a low folic acid status in the diet over the previous few months, since the population of RBCs at any time has ages ranging from zero to about four months. However, in CFS it can also be caused by oxidative damage to the cell membranes, which allows folic acid to leak out of the cells. Dr. Audhya reports that treatment with omega-3 fatty acids has been found to raise this value over time in one cohort.
If anyone finds errors in the above suggestions, I would appreciate being notified at richvank@aol.com.
* Nathan, N., and Van Konynenburg, R.A., Treatment Study of Methylation Cycle Support in Patients with Chronic Fatigue Syndrome and Fibromyalgia, poster paper, 9th International IACFS/ME Conference, Reno, Nevada, March 12-15, 2009. (http://www.mecfs-vic.org.au/sites/ww…ethylStudy.pdf)
