Greetings, I apologize in advance for the length of this post. In addition to wanting others' feedback/opinions/advice, I thought the info about this (atypical?) case might be helpful to someone else some day, just as I have found other posts here to be helpful. My wife has been diagnosed with POTS, with no neuropathy and onset in her fourth decade (i.e., she does not have the NET gene polymorphism). She has gone from basically normal to significantly disabled over the course of the last two years or so. She has most of the typical POTS symptoms, and a few others that I gather are not necessarily typical: A. marked irritability, with conditions of mild stress sometimes provoking episodes of rage, especially during the premenstrual period B. somewhat elevated iron status, despite not being a homozygote either of the two predominant hemochromatosis polymorphisms C. elevated IGF-1, with MRI being negative for pituitary adenoma D. adrenal fatigue E. mildly disturbed gonadotropin levels, estrogen dominance, polycystic ovaries (as revealed by laparoscopy) Given the results of Esler et al. [1], I believe that her case is likely due to epigenetic silencing of the NET gene. This inspired me to learn all I could about DNA methylation and the methionine cycle, with [2] being particularly informative. We were also compelled to measure her plasma homocysteine, which came out as 3.4 umol/L. I gather that plasma homocysteine should be about 7.5 umol/L, plus or minus 1 or 2 umol/L. The distribution is positively skewed, so readings 4 umol/L below 7.5 are less likely than reading 4 umol/L above 7.5. Apparently these measurements vary across labs, but from what I have read she may be below the 1st percentile of the distribution. Conditions of unusually low homocysteine seem to be barely on the radar of the medical profession. Exceptions are an extremely rare congenital condition that results in death in the first year of life (I forget the name), and autistic children, as described in [3]. The average plasma homocysteine for the children in that study was 5.8 umol/L, with the lowest among them being 4.0 umol/L. I am wondering if, like those autistic children, my wife has a decreased ability to cope with oxidative stress and impaired methylation capacity. More specifically, I wonder if there is a vicious cycle at work: orthostatic tachycardia --> chronically high aerobic energy production --> chronically high oxidative stress --> chronically high need for glutathione production and/or impaired adenosine to ATP conversion --> low homocysteine --> low SAM levels, impaired methylation capacity --> epigenetic silencing of the NET gene (altered expression of other genes as well?) --> orthostatic tachycardia --> ... A mysterious aspect of this is the cause of the low homocysteine. Is it low because so much of it is being transulfurated for cysteine (and eventually glutathione) production? Or is it low because high levels of adenosine, the other product of the SAH to homocysteine reaction, are suppressing homocysteine production? For the autistic children, [3] offers the latter explanation. But who knows for POTS? Our actions so far since discovering this about her homocysteine: I) bedrest -- this is to minimize tachycardia, aerobic energy production, and oxidative stress II) folinic acid, sub-lingual methyl-B12, and trimethylglyceine supplementation -- these are to encourage transmethylation of homocysteine and increase methionine levels III) n-acetyl-cysteine supplementation -- to increase glutathione levels and reduce the need for transsulfuration of homocysteine IV) weaning off of methyl predinsolone. Corticosteriods modulate the transulfuration of homocysteine [2]. With the exception of an initial boost, it wasn't really helping anyway. V) glutamine supplementation -- enhances gut production of glutathione VI) creatine supplementation -- this is intended to free up more SAM for methylation reactions other than creatine production. From [2]: "Creatine synthesis significantly influences the SAM/SAH ratio as it represents the bulk of SAM consumption... If a pathalogical condition is being worsened owing to competition of DNMTs with numerous other methyl transfer pathways as well as the inhibitory effects of SAH, lightening the burden of creatine synthesis may well have ameliorating effects." Also, this should help support intracellular energy levels and functioning if the adenosine to ATP pathway is impaired by oxidative stress [4]. After a month and a half on this program, her mood and energy levels have improved somewhat, although the potential for rage episodes persists especially during the premenstrual week. Heart rate increments are as bad as ever (she can sometimes run up to 150+ bpm after 15 or 20 minutes of standing). We have only just finally gotten completely off of the methyl prednisolone (which was very difficult). Hopefully more improvement is forthcoming. Questions for others here: Q1) Has anyone here been identified as having unusually low homocysteine? If so, what remedial action was taken? Q2) Any idea what type of specialist would recognize unusually low homocysteine as a problem? Better still, does anyone know of a doctor that would listen to me and seriously consider all of this (rather than just resigning us to symptom management)? We would happily travel. Thanks for reading, and thanks for any input or suggestions! References: [1] http://www.ncbi.nlm.nih.gov/sites/entrez?D...Search=16785272 [2] http://www.ncbi.nlm.nih.gov/sites/entrez?D...Search=15809266 [3] http://www.ncbi.nlm.nih.gov/sites/entrez?D...Search=15585776 [4] http://www.healingpediatrics.com/articles/...20oxidation.ppt