Plasma Methylmalonic Acid Research Articles

Is folate deficiency a common cause of distal symmetric polyneuropathy in Zambian clinics?

ObjectivesTo evaluate the odds of vitamin B12 and folate deficiencies among Zambian clinic attendees with distal symmetric polyneuropathy (DSP) and age, sex, and HIV matched controls. MethodsCases were adults from clinics in urban/peri-urban Zambia. Controls were enrolled among persons not seeking personal medical care, such as a caregiver or person collecting antiretrovirals without a medical complaint. Participants underwent structured interviews, physician examination, and assessments of complete blood count, renal and liver profiles, serum vitamin B12 and folate, erythrocyte folate, plasma total homocysteine and methylmalonic acid. HIV testing and CD4 counts were performed when appropriate. ResultsAmong 107 consenting matched case-control pairs, 65% were female, 52% HIV positive, with mean age of 47.6 (SD 13.5) years. Among HIV positive participants, mean CD4 count was 484 (SD 221) and 482 (SD 236) for cases and controls, respectively (p = .93). DSP symptoms and severity did not differ by HIV status (p's > 0.05). Height, history of tuberculosis treatment, alcohol use, education, asset index, dietary diversity, and nutritional supplement use did not differ between cases and controls (p's > 0.05). DSP cases had at least 3:1 odds of having low serum folate (p = .0001), severely low erythrocyte folate (p = .014), and elevated total homocysteine (p = .001) levels compared to controls. Markers of vitamin B12 deficiency were not associated with case status (p's > 0.05). ConclusionMarkers of folate deficiency are highly associated with DSP among Zambian clinic attendees. Future studies should consider a broader range of comorbid nutritional deficiencies, and strategies for interventions.

P1531The association between plasma choline and acute myocardial infarction is modified by potential markers of endogenous PPAR activation

Abstract Background Choline is related to lipid handling and higher plasma concentrations have been associated with an adverse cardiovascular risk profile. However, previous studies have suggested that the relationship between plasma free choline and later cardiovascular events may differ according to patient phenotypes. Purpose To explore the risk association between plasma choline and later acute myocardial infarction (AMI) according to plasma methylmalonic acid (MMA) or dimethylglycine (DMG). The latter two metabolites are suggested markers of endogenous activation of perixosome proliferator-activated receptors (PPARs), which are nuclear receptor proteins involved in lipid metabolism. Methods Risk relationships were explored by Cox regression among 2232 patients evaluated for suspected stable angina pectoris in the overall population and according to median plasma MMA and DMG. Results Baseline plasma choline was related to several cardiovascular risk factors (Table 1). After median follow-up of 7.3 years, 338 patients were reported with at least one incident AMI. In the overall population, the age and gender adjusted HR (95% CI) for each increment of 1 SD log-transformed plasma choline and AMI was 1.21 (1.08–1.35), P=0.001, and the association persisted in multivariate analyses. In patients with plasma MMA or DMG≥median, the HRs (95% CIs) were 1.33 (1.16–1.54) and 1.38 (1.20–1.58), respectively, both P<0.0001; however no significant relationships were observed between plasma choline and later AMI among patients with either plasma MMA or DMG < median (P interaction <0.008) (Figure 1). <MEDIAN (P> Table 1. Baseline characteristics according to plasma choline quartiles Quartile 1 Quartile 4 P for trend Age, years 58 (52–66) 66 (58–73) <0.0001 Smoking, n (%) 212 (37.9) 153 (27.9) <0.0001 Diabetes, n (%) 61 (10.9) 85 (15.5) 0.12 Previous acute myocardial infarction, n (%) 200 (35.7) 238 (43.4) <0.0001 Estimated glomerular filtration rate, mL/min/1.73m2 96 (87–104) 79 (63–92) <0.0001 Serum hs-troponin T, ng/L 4 (3–8) 9 (4–17) 0.0002 Serum triglycerides, mmol/L 1.35 (1.00–2.03) 1.60 (1.16–2.25) <0.0001 Serum apolipoprotein A1, mg/L 1.29 (1.12–1.51) 1.32 (1.17–1.53) 0.01 Statin therapy, n (%) 384 (68.6) 435 (79.4) 0.01 Figure 1 Conclusion Among patients with stable angina, plasma choline was related to increased long-term AMI risk among patients with higher plasma MMA or DMG only. This finding potentially reflects increased risk conferred by choline during concomitant endogenous PPAR activation. Acknowledgement/Funding None

Added dietary cobalt or vitamin B12, or injecting vitamin B12 does not improve performance or indicators of ketosis in pre- and post-partum Holstein-Friesian dairy cows

Vitamin B12 is synthesised in the rumen from cobalt (Co) and has a major role in metabolism in the peri-paturient period, although few studies have evaluated the effect of the dietary inclusion of Co, vitamin B12 or injecting vitamin B12 on the metabolism, health and performance of high yielding dairy cows. A total of 56 Holstein-Friesian dairy cows received one of four treatments from 8 weeks before calving to 8 weeks post-calving: C, no added Co; DC, additional 0.2 mg Co/kg dry matter (DM); DB, additional 0.68 mg vitamin B12/kg DM; IB, intra-muscular injection of vitamin B12 to supply 0.71 mg/cow per day prepartum and 1.42 mg/cow per day post-partum. The basal and lactation rations both contained 0.21 mg Co/kg DM. Cows were weighed and condition scored at drying off, 4 weeks before calving, within 24 h of calving and at 2, 4 and 8 weeks post-calving, with blood samples collected at drying off, 2 weeks pre-calving, calving and 2, 4 and 8 weeks post-calving. Liver biopsy samples were collected from all animals at drying off and 4 weeks post-calving. Live weight changed with time, but there was no effect of treatment (P>0.05), whereas cows receiving IB had the lowest mean body condition score and DB the highest (P<0.05). There was no effect of treatment on post-partum DM intake, milk yield or milk fat concentration (P>0.05) with mean values of 21.6 kg/day, 39.6 kg/day and 40.4 g/kg, respectively. Cows receiving IB had a higher plasma vitamin B12 concentration than those receiving any of the other treatments (P<0.001), but there was no effect (P>0.05) of treatment on homocysteine or succinate concentrations, although mean plasma methylmalonic acid concentrations were lower (P=0.019) for cows receiving IB than for Control cows. Plasma β-hydroxybutyrate concentrations increased sharply at calving followed by a decline, but there was no effect of treatment. Similarly, there was no effect (P>0.05) of treatment on plasma non-esterified fatty acids or glucose. Whole tract digestibility of DM and fibre measured at week 7 of lactation were similar between treatments, and there was little effect of treatment on the milk fatty acid profile except for C15:0, which was lower in cows receiving DC than IB (P<0.05). It is concluded that a basal dietary concentration of 0.21 mg Co/kg DM is sufficient to meet the requirements of high yielding dairy cows during the transition period, and there is little benefit from additional Co or vitamin B12.

Mice lacking the transcobalamin-vitamin B12 receptor, CD320, suffer from anemia and reproductive deficits when fed vitamin B12-deficient diet.

In humans, poor nutrition, malabsorption and variation in cobalamin (vitamin B12) metabolic genes are associated with hematological, neurological and developmental pathologies. Cobalamin is transported from blood into tissues via the transcobalamin (TC) receptor encoded by the CD320 gene. We created mice carrying a targeted deletion of the mouse ortholog, Cd320. Knockout (KO) mice lacking this TC receptor have elevated levels of plasma methylmalonic acid and homocysteine but are otherwise healthy, viable, fertile and not anemic. To challenge the Cd320 KO mice we maintained them on a vitamin B12-deficient diet. After 5 weeks on this diet, reproductive failure develops in Cd320 KO females but not males. In vitro, homozygous Cd320 KO embryos from cobalamin-deficient Cd320 KO dams develop normally to embryonic day (E) 3.5, while in vivo, few uterine decidual implantation sites are observed at E7.5, suggesting that embryos perish around the time of implantation. Dietary restriction of vitamin B12 induces a severe macrocytic anemia in Cd320 KO mice after 10-12 months while control mice on this diet are anemia-free up to 2 years. Despite the severe anemia, cobalamin-deficient KO mice do not exhibit obvious neurological symptoms. Our results with Cd320 KO mice suggest that an alternative mechanism exists for mice to transport cobalamin independent of the Cd320 encoded receptor. Our findings with deficient diet are consistent with historical and epidemiological data suggesting that low vitamin B12 levels in humans are associated with infertility and developmental abnormalities. Our Cd320 KO mouse model is an ideal model system for studying vitamin B12 deficiency.

Factors correlating to the propensity of general practitioners to substitute borderline vitamin B12 deficiency

Objective: This study aims to identify factors which correlate to the propensity of general practitioners (GPs) to prescribe supplementation for borderline vitamin B12 deficiency.Design: Cross-sectional surveys were distributed in person.Setting: Conferences held in Cairns, Palm Cove Beach, Mt Isa; educational meetings in Atherton; and meetings with individual general practices within the Cairns and Hinterland region. All located in Queensland, Australia.Subjects: 128 practicing GP specialists and registrars (practitioners in training).Main outcome measures: Responses to the Likert scale statements with its five options scaling from ‘strongly disagree’ to ‘strongly agree’ were recoded to have binary outcomes for analysis.Results: A survey response rate of 89% was achieved. Participants who felt patient demands influence the management of borderline vitamin B12 deficiency were more likely to prescribe supplementation (OR 2.4, p = 0.037). Participants who perceived an overuse of vitamin B12 were less likely to prescribe B12 (OR 0.39, p = 0.019). Participants who often saw patients with vitamin B12 deficiency were less likely to request for the complementary biomarkers plasma methylmalonic acid or total homocysteine (OR 0.41, p = 0.045).Conclusions: The identified disparity to prescribe vitamin B12 for borderline deficiency may be described as an attempt in the GP collective to seek a balance between being the patient’s or the society’s doctor. We propose that relevant authorities try to reduce this disparity by describing a management strategy for borderline vitamin B12 deficiency.Key pointsGeneral practitioners hold different thresholds for commencing supplementation in cases of borderline vitamin B12 deficiency.Participants from Australia were asked to fill out a cross-sectional survey to explore factors which correlate with the propensity to prescribe in clinical practice.Our study identified that patient demands and a practitioner’s perception of whether there is an overuse of vitamin B12 in the community influenced the propensity to treat for deficiency.The results give insight into reasons for initiating supplementation, and will help inform general practitioners on their current management.

Improved testing for vitamin B12 deficiency: correcting MMA for eGFR reduces the number of patients classified as vitamin B12 deficient.

Background Methylmalonic acid (MMA) can detect functional vitamin B12 deficiencies as it accumulates early when intracellular deficits arise. However, impaired clearance of MMA from blood due to decreased glomerular filtration rate (eGFR) also results in elevated plasma MMA concentrations. Alternative to clinical trials, a data mining approach was chosen to quantify and compensate for the effect of decreased eGFR on MMA concentration. Methods Comprehensive data on patient's vitamin B12, eGFR and MMA concentrations were collected ( n = 2906). The relationship between vitamin B12, renal function (eGFR) and MMA was modelled using weighted multiple linear regression. The obtained model was used to estimate the influence of decreased eGFR on MMA. Clinical impact was examined by comparing the number of patients labelled vitamin B12 deficient with and without adjustment in MMA. Results Adjusting measured MMA concentrations for eGFR in the group of patients with low-normal vitamin B12 concentrations (90-300 pmol/L) showed that the use of unadjusted MMA concentrations overestimates vitamin B12 deficiency by 40%. Conclusions Through a data mining approach, the influence of eGFR on the relation between MMA and vitamin B12 can be quantified and used to correct the measured MMA concentration for decreased eGFR. Especially in the elderly, eGFR-based correction of MMA may prevent over-diagnosis of vitamin B12 deficiency and corresponding treatment.

Cobalamin and Folate Status among Breastfed Infants in Bhaktapur, Nepal.

Cobalamin and folate are crucial micronutrients during infancy and they are required for growth and cognitive development. Due to the monotonous and predominantly vegetarian-based complementary feeding and poor maternal micronutrient status, infants from low- and middle-income countries are susceptible to cobalamin deficiency. However, data on plasma cobalamin and folate and the functional markers methylmalonic acid and total homocysteine from breastfed infants in Nepal are still needed. We collected plasma samples from 316 6–11-month-old breastfed infants with a length-for-age of less than minus one z-score and analyzed blood for plasma folate, cobalamin, methylmalonic acid and total homocysteine concentrations. Cobalamin deficiency (plasma cobalamin <148 pmol/L) was found among 11%, whereas 24% of the infants had plasma cobalamin concentrations between 148–221 pmol/L. Elevated total homocysteine (>10 µmol/L) and methylmalonic acid (>0.28 µmol/L) indicating functional cobalamin deficiency were found among 53% and 75% of the infants, respectively. Based on a combined indicator of cobalamin status, 58% were found to have low cobalamin status. However, folate deficiency (<10 nmol/L) was not found as the lowest value of plasma folate was 20.7 nmol/L. It is important to examine the extent to which poor cobalamin status during infancy has immediate or long-term consequences.

Maternal Serum Cobalamin at 18 Weeks of Pregnancy Predicts Infant Cobalamin Status at 6 Months—A Prospective, Observational Study

An adequate maternal cobalamin status is crucial for fetal and infant neurodevelopment. Pregnancy-induced physiologic changes make evaluation of maternal cobalamin status in pregnancy difficult. We have investigated maternal cobalamin status during pregnancy in order to establish a maternal cobalamin concentration which secures an optimal infant cobalamin status during the first 6 mo of life. In an observational, prospective study, markers of cobalamin status including serum cobalamin, plasma total homocysteine (tHcy), and plasma methylmalonic acid (MMA) were assessed in healthy pregnant women (n=114) from week 18 of pregnancy through 6 mo postpartum and related to infant cobalamin status at 6 mo. Healthy, never-pregnant women aged 18-40 y (n=123) were included as controls. Compared to controls, all markers of cobalamin status were lower in pregnant women. Median serum cobalamin concentration progressively decreased from week 18 to week 36 of pregnancy (356 to 302 pmol/L, P<0.001) and increased by >40% by 6 wk postpartum (518 pmol/L). The metabolic markers increased from week 18 of pregnancy to 6 wk postpartum: median plasma tHcy 3.9 to 7.7 μmol/L (P<0.001), and MMA 0.13 to 0.17 μmol/L (P<0.001). The serum cobalamin concentration of infants at age 6 mo correlated with maternal serum cobalamin concentration during pregnancy and postpartum (rho=0.36-0.55, P<0.001). A maternal serum cobalamin concentration <394 pmol/L during week 18 of pregnancy was associated with an increased risk (OR: 4.2; 95% CI: 1.5, 11.5) of infant biochemical cobalamin deficiency at 6 mo (defined as tHcy ≥6.5 μmol/L). The maternal serum cobalamin concentration in early pregnancy is a strong predictor for later maternal and infant cobalamin status. To secure an optimal infant cobalamin status during the first 6 mo of life, we recommend a maternal serum cobalamin concentration >394 pmol/L at week 18 of pregnancy. This should be confirmed in an intervention study. This trial was registered at clinicaltrials.gov as NCT03272022.

Early pregnancy folate-cobalamin interactions and their effects on cobalamin status and hematologic variables throughout pregnancy

Periconception folic acid supplementation is widespread, but how it interacts with cobalamin status is rarely considered. The aim of this study was to investigate whether first-trimester folate-cobalamin interactions affect pregnancy cobalamin status, hematologic variables, and pregnancy outcomes. In the longitudinal Reus-Tarragona Birth Cohort study from <12 gestational weeks throughout pregnancy, fasting plasma and red blood cell (RBC) folate, plasma cobalamin, holotranscobalamin (holoTC), methylmalonic acid (MMA), total homocysteine (tHcy), hemoglobin, mean cell volume (MCV), postglucose-load serum glucose, gestational hypertension, gestational age at birth, and birth weight were recorded in 563 participants. The highest plasma folate concentrations occurred in the first trimester when folic acid supplement use was extensive. Supplementation beyond the first trimester interacted with time of pregnancy on plasma folate, RBC folate, and tHcy throughout pregnancy (P-interaction<0.001). Plasma folate and RBC folate were higher and tHcy was lower in continued supplement users than in nonusers. Elevated plasma folate (≥30 nmol/L) occurred in 78.9% of women who exceeded the recommended 400µg folic acid/d. First-trimester folate-cobalamin status interactions were associated with MMA (P-interaction<0.001) throughout pregnancy. When plasma cobalamin was suboptimal (≤221 pmol/L; n=36), participants with elevated plasma folate (n=11) had higher MMA concentrations than did those with nonelevated plasma folate (n=23). First-trimester folate-MMA status interactions were associated with MCV throughout pregnancy (P-interaction<0.01) and with cord plasma holoTC (P-interaction<0.05). The mean difference (95% CI) in MCV (fL) between women with elevated and nonelevated plasma folate status was -2.12 (-3.71, -0.52) for top-quartile plasma MMA (≥0.139 µmol/L) and 0.60 (-0.39, 1.60) for plasma MMA<0.139 µmol/L. Cord plasma holoTC was higher in women with elevated compared with nonelevated plasma folate status only for MMA<0.139 µmol/L. Folate-cobalamin interactions were not associated with the other investigated outcomes. First-trimester folate-cobalamin status interactions were associated with plasma MMA and MCV throughout pregnancy. This trial was registered at www.clinicaltrials.gov as NCT01778205.

Systemic Messenger RNA Therapy as a Treatment for Methylmalonic Acidemia

Isolated methylmalonic acidemia/aciduria (MMA) is a devastating metabolic disorder with poor outcomes despite current medical treatments. Like other mitochondrial enzymopathies, enzyme replacement therapy (ERT) is not available, and although promising, AAV gene therapy can be limited by pre-existing immunity and has been associated with genotoxicity in mice. To develop a new class of therapy for MMA, we generated a pseudoU-modified codon-optimized mRNA encoding human methylmalonyl-CoA mutase (hMUT), the enzyme most frequently mutated in MMA, and encapsulated it into biodegradable lipid nanoparticles (LNPs). Intravenous (i.v.) administration of hMUT mRNA in two different mouse models of MMA resulted in a 75%-85% reduction in plasma methylmalonic acid and was associated with increased hMUT protein expression and activity in liver. Repeat dosing of hMUT mRNA reduced circulating metabolites and dramatically improved survival and weight gain. Additionally, repeat i.v. dosing did not increase markers of liver toxicity or inflammation in heterozygote MMA mice.

The Human Serum Metabolome of Vitamin B-12 Deficiency and Repletion, and Associations with Neurological Function in Elderly Adults

The specific metabolomic perturbations that occur in vitamin B-12 deficiency, and their associations with neurological function, are not well characterized. We sought to characterize the human serum metabolome in subclinical vitamin B-12 deficiency and repletion. A before-and-after treatment study provided 1 injection of 10 mg vitamin B-12 (with 100 mg pyridoxine and 100 mg thiamin) to 27 community-dwelling elderly Chileans (∼74 y old) with vitamin B-12 deficiency, as evaluated with serum vitamin B-12, total plasma homocysteine (tHcy), methylmalonic acid (MMA), and holotranscobalamin. The combined indicator of vitamin B-12 status (cB-12) was computed. Targeted metabolites [166 acylcarnitines, amino acids, sugars, glycerophospholipids, and sphingolipids (liquid chromatography-tandem mass spectrometry)], and untargeted metabolites [247 chemical entities (gas chromatography time-of-flight mass spectrometry)] were measured at baseline and 4 mo after treatment. A peripheral nerve score was developed. Differences before and after treatment were examined. For targeted metabolomics, the data from 18 individuals with adequate vitamin B-12 status (selected from the same population) were added to the before-and-after treatment data set. Network visualizations and metabolic pathways are illustrated. The injection increased serum vitamin B-12, holotranscobalamin, and cB-12 (P < 0.001), and reduced tHcy and serum MMA (P < 0.001). Metabolomic changes from before to after treatment included increases (P < 0.001) in acylcarnitines, plasmalogens, and other phospholipids, whereas proline and other intermediaries of one-carbon metabolism-that is, methionine and cysteine-were reduced (P < 0.001). Direct significant correlations (P < 0.05 after the false discovery rate procedure) were identified between acylcarnitines, plasmalogens, phospholipids, lyso-phospholipids, and sphingomyelins compared with vitamin B-12 status and nerve function. Multiple connections were identified with primary metabolites (e.g., an inverse relation between vitamin B-12 markers and tryptophan, tyrosine, and pyruvic, succinic, and citric acids, and a direct correlation between the nerve score and arginine). The human serum metabolome in vitamin B-12 deficiency and the changes that occur after supplementation are characterized. Metabolomics revealed connections between vitamin B-12 status and serum metabolic markers of mitochondrial function, myelin integrity, oxidative stress, and peripheral nerve function, including some previously implicated in Alzheimer and Parkinson diseases. This trial was registered at www.controlled-trials.com as ISRCTN02694183.

A Black Cohosh Extract Causes Hematologic and Biochemical Changes Consistent with a Functional Cobalamin Deficiency in Female B6C3F1/N Mice.

Black cohosh rhizome, available as a dietary supplement, is most commonly marketed as a remedy for dysmenorrhea and menopausal symptoms. A previous subchronic toxicity study of black cohosh dried ethanolic extract (BCE) in female mice revealed a dose-dependent ineffective erythropoiesis with a macrocytosis consistent with the condition known as megaloblastic anemia. The purpose of this study was to investigate potential mechanisms by which BCE induces these particular hematological changes. B6C3F1/N female mice (32/group) were exposed by gavage to vehicle or 1,000 mg/kg BCE for 92 days. Blood samples were analyzed for hematology, renal and hepatic clinical chemistry, serum folate and cobalamin, red blood cell (RBC) folate, and plasma homocysteine and methylmalonic acid (MMA). Folate levels were measured in liver and kidney. Hematological changes included decreased RBC count; increased mean corpuscular volume; and decreased reticulocyte, white blood cell, neutrophil, and lymphocyte counts. Blood smear evaluation revealed increased Howell-Jolly bodies and occasional basophilic stippling in treated animals. Plasma homocysteine and MMA concentrations were increased in treated animals. Under the conditions of our study, BCE administration caused hematological and clinical chemistry changes consistent with a functional cobalamin, and possibly folate, deficiency. Further studies are needed to elucidate the mechanism by which BCE causes increases in homocysteine and MMA.

Ratios of One-Carbon Metabolites Are Functional Markers of B-Vitamin Status in a Norwegian Coronary Angiography Screening Cohort

Background: Functional (metabolic) markers of B-vitamin status, including plasma total homocysteine (tHcy) for folate and plasma methylmalonic acid (MMA) for vitamin B-12, suffer from moderate sensitivity and poor specificity. Ratios of metabolites belonging to the same pathway may have better performance characteristics.Objective: We evaluated the ratios of tHcy to total cysteine (tCys; Hcy:Cys), tHcy to creatinine (Hcy:Cre), and tHcy to tCys to creatinine (Hcy:Cys:Cre) as functional markers of B-vitamin status represented by a summary score composed of folate, cobalamin, betaine, pyridoxal 5'-phosphate (PLP), and riboflavin concentrations measured in plasma.Methods: Cross-sectional data were obtained from a cohort of patients with stable angina pectoris (2994 men and 1167 women) aged 21-88 y. The relative contribution of the B-vitamin score, age, sex, smoking, body mass index, and markers of renal function and inflammation to the variance of the functional B-vitamin markers was calculated by using multiple linear regression.Results: Compared with tHcy alone, Hcy:Cys, Hcy:Cre, and Hcy:Cys:Cre all showed improved sensitivity and specificity for detecting plasma B-vitamin status. Improvements in overall performance ranged from 4-fold for Hcy:Cys to ∼8-fold for Hcy:Cys:Cre and were particularly strong in subjects with the common 5,10-methylenetetrahydrofolate reductase (MTHFR) 677CC genotype.Conclusions: Ratios of tHcy to tCys and/or creatinine showed a severalfold improvement over tHcy alone as functional markers of B-vitamin status in Norwegian coronary angiography screenees. The biological rationale for these ratios is discussed in terms of known properties of enzymes involved in the catabolism of homocysteine and synthesis of creatine and creatinine.

Vitamin B-12 status in infancy is positively associated with development and cognitive functioning 5 y later in Nepalese children

Background: Poor vitamin B-12 (cobalamin) status is widespread in South Asia. Insufficient vitamin B-12 status has been linked to poor neurodevelopment in young children.Objective: We measured the associations between vitamin B-12 status in infancy (2–12 mo) and the development and cognitive functioning in Nepalese children 5 y later.Design: Vitamin B-12 status was assessed in infancy with the use of plasma cobalamin, total homocysteine (tHcy), and methylmalonic acid (MMA). At 5 y of age, we measured development with the use of the Ages and Stages Questionnaire, 3rd edition (ASQ-3), and cognitive functioning by using the Developmental Neuropsychological Assessment, 2nd edition (NEPSY II), in 320 children. In regression models, we estimated the associations between vitamin B-12 status, including a combined indicator of vitamin B-12 status (3cB12) and scores on the ASQ-3 and NEPSY II subtests.Results: All markers of vitamin B-12 status with the exception of plasma cobalamin were significantly associated with the total ASQ-3 scores in the multiple regression models. A 1-unit increase in the 3cB12 score was associated with an increase in the total ASQ-3 score of 4.88 (95% CI: 2.09, 7.68; P = 0.001). Increases in both plasma tHcy and MMA (indicating poorer status) were associated with a decrease in scores on the NEPSY II affect recognition and geometric puzzle subtests. Each unit increment in 3cB12 scores was associated with increases of 0.82 (95% CI: 0.49, 1.14; P < 0.0005), 0.59 (95% CI: 0.10, 1.09; P = 0.020), and 0.24 (95% CI: 0.02, 0.47; P = 0.035) in the affect recognition, geometric puzzle, and block construction scores, respectively.Conclusions: Vitamin B-12 status in infancy is associated with development and performance on social perception tasks and visuospatial abilities at 5 y of age. The long-term effects of poor vitamin B-12 status in infancy need further investigation in randomized controlled trials.

South Asian Ethnicity Is Related to the Highest Risk of Vitamin B12 Deficiency in Pregnant Canadian Women.

Vitamin B12 (B12) adequacy during pregnancy is crucial for maternal health and optimal fetal development; however, suboptimal B12 status has been reported in pregnant Canadian women. Methylmalonic acid (MMA) is a sensitive indicator of B12 status. Since few studies have measured MMA during pregnancy in Canadian women, the objective of this study was to evaluate B12 status in pregnant women living in Metro Vancouver, using both plasma total B12 and MMA. We recruited a convenience sample of 320 pregnant women between 20 and 35 gestational weeks from local healthcare facilities. Plasma total B12 concentrations indicative of deficiency (<148 pmol/L) and suboptimal B12 status (148–220 pmol/L) were found in 18% and 33% of the women, respectively. Normal plasma MMA concentration (<210 nmol/L) was observed in 82% of all women. Gestational age was a strong predictor of plasma total B12 and MMA concentration, and South Asian ethnicity of B-12 deficiency and MMA concentrations. Overall, there was a high discrepancy between the prevalence of B12 inadequacy depending on the biomarker used. Independently, however, South Asian women were at particular risk for B12 deficiency, likely due to lower animal source food intake. Further study of this vulnerable group and performance testing of B12 biomarkers is warranted.

Folate and Vitamin B12-Related Biomarkers in Relation to Brain Volumes.

Aim: We investigated cross-sectional associations between circulating homocysteine, folate, biomarkers of vitamin B12 status and brain volumes. We furthermore compared brain volumes of participants who received daily folic acid and vitamin B12 supplementation with participants who did not. Methods: Participants of the B-PROOF study (n = 2919) were assigned to 400 µg folic acid and 500 µg vitamin B12, or a placebo. After two years of intervention, T1-weighted magnetic resonance imaging (MRI) scans were made in a random subsample (n = 218) to obtain grey and white matter volume, and total brain volume (TBV). Plasma homocysteine, serum folate, vitamin B12, holotranscobalamin, and methylmalonic acid concentrations were measured. Results: Multiple linear regression analyses showed inverse associations between plasma homocysteine with TBV (β = −0.91, 95% CI −1.85–0.03; p = 0.06) and between serum folate and TBV (β = −0.20, 95% CI −0.38, −0.02; p = 0.03). No significant associations were observed for serum vitamin B12 and holotranscobalamin. Fully adjusted ANCOVA models showed that the group that received B-vitamins had a lower TBV (adjusted mean 1064, 95% CI 1058–1069 mL) than the non-supplemented group (1072, 95% CI 1067–1078 mL, p = 0.03). Conclusions: Results were contradictory, with higher Hcy levels associated with lower TBV, but also with higher folate levels associated with lower TBV. In addition, the lack of a baseline measurement withholds us from giving recommendations on whether folic acid and vitamin B12 supplementation will be beneficial above and beyond normal dietary intake for brain health.

Perioperative management of living-donor liver transplantation for methylmalonic acidemia.

Methymalonic acidemia (MMA) is a hereditary metabolic disorder characterized by a defect of the methylmalonyl-CoA mutase that breaks down propionate. The efficacy of liver transplantation for MMA was recently reported. However, the anesthetic management of liver transplant for MMA is not clear. The aim of this article is to describe an anesthetic management algorithm of liver transplant for MMA by reviewing our cases of liver transplant for MMA. Fourteen patients received a liver transplant; three cases showed metabolic decompensation during the transplant and two of the patients died. In the two patients who expired, propofol was used for maintenance anesthesia and preoperative continuous hemodiafiltration was used to reduce plasma methylmalonic acid level in one case, and to control severe metabolic decompensation before transplant for the other case. Their renal function was also worse than others and they were already experiencing metabolic decompensation before induction of anesthesia. Based on our experience of these 14 cases, we have established an anesthetic algorithm for patients with MMA undergoing liver transplant or other procedures. There are three important points in our experience: propofol should be avoided, dextrose infusion therapy should be continued to prevent metabolic decompensation, and liver transplant or other procedures should be avoided during metabolic decompensation.

Homocysteine metabolism and the associations of global DNA methylation with selected gene polymorphisms and nutritional factors in patients with dementia

Epigenetics (particularly DNA methylation) together with environmental and genetic factors, are key to understanding the pathogenesis of many diseases including dementia. Disturbances in DNA methylation have already been implicated in dementia. Homocysteine metabolism, with folate and vitamin B12 as essential cofactors, is integral to methylation processes.We evaluated in a case-control study the association of global DNA methylation, homocysteine, folate and vitamin B12 status with dementia. Selected polymorphisms of genes previously associated with dementia development and the influence of various factors on DNA methylation were also investigated.102 patients with dementia (53 with Alzheimer's disease, 17 with vascular dementia and 32 with mixed dementia) were recruited. The non-demented controls consisted of 45 age-matched subjects without dementia and 47 individuals with mild cognitive impairment. Global DNA methylation was determined by Imprint Methylated DNA Quantification Kit MDQ1 (Sigma-Aldrich, Gillingham, Dorset, UK). Plasma homocysteine, serum folate and vitamin B12 were determined by chemiluminescence. Plasma and erythrocyte 5-methyltetrahydrofolate and plasma methylmalonic acid (markers of folate and vitamin B12 status) were measured by HPLC. APOE, PON1 p.Q192R, MTHFR 677C>T (c.665C>T) and IL1B-511C>T polymorphisms were identified using PCR-RFLP methods.Patients with dementia had significantly higher concentrations of homocysteine (p=0.012) and methylmalonic acid (p=0.016) and lower folate (p=0.002) and plasma 5-methyltetrahydrofolate (p=0.005) than non-demented subjects. There was no difference in DNA methylation between patients and controls. A non-significant tendency to higher DNA methylation in patients with vascular dementia (p=0.061) was observed. Multivariate regression analysis of all recruited individuals demonstrated a significant positive association between DNA methylation and folate (p=0.013), creatinine (p=0.003) concentrations and IL1B-511T (p=0.002) and PON1 192R (p=0.049) alleles and negative association with fasting glucose (p=0.004).The biochemical results showed significantly lower folate and vitamin B12 status in demented patients than controls. Global DNA methylation was associated with markers of folate status, creatinine, glucose and PON1 and IL1B polymorphisms.

Low Serum Vitamin B-12 Concentrations Are Prevalent in a Cohort of Pregnant Canadian Women

Background: Among Canadian women of reproductive age, 5% and 20% have serum vitamin B-12 concentrations indicative of deficiency (<148 pmol/L) and marginal status (148–220 pmol/L), respectively. Given the association between suboptimal vitamin B-12 and adverse pregnancy outcomes, an understanding of vitamin B-12 status during pregnancy, and factors that influence it, is required.Objective: This prospective analysis from the PREFORM (PREnatal FOlic acid exposuRe on DNA Methylation in the newborn infant) study investigated 1) vitamin B-12 status in a cohort of Canadian pregnant women and their newborns, 2) the association of maternal dietary vitamin B-12 intake with maternal and cord blood concentrations of vitamin B-12 and its biomarkers, and 3) the association of fetal genetic polymorphisms with cord blood concentrations of vitamin B-12 and its biomarkers.Methods: In pregnant Canadian women (n = 368; mean ± SD age: 32 ± 5 y), vitamin B-12 intakes were assessed in early (0–16 wk) and mid- to late (23–37 wk) pregnancy. Serum vitamin B-12 and plasma total homocysteine (tHcy) and methylmalonic acid (MMA) in maternal blood at 12–16 wk of pregnancy and at delivery (28–42 wk) and in cord blood were measured and compared by using regression analyses. The associations of 28 fetal genetic variants in vitamin B-12 metabolism and cord blood vitamin B-12, tHcy, and MMA concentrations were assessed by using regression analysis, with adjustment for multiple testing.Results: A total of 17% and 38% of women had deficient and 35% and 43% had marginal serum vitamin B-12 concentrations at 12–16 wk of pregnancy and at delivery, respectively. Only 1.9–5.3% had elevated MMA (>271 nmol/L), and no women had elevated tHcy (>13 μmol/L). Maternal dietary vitamin B-12 intake during pregnancy was either weakly associated or not associated with maternal and cord blood vitamin B-12 (r2 = 0.17–0.24, P < 0.0008), tHcy (P = NS) and MMA (r2 = 0.05–0.11, P < 0.001). Fetal genetic polymorphisms were not associated with cord blood concentrations of vitamin B-12 and its biomarkers.Conclusions: Deficient and marginal serum vitamin B-12 concentrations are prevalent in Canadian pregnant women with the use of traditional cutoffs, despite supplement use. Given the growing interest among women to adhere to a vegetarian diet that may be lower in vitamin B-12, and vitamin B-12’s importance in pregnancy, the functional ramifications of these observations need to be elucidated. This trial was registered at clinicaltrials.gov as NCT02244684.

353. 1-13C-Propionate Oxidation as a Measure of Methylmalonyl-CoA Mutase (MUT) Activity in Methylmalonic Acidemia

Isolated methylmalonic acidemia (MMA) is a grave autosomal recessive inborn error of metabolism, caused by a defect in methylmalonyl-CoA mutase (MUT). In some severe patients, liver (LT), kidney (KT), or combined liver and kidney (LKT) transplantation has been used as a surgical treatment for MMA. Previous studies have shown that 1-13C-propionate oxidation can be used to measure whole body MUT activity in gene therapy treated and transgenic MMA mice and have encouraged translation to patients, with the aim of using this approach as an outcome measure in future gene therapy clinical trials.We therefore investigated 1-13C-propionate oxidation in 29 patients with isolated MMA (mut0 N=17, mut− N=6, cblA N=5, cblB N=1, age range: 4-41 years), including 3 KT, 1 LT, and 4 LKT recipients, as well as one patient who received a heterotopic liver allograft post KT (hLKT). In addition, 7 healthy volunteers (3 males, 4 females, age range: 21-44 years) and 8 heterozygote controls (age range:35-62 years) were tested to establish test reproducibility. Baseline CO2 production of the participants was measured using an indirect calorimetry cart before sodium 1-13C-propionate was administered as an oral or G-tube bolus, and breath samples were collected serially over 2 hours via disposable breath collection kits to measure 13CO2 enrichment and subsequently propionate oxidation.Propionate oxidation was decreased in all non-transplanted MMA patients compared with controls (p<0.0001). Both LT and LKT recipients demonstrated complete restoration of oxidation rates to control levels (p=NS), while only minimal oxidation was observed in the single hLKT recipient. KT recipients responsive to vitamin B-12 supplementation (N=2) with cblA MMA showed oxidation rates similar to controls. However, the remaining KT recipient, a severely affected mut0 patient carrying two stop mutations, showed almost no metabolism of label.Repeat testing conducted both on healthy volunteers in triplicate and 7 MMA patients (6 mut, 1 cblA) in duplicate supported excellent reproducibility. Notably, similar oxidation rates were observed in 2 patients despite markedly different plasma methylmalonic acid concentrations between one assessment and the next (1741 vs. 2246 and 2260 vs. 719 µmol/L). This suggests that measured 1-13C-propionate oxidation may be a more consistent and reproducible clinical biomarker than plasma metabolites that depend, in part, on protein intake and kidney function.Our results demonstrate that 1-13C-propionate oxidation, measured using breath testing, has great potential as an outcome measure for therapeutic interventions aimed at increasing hepatic MUT activity, such as gene or cell therapy. It is safe, non-radioactive, minimally invasive, well tolerated by very young patients, and can be frequently repeated over the course of treatment to evaluate the magnitude and sustainability of whole body in vivo MUT activity, with every patient's baseline values serving as an individual pre-treatment control. Furthermore, the method is readily applicable to the study of other inborn errors of metabolism affecting propionate oxidation, such as propionic acidemia.