The association between serum methylmalonic acid, cobalamin-related biomarkers, and long-term mortality risk in cancer survivors: a prospective cohort study.

BACKGROUND: Elevated serum methylmalonic acid (MMA), a marker of cobalamin (vitamin B12) deficiency, has been linked to cancer progression. However, the impact of MMA or cobalamin on mortality risk in cancer survivors remains unknown. OBJECTIVES: To explore the relationship between MMA, serum, dietary, and supplement of cobalamin, MMA metabolism-related genes, and poor prognosis in adult cancer survivors. METHODS: We analyzed data from 1988 cancer survivors aged ≥20 y. Patients were selected from the National Health and Nutrition Examination Survey and followed up until December 31, 2019. Weighted Cox proportional hazard regression was used to estimate hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) for mortality risk assessment. Genomic analysis identified MMA metabolism-related genes linked to early death in a 33-cancer-type cohort from The Cancer Genome Atlas. RESULTS: Among 1988 participants, 872 deaths occurred over a 10-year follow-up. Higher serum MMA levels were significantly linked to increased long-term mortality risk (tertile 3 compared with tertile 1: adjusted HR: 1.37; 95% CI: 1.11, 1.70; P-trend < 0.001). No associations were found between serum, dietary, and supplement of cobalamin and cancer survivor mortality (each P-trend > 0.143). However, MMA-associated mortality was notable in patients without deficiency. When combining cobalamin and MMA categories, multivariate-adjusted HR (95% CI) for all-cause mortality was 2.06 (95% CI: 1.60, 2.65) in participants with >250 nmol/L and cobalamin >295.1 pmol/L compared with those with MMA ≤250 nmol/L and cobalamin >295.1 pmol/L. Moreover, reduced transcriptional levels of MMA metabolism-related genes, indicating decreased mitochondrial MMA metabolism capability, are linked to an unfavorable prognosis in certain cancer types. CONCLUSIONS: Serum MMA was associated with long-term mortality risk in adult cancer survivors, which was more significant among individuals with higher levels of serum cobalamin. These findings suggest that mortality related to MMA was attributed to the insufficient flux of MMA metabolism, not cobalamin deficiency.

Associations of serum vitamin B12 and its biomarkers with musculoskeletal health in middle-aged and older adults.

Introduction: The effects of vitamin B12 metabolism on musculoskeletal health and the exact mechanism have not been fully determined. Our study aimed to assess the association of vitamin B12 and its biomarkers with musculoskeletal health in middle-aged and older adults. Methods: The data from the National Health and Nutrition Examination Survey 2001-2002 were used to investigate the effects of serum vitamin B12 and its biomarkers (homocysteine and methylmalonic acid) on skeletal muscle health. Bone mineral density (BMD), lean mass, gait speed and knee extensor strength were used as indicators for musculoskeletal health. Results: Serum vitamin B12 level was positively correlated with the total and appendicular lean mass (ß = 584.83, P = 0.044; ß = 291.65, P = 0.043) in older adults over 65 years of age. In the full population, plasma homocysteine was associated with total lean mass, appendicular lean mass, gait speed, and knee extensor strength (all P < 0.05). Among older adults over 65 years of age, homocysteine level was significantly negatively correlated with gait speed and knee extensor strength (ß = -12.75, P = 0.019; ß = -0.06, P <0.001). Plasma methylmalonic acid was negatively associated with total BMD and femur BMD in the full population (ß = -0.01, P = 0.018; ß = -0.01, P = 0.004). In older adults, methylmalonic acid significantly affected total BMD, femur BMD and knee extensor strength (ß = -0.01, P = 0.048; ß = -0.01, P = 0.025; ß = -7.53, P = 0.015). Conclusions: Vitamin B12 and its biomarkers are closely related to BMD, body composition, muscle strength and physical function in middle-aged and older adults. Vitamin B12 may be an important indicator of musculoskeletal health in the elderly.

[Clinical features and follow-up study on 55 patients with adolescence-onset methylmalonic acidemia].

Objective: To investigate the clinical features and outcomes of adolescence-onset methylmalonic acidemia (MMA) and explore preventive strategies. Methods: This was a retrospective case analysis of the phenotypes, genotypes and prognoses of adolescence-onset MMA patients. There were 55 patients diagnosed in Peking University First Hospital from January 2002 to June 2023, the data of symptoms, signs, laboratory results, gene variations, and outcomes was collected. The follow-ups were done through WeChat, telephone, or clinic visits every 3 to 6 months. Results: Among the 55 patients, 31 were males and 24 were females. The age of onset was 12 years old (range 10-18 years old). They visited clinics at Tanner stages 2 to 5 with typical secondary sexual characteristics. Nine cases (16%) were trigged by infection and 5 cases (9%) were triggered by insidious exercises. The period from onset to diagnosis was between 2 months and 6 years. Forty-five cases (82%) had neuropsychiatric symptoms as the main symptoms, followed by cardiovascular symptoms in 12 cases (22%), kidney damage in 7 cases (13%), and eye disease in 12 cases (22%). Fifty-four cases (98%) had the biochemical characteristics of methylmalonic acidemia combined with homocysteinemia, and 1 case (2%) had the isolated methylmalonic acidemia. Genetic diagnosis was obtained in 54 cases, with 20 variants identified in MMACHC gene and 2 in MMUT gene. In 53 children with MMACHC gene mutation,1 case had dual gene variants of PRDX1 and MMACHC, with 105 alleles. The top 5 frequent variants in MMACHC were c.482G>A in 39 alleles (37%), c.609G>A in 17 alleles (16%), c.658_660delAAG in 11 alleles (10%), c.80A>G in 10 alleles (10%), c.567dupT and c.394C>T both are 4 alleles (4%). All patients recovered using cobalamin, L-carnitine, betaine, and symptomatic therapy, and 54 patients (98%) returned to school or work. Conclusions: Patients with adolescence-onset MMA may triggered by fatigue or infection. The diagnosis is often delayed due to non-specific symptoms. Metabolic and genetic tests are crucial for a definite diagnosis. Treatment with cobalamin, L-carnitine, and betaine can effectively reverse the prognosis of MMA in adolescence-onset patients.

Vitamin B12 status and hyperhomocysteinemia in patients with Rheumatoid arthritis treated with methotrexate and folic acid.

BACKGROUND: Rheumatoid arthritis (RA) is an inflammatory arthritis in which the immune system targets synovial joints. Methotrexate serves as the mainstay of treatment for RA due to its efficacy. However, patients treated with methotrexate are uniquely at risk for vitamin B12 deficiency and hyperhomocysteinemia due to coincident disease risk factors and the fact that methotrexate use is associated with malabsorption. The objective of this study was to assess for vitamin B12 deficiency among patients with RA treated with methotrexate and folic acid. METHODS: This cross-sectional study included 50 patients with RA treated with methotrexate and folic acid and 49 patients with RA treated with other therapies. Patients were matched by age, sex, race, renal function, and disease activity. We compared plasma vitamin B12, methylmalonic acid, and homocysteine levels between these two groups utilizing quantitative and categorical analyses. RESULTS: Thirty-seven (74%) RA patients on methotrexate and folic acid had elevated plasma homocysteine levels compared with only 27 (55%) RA patients receiving other therapies (P < 0.05). The proportion of patients with low vitamin B12 and high methylmalonic acid levels did not differ between the two groups. CONCLUSIONS: Our data show high plasma homocysteine levels among RA patients treated with methotrexate and folic acid. While plasma vitamin B12 levels were similar between the two groups, high plasma homocysteine is also a sensitive marker of vitamin B12 deficiency. Additional studies should evaluate for the presence of clinical features of vitamin B12 deficiency and hyperhomocysteinemia among RA patients treated with methotrexate and folic acid.

On the Relationship between MMA Levels in Blood Products and Donor Sex, Age, and Donation Frequency.

As the aging process accelerates, the age structure of blood donors turns to older and even aged groups. Methylmalonic acid (MMA), a byproduct of propionate metabolism, may be upregulated in the serum of older adults. As a mediator of chronic disease and tumor progression, the MMA content in blood products has become the focus of research. Absolute concentrations of MMA in blood products were determined based on the liquid chromatography-tandem mass spectrometry, so as to analyze how they were affected by donors' age, sex, and frequency of blood donation. The MMA content in leukocyte-depleted suspended red blood cell (lds-RBC) was significantly higher than that in fresh plasma (p<0.0001). The MMA content among five age groups showed no difference in either fresh plasma or lds-RBCs. The MMA content in fresh plasma was similar in the parameters of the sex, whereas that in lds-RBCs was higher in males than that in females (p=0.035). There were no significant differences in MMA content when it comes to different frequencies of blood donors in either fresh plasma or lds-RBCs. Additionally, there was no significant difference or clear trend in the rate of elevated plasma MMA levels among different sexes, age groups, and blood donation frequency groups. MMA in the blood products from donors in China does not compromise the safety of blood transfusions for cancer patients. Nevertheless, there is a need to focus on MMA levels in Chinese and to develop race-specific and age-specific normal reference ranges.

Aging-accumulated methylmalonic acid serum levels at breast cancer diagnosis are not associated with distant metastases.

PURPOSE: Recent evidence suggests that age-accumulated methylmalonic acid (MMA) promotes breast cancer progression in mice. This study aims to investigate the association between baseline serum MMA concentrations in patients with breast cancer and the development of subsequent distant metastases. METHODS: We included 32 patients with early Luminal B-like breast cancer (LumB, median age 62.4y) and 52 patients with early triple-negative breast cancer (TNBC, median age 50.5y) who developed distant metastases within 5 years. They were matched to an equal number of early breast cancer patients (median age 62.2y for LumB and 50.5y for TNBC) who did not develop distant metastases with at least 5 years of follow-up. RESULTS: Baseline serum MMA levels at breast cancer diagnosis showed a positive correlation with age (P < 0.001) and a negative correlation with renal function and vitamin B12 (all P < 0.02), but no statistical association was found with BMI or tumor stage (P > 0.6). Between matched pairs, no significant difference was observed in MMA levels, after adjusting for kidney function and age (P = 0.19). Additionally, in a mouse model, a significant decline in MMA levels was observed in the tumor-bearing group compared to the group without tumors before and after tumor establishment or at identical times for the control group (P = 0.03). CONCLUSION: Baseline serum MMA levels in patients with breast cancer are not correlated with secondary distant metastasis. Evidence in the mouse model suggests that the presence of a tumor perturbates MMA levels.

Association between dietary macronutrient composition and plasma one-carbon metabolites and B-vitamin cofactors in patients with stable angina pectoris.

Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.

The MMACHC variant c.158T>C: Mild clinical and biochemical phenotypes and marked hydroxocobalamin response in cblC patients.

Mutations in MMACHC cause cobalamin C disease (cblC, OMIM 277400), the commonest inborn error of vitamin B12 metabolism. In cblC, deficient activation of cobalamin results in methylcobalamin and adenosylcobalamin deficiency, elevating methylmalonic acid (MMA) and total plasma homocysteine (tHcy). We retrospectively reviewed the medical files of seven cblC patients: three compound heterozygotes for the MMACHC (NM_015506.3) missense variant c.158T>C p.(Leu53Pro) in trans with the common pathogenic mutation c.271dupA (p.(Arg91Lysfs*14), "compounds"), and four c.271dupA homozygotes ("homozygotes"). Compounds receiving hydroxocobalamin intramuscular injection monotherapy had age-appropriate psychomotor performance and normal ophthalmological examinations. In contrast, c.271dupA homozygotes showed marked psychomotor retardation, retinopathy and feeding problems despite penta-therapy (hydroxocobalamin, betaine, folinic acid, l-carnitine and acetylsalicylic acid). Pretreatment levels of plasma and urine MMA and tHcy were higher in c.271dupA homozygotes than in compounds. Under treatment, levels of the compounds approached or entered the reference range but not those of c.271dupA homozygotes (tHcy: compounds 9.8-32.9 µM, homozygotes 41.6-106.8 (normal (N) < 14); plasma MMA: compounds 0.14-0.81 µM, homozygotes, 10.4-61 (N < 0.4); urine MMA: compounds 1.75-48 mmol/mol creatinine, homozygotes 143-493 (N < 10)). Patient skin fibroblasts all had low cobalamin uptake, but this was milder in compound cells. Also, the distribution pattern of cobalamin species was qualitatively different between cells from compounds and from homozygotes. Compared to the classic cblC phenotype presented by c.271dupA homozygous patients, c.[158T>C];[271dupA] compounds had mild clinical and biochemical phenotypes and responded strikingly to hydroxocobalamin monotherapy.

The association between methylmalonic acid, a biomarker of mitochondrial dysfunction, and risk of prostate cancer.

BACKGROUND: The aim of the study was to investigate the association between methylmalonic acid (MMA), a biomarker of mitochondrial dysfunction, and the risk of prostate cancer (PCa). METHODS AND MATERIALS: The relevant data were collected from the National Health and Nutrition Examination Survey (NHANES). Weighted univariable and multivariable logistic regression analyses were performed to investigate the association between MMA and risk of PCa. A stratified analysis was also carried out. The dose-response relationship was elucidated by conducting a restricted cubic spline function. RESULTS: A total of 2451 participants were included, of which 95 were PCa participants. The fully-adjusted model 2 constructed by weighted multivariable logistic regression analysis showed that the risk of PCa decreased by 53% when every MMA unit was added [OR: 0.47 (0.22-1.00), P = 0.049]. And a decrease in PCa risk was associated with a higher MMA level in MMA subgroups [OR: 0.34 (0.15-0.82), P = 0.02]. The results from a stratified analysis showed that participants in subgroups of other race, BMI (> 30 kg/m2), smoking (former and now), and hypertension (yes), an increase in every MMA unit was linked to a decrease in PCa risk. MMA and the risk of PCa were negatively correlated in a linear manner. CONCLUSION: It was discovered in the study that an increase in MMA level is connected to a decrease in PCa risk. The serum MMA level may be helpful in assessing PCa risk.

Knock-Out of Retrovirus Receptor Gene Tva in the Chicken Confers Resistance to Avian Leukosis Virus Subgroups A and K and Affects Cobalamin (Vitamin B12)-Dependent Level of Methylmalonic Acid.

The chicken Tva cell surface protein, a member of the low-density lipoprotein receptor family, has been identified as an entry receptor for avian leukosis virus of classic subgroup A and newly emerging subgroup K. Because both viruses represent an important concern for the poultry industry, we introduced a frame-shifting deletion into the chicken tva locus with the aim of knocking-out Tva expression and creating a virus-resistant chicken line. The tva knock-out was prepared by CRISPR/Cas9 gene editing in chicken primordial germ cells and orthotopic transplantation of edited cells into the testes of sterilized recipient roosters. The resulting tva -/- chickens tested fully resistant to avian leukosis virus subgroups A and K, both in in vitro and in vivo assays, in contrast to their susceptible tva +/+ and tva +/- siblings. We also found a specific disorder of the cobalamin/vitamin B12 metabolism in the tva knock-out chickens, which is in accordance with the recently recognized physiological function of Tva as a receptor for cobalamin in complex with transcobalamin transporter. Last but not least, we bring a new example of the de novo resistance created by CRISPR/Cas9 editing of pathogen dependence genes in farm animals and, furthermore, a new example of gene editing in chicken.

Cobalamin and folate status in women during early pregnancy in Bhaktapur, Nepal.

The demand for cobalamin (vitamin B12) and folate is increased during pregnancy, and deficiency during pregnancy may lead to complications and adverse outcomes. Yet, the status of these micronutrients is unknown in many populations. We assessed the concentration of cobalamin, folate and their functional biomarkers, total homocysteine (tHcy) and methylmalonic acid (MMA), in 561 pregnant women enrolled in a community-based randomised controlled trial in Bhaktapur, Nepal. Plasma concentrations of cobalamin, folate, tHcy and MMA were measured and a combined indicator of vitamin B12 status (3cB12) was calculated. We report mean or median concentrations and the prevalence of deficiency according to commonly used cut-offs, and assessed their association with indicators of socio-economic status, and maternal and dietary characteristics by linear regression. Among the women at gestational week less than 15, deficiencies of cobalamin and folate were seen in 24 and 1 %, respectively. Being a vegetarian was associated with lower plasma cobalamin, and a higher socio-economic status was associated with a better micronutrient status. We conclude that cobalamin deficiency defined by commonly used cut-offs was common in Nepalese women in early pregnancy. In contrast, folate deficiency was rare. As there is no consensus on cut-off points for vitamin B12 deficiency during pregnancy, future studies are needed to assess the potential functional consequences of these low values.

Genetic variants modify the associations of concentrations of methylmalonic acid, vitamin B-12, vitamin B-6, and folate with bone mineral density.

BACKGROUND: Elevated plasma homocysteine has been found to be associated with an increased risk of osteoporosis, especially hip and vertebral fractures. The plasma concentration of homocysteine is dependent on the activities of several B vitamin-dependent enzymes, such as methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), methionine synthase reductase (MTRR), and cystathionine ß-synthase (CBS). OBJECTIVES: We investigated whether genetic variants in some of the genes involved in 1 carbon metabolism modify the association of B vitamin-related measures with bone mineral density (BMD) and strength. METHODS: We measured several B vitamins and biomarkers in participants of the Framingham Offspring Study, and performed analyses of methylmalonic acid (MMA) continuously and <210 nmol/L; pyridoxal-5'-phosphate; vitamin B-12 continuously and ≥258 pmol/L; and folate. The outcomes of interest included areal and volumetric BMD, measured by DXA and quantitative computed tomography (QCT), respectively. We evaluated associations between the bone measures and interactions of single nucleotide polymorphism with a B vitamin or biomarker in Framingham participants (n = 4310 for DXA and n = 3127 for QCT). For analysis of DXA, we validated the association results in the B-PROOF cohort (n = 1072). Bonferroni-corrected locus-wide significant thresholds were defined to account for multiple testing. RESULTS: The interactions between rs2274976 and vitamin B-12 and rs34671784 and MMA <210 nmol/L were associated with lumbar spine BMD, and the interaction between rs6586281 and vitamin B-12 ≥258 pmol/L was associated with femoral neck BMD. For QCT-derived traits, 62 interactions between genetic variants and B vitamins and biomarkers were identified. CONCLUSIONS: Some genetic variants in the 1-carbon methylation pathway modify the association of B vitamin and biomarker concentrations with bone density and strength.  These interactions require further replication and functional validation for a mechanistic understanding of the role of the 1-carbon metabolism pathway on BMD and risks of fracture.

Maternal vitamin B12 deficiency and perinatal outcomes in southern India.

BACKGROUND: Vitamin B12 deficiency during pregnancy has been associated with adverse maternal and infant health outcomes. Few prospective studies have investigated vitamin B12 status early in pregnancy, and its links to infant vitamin B12 status, particularly in India where the burden of vitamin B12 deficiency is estimated to be the highest globally. The objective of this study was to examine the associations of maternal vitamin B12 biomarkers with neonatal vitamin B12 status. METHODS: Pregnant women (~12 weeks' gestation) were enrolled in a perinatal cohort study in Bangalore, India. Total vitamin B12, methylmalonic acid (MMA), and homocysteine concentrations were evaluated in maternal samples at enrollment and in neonates at birth using cord blood. Linear and binomial regression models were used to evaluate the associations of maternal vitamin B12 biomarkers with neonatal vitamin B12 status and perinatal outcomes. RESULTS: A total of 63.2% of women had vitamin B12 deficiency (<148 pmol/L), 87.2% had vitamin B12 insufficiency (<221 pmol/L), and 47.3% had impaired vitamin B12 status (vitamin B12<148 pmol/L and MMA>0.26µmol/L) at enrollment; 40.8% of neonates had vitamin B12 deficiency, 65.6% were insufficiency, and 38.1% had impaired vitamin B12 status at birth. Higher maternal vitamin B12 concentrations at enrollment were associated with increased neonatal vitamin B12 concentrations (ß(SE): 0.40 (0.05); p<0.0001) and lower risk of neonatal vitamin B12 deficiency (Risk Ratio [RR]: 0.53; 95% CI: [0.43, 0.65]; p<0.0001). Maternal vitamin B12 deficiency (RR: 1.97 [1.43, 2.71]; p<0.001), insufficiency (RR: 2.18 [1.23, 3.85]; p = 0.007), and impaired vitamin B12 status (RR: 1.49 [1.13, 1.97]; p = 0.005) predicted a two-fold increase in the risk of neonatal vitamin B12 deficiency at birth. CONCLUSIONS: The prevalence of vitamin B12 deficiency was high early in pregnancy and predicted neonatal vitamin B12 status. Future research is needed to determine the role of vitamin B12 in the development of pregnancy and infant outcomes, and to inform screening and interventions to improve maternal and child health.

Cardiovascular manifestations of intermediate and major hyperhomocysteinemia due to vitamin B12 and folate deficiency and/or inherited disorders of one-carbon metabolism: a 3.5-year retrospective cross-sectional study of consecutive patients.

BACKGROUND: The association of moderate hyperhomocysteinemia (HHcy) (15-30 µmol/L) with cardiovascular diseases (CVD) has been challenged by the lack of benefit of vitamin supplementation to lowering homocysteine. Consequently, the results of interventional studies have confused the debate regarding the management of patients with intermediate/severe HHcy. OBJECTIVE: We sought to evaluate the association of intermediate (30-100 µmol/L) and severe (>100 µmol/L) HHcy related to vitamin deficiencies and/or inherited disorders with CVD outcomes. METHODS: We performed a retrospective cross-sectional study on consecutive patients who underwent a homocysteine assay in a French University Regional Hospital Center. Patients with CVD outcomes were assessed for vitamin B12, folate, Hcy, methylmalonic acid, and next-generation clinical exome sequencing. RESULTS: We evaluated 165 patients hospitalized for thromboembolic and other cardiovascular (CV) manifestations among 1006 patients consecutively recruited. Among them, 84% (138/165) had Hcy >30 µmol/L, 27% Hcy >50 µmol/L (44/165) and 3% Hcy >100 µmol/L (5/165). HHcy was related to vitamin B12 and/or folate deficiency in 55% (87/165), mutations in one or more genes of one-carbon and/or vitamin B12 metabolisms in 11% (19/165), and severe renal failure in 15% (21/141) of the studied patients. HHcy was the single vascular risk retrieved in almost 9% (15/165) of patients. Sixty % (101/165) of patients received a supplementation to treat HHcy, with a significant decrease in median Hcy from 41 to 17 µmol/L (IQR: 33.6-60.4 compared with 12.1-28). No recurrence of thromboembolic manifestations was observed after supplementation and antithrombotic treatment of patients who had HHcy as a single risk, after ∼4 y of follow-up. CONCLUSION: The high frequency of intermediate/severe HHcy differs from the frequent moderate HHcy reported in previous observational studies of patients with pre-existing CVD. Our study points out the importance of diagnosing and treating nutritional deficiencies and inherited disorders to reverse intermediate/severe HHcy associated with CVD outcomes.

COVID-19: A methyl-group assault?

The socio-economic implications of COVID-19 are devastating. Considerable morbidity is attributed to 'long-COVID' - an increasingly recognized complication of infection. Its diverse symptoms are reminiscent of vitamin B12 deficiency, a condition in which methylation status is compromised. We suggest why SARS-CoV-2 infection likely leads to increased methyl-group requirements and other disturbances of one-carbon metabolism. We propose these might explain the varied symptoms of long-COVID. Our suggested mechanismmight also apply to similar conditions such as myalgic encephalomyelitis/chronic fatigue syndrome. The hypothesis is evaluable by detailed determination of vitamin B12and folate status, including serum formate as well as homocysteine and methylmalonic acid, and correlation with viral and host RNA methylation and symptomatology. If confirmed, methyl-group support should prove beneficial in such individuals.

Cross-sectional association between vitamin B12 status and probable postpartum depression in Indian women.

BACKGROUND: Vitamin B12 is an essential micronutrient for neurological function, as it leads to the regeneration of methionine from homocysteine, which is precursor of biologically active molecule S-Adenosyl Methionine (SAM). Pregnancy is a state of increased demand and delayed postpartum repletion of nutrients may predispose women to depression. METHODS: We included women who visited the hospital at 6-weeks postpartum for a regular checkup. Inclusion criteria were age (18-50 years), and willingness to donate venous sample for analysis. Exclusion criteria included previous history of mood disorders or antidepressant medication use, and any systemic illness like hypothyroidism, epilepsy, diabetes, and hypertension. Based on EPDS score of 10 as a cutoff, 217 women with probable postpartum depression (PPD) and equal number of age and BMI matched controls were included. Plasma total vitamin B12, holotranscobalamin (holotc), homocysteine (hcy), methyl malonic acid (MMA), 5-methyl tetrahydrofolate (THF), SAM and serotonin levels were estimated using commercially available ELISA kits. Combined B12 (cB12) score was calculated from study parameters. Multivariate analysis was performed to assess the risk of probable postpartum depression. RESULTS: Total vitamin B12 and combined B12 score were found to be significantly lower (p = 0.001) and MMA (p = 0.002) and 5-methyl THF (p < 0.001) levels were higher in women with probable depression than women without probable PPD. Women in the lowest vitamin B12 quartile had 4.53 times higher likelihood of probable postpartum depression (p < 0.001). Multivariate analysis demonstrated that decreasing vitamin B12 (OR = 0.394; 95% CI: 0.189-0.822) and cB12 (OR = 0.293; 95% CI: 0182-0.470) and increasing MMA (OR = 2.14; 95% CI: 1.63-2.83) and 5-methyl THF levels (OR = 3.29; 95% CI: 1.59-6.83) were significantly associated with the risk of probable PPD. CONCLUSION: Low vitamin B12 may contribute to depressive symptoms in vulnerable postpartum period.

Plasma 3-hydroxyisobutyrate (3-HIB) and methylmalonic acid (MMA) are markers of hepatic mitochondrial fatty acid oxidation in male Wistar rats.

OBJECTIVE: Discovery of specific markers that reflect altered hepatic fatty acid oxidation could help to detect an individual's risk of fatty liver, type 2 diabetes and cardiovascular disease at an early stage. Lipid and protein metabolism are intimately linked, but our understanding of this crosstalk remains limited. METHODS: In male Wistar rats, we used synthetic fatty acid analogues (3-thia fatty acids) as a tool to induce hepatic fatty acid oxidation and mitochondrial biogenesis, to gain new insight into the link between fatty acid oxidation, amino acid metabolism and TCA cycle-related intermediate metabolites in liver and plasma. RESULTS: Rats treated with 3-thia fatty acids had 3-fold higher hepatic, but not adipose and skeletal muscle, expression of the thioesterase 3-hydroxyisobutyryl-CoA hydrolase (Hibch), which controls the formation of 3-hydroxyisobutyrate (3-HIB) in the valine degradation pathway. Consequently, 3-thia fatty acid-stimulated hepatic fatty acid oxidation and ketogenesis was accompanied by decreased plasma 3-HIB and increased methylmalonic acid (MMA) concentrations further downstream in BCAA catabolism. The higher plasma MMA corresponded to higher MMA-CoA hydrolase activity and hepatic expression of GTP-specific succinyl-CoA synthase (Suclg2) and succinate dehydrogenase (Sdhb), and lower MMA-CoA mutase activity. Plasma 3-HIB correlated positively to plasma and hepatic concentrations of TAG, plasma total fatty acids, plasma NEFA and insulin/glucose ratio, while the reverse correlations were seen for MMA. CONCLUSION: Our study provides new insight into TCA cycle-related metabolic changes associated with altered hepatic fatty acid flux, and identifies 3-HIB and MMA as novel circulating markers reflective of mitochondrial ß-oxidation in male Wistar rats.

Delineating the clinical spectrum of isolated methylmalonic acidurias: cblA and mut.

INTRODUCTION: Long-term outcome is postulated to be different in isolated methylmalonic aciduria caused by mutations in the MMAA gene (cblA type) compared with methylmalonyl-CoA mutase deficiency (mut), but case definition was previously difficult. METHOD: Cross-sectional analysis of data from the European Registry and Network for Intoxication type Metabolic Diseases (Chafea no. December 1, 2010). RESULTS: Data from 28 cblA and 95 mut patients in most cases confirmed by mutation analysis (including 4 new mutations for cblA and 19 new mutations for mut). Metabolic crisis is the predominant symptom leading to diagnosis in both groups. Biochemical disturbances during the first crisis were similar in both groups, as well as the age at diagnosis. Z scores of body height and body weight were similar in both groups at birth, but were significantly lower in the mut group at the time of last visit. Glomerular filtration rate was significantly higher in cblA; and as a consequence, chronic renal failure and related complications were significantly less frequent and renal function could be preserved even in older patients. Neurological complications were predominantly found in the mut subgroup. Methylmalonic acidemia (MMA) levels in urine and plasma were significantly lower in cblA. 27/28 cblA patients were reported to be responsive to cobalamin, only 86% of cblA patients were treated with i.m. hydroxocobalamin. In total, 73% of cblA and 98% of mut patients followed a calculated diet with amino acid supplements in 27% (cblA) and 69% (mut). During the study interval, six patients from the mut group died, while all cblA patients survived. CONCLUSION: Although similar at first, cblA patients respond to hydroxocobalamin treatment, subsequently show significantly lower levels of MMA and a milder course than mut patients.

Test utilization for the diagnosis of vitamin B12 and folate deficiency in local clinics in Korea.

BACKGROUND: Current guidelines pertaining to diagnosing macrocytic anemia in association with vitamin B12 and folate deficiency recommend that vitamin B12, folate, homocysteine, and methylmalonic acid assays should be assessed concurrently due to their close relationship in metabolism. We aimed to investigate the completion of these assays in local clinics and hospitals without in-house clinical laboratories in Korea. METHODS: We retrospectively reviewed data from the laboratory information system between September 25, 2017, and June 30, 2019, to investigate usage rates of vitamin B12, folate, homocysteine, and methylmalonic acid assays in patients with macrocytic anemia. RESULTS: During the study period, 14 894 Korean adults among 109 524 (13.6%) total hemoglobin-tested subjects underwent concurrent erythrocyte mean corpuscular volume (MCV) tests. Among these 14,894 adults, 265 (1.2%) from 94 local clinics or hospitals without in-house clinical laboratories in Korea had macrocytic anemia. Furthermore, among these 265 adults, only one woman underwent serum vitamin B12 and folate assay and one man underwent serum homocysteine testing during the study period. No patients among the 265 individuals with macrocytic anemia received erythrocyte folate or methylmalonic acid testing (with either serum, plasma, random urine, or 24-hour collected urine). CONCLUSIONS: The results of this study provide basic information regarding utilization rates of assays in association with vitamin B12 and folate deficiency. Making more data available is expected to improve rates of testing in patients with macrocytic anemia in local clinics and hospitals without in-house clinical laboratories in Korea.