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Background. Pathological changes in vitamin B12 levels are a common laboratory finding. The increase in serum vitamin B12 levels is termed B12 hypervitaminemia, often perceived as a benign disorder, leading to its underestimation. Objective.This paper aims to examine the potential pathogenetic mechanisms and the association of vitamin B12 excess with various diseases. Methodology. A literature search was conducted using the PubMed, DOAJ, and Google Scholar databases. The search was focused on original articles, review papers, and reference lists published in English since 2000. Results. Increased vitamin B12 levels are encountered in hematological disorders, solid tumors, renal and hepatic diseases, as well as inflammatory conditions. Vitamin B12 supplements increase the levels and can exacerbate underlying pathological conditions. The pathophysiology involves disturbances in the biology and metabolism of vitamin B12 and its carrier proteins. Falsely elevated values can arise due to interferences in quantitative assays. Elevated vitamin B12 may represent an incidental finding, accompany findings of underlying disease, and coexist with manifestations of functional deficiency. Conclusion. Elevated vitamin B12 may serve as an early indicator for the diagnosis and monitoring of serious diseases. Understanding the underlying pathogenetic mechanisms and establishing diagnostic algorithms are crucial areas for future research. [ABSTRACT FROM AUTHOR]

Cobalamin or vitamin B12 (B12) is a cofactor for methionine synthase and methylmalonyl-CoA mutase, two enzymes implicated in key pathways for cell proliferation: methylation, purine synthesis, succinylation and ATP production. Ensuring these functions in cancer cells therefore requires important cobalamin needs and its uptake through the transcobalamin II receptor (TCII-R). Thus, both the TCII-R and the cobalamin-dependent metabolic pathways constitute promising therapeutic targets to inhibit cancer development. However, the link between cobalamin and solid cancers is not limited to cellular metabolism, as it also involves the circulating transcobalamins I and II (TCI or haptocorrin and TCII) carrier proteins, encoded by TCN1 and TCN2, respectively. In this respect, elevations of B12, TCI and TCII concentrations in plasma are associated with cancer onset and relapse, and with the presence of metastases and worse prognosis. In addition, TCN1 and TCN2 overexpressions are associated with chemoresistance and a proliferative phenotype, respectively. Here we review the involvement of cobalamin and transcobalamins in cancer diagnosis and prognosis, and as potential therapeutic targets. We further detail the relationship between cobalamin-dependent metabolic pathways in cancer cells and the transcobalamins' abundancies in plasma and tumors, to ultimately hypothesize screening and therapeutic strategies linking these aspects.

BackgroundReducing meat consumption is often advised; however, inadvertent nutritional deficiencies during pregnancy may result in residual neurodevelopmental harms to offspring. This study assessed possible effects of maternal diets in pregnancy on adverse substance use among adolescent offspring.MethodsPregnant women and their 13-year-old offspring taking part in a prospective birth cohort study, the Avon Longitudinal Study of Parents and Children (ALSPAC), provided Food Frequency Questionnaire data from which dietary patterns were derived using principal components analysis. Multivariable logistic regression models including potential confounders evaluated adverse alcohol, cannabis, and tobacco use of the children at 15 years of age.ResultsLower maternal meat consumption was associated with greater problematic substance use among 15-year-old offspring in dose-response patterns. Comparing never to daily meat consumption after adjustment, risks were greater for all categories of problem substance use: alcohol, odds ratio OR = 1.75, 95% CI = (1.23, 2.56), p

Vitamin B12 is one of the most important B vitamins. This vitamin has an important role in cellular metabolism and is also associated with folate and vitamin B6 metabolism. Vitamin B12 deficiency occurs as a result of some diseases, the use of certain medications, or inadequate nutrition. It primarily affects the elderly and women, but is also common among the pediatric population. The B12 deficiency mostly affects the functions of the nervous and hematopoietic systems but it can also affect the skin, heart, bones, and eyes. The treatment of vitamin B12 deficiency includes oral or intramuscular vitamin B12 supplementation according to different treatment regimens. [ABSTRACT FROM AUTHOR]

Elevated homocysteine (Hcy) levels (≥15 μmol/L) in the elderly are frequently associated with a higher risk of cardiovascular disease and cognitive decline. Several studies have already shown an Hcy-lowering effect of B vitamin supplementation in cohorts deficient in these nutrients. The aim of this randomized, double-blinded 12-week intervention study was to investigate whether Hcy levels in healthy elderly subjects (75.4±4.5 years, n=133) could be lowered with a micronutrient supplement (i.e., 400 μg folic acid, 100 μg cobalamin). Difference in mean initial Hcy levels between intervention (17.6±7.1 μmol/L, n=65) and placebo group (18.9±6.1 μmol/L, n=68) was not significant. The prevalence of cobalamin and folate deficiency in the total study population was low: 27% had serum-cobalamin levels ≤150 pmol/L, 12% holo-transcobalamin (Holo-TC) levels ≤50 pmol/L, 13% low cobalamin status using the aggregated cobalamin marker 4cB12 and 10% red blood cell (RBC) folate ≤570 nmol/L. Nevertheless, the treated subjects still showed improved cobalamin and folate biostatus (serum cobalamin Δt 12 -t 0 : 63±48 pmol/L; Holo-TC Δt 12 -t 0 : 17±19 pmol/L; RBC folate Δt 12 -t 0 : 326±253 nmol/L) and Hcy levels (Δt 12 -t 0 : -3.6±5.7 μmol/L). The effects were statistically significant compared to the placebo group with p=0.005 (serum cobalamin), p=0.021 (Holo-TC), p=0.014 (RBC-folate) and p<0.001 (Hcy). The Hcy-lowering effect was dependent on the initial Hcy levels (p<0.001). Our findings suggest that elevated Hcy levels in elderly subjects can be lowered regardless of the initial cobalamin and folate biostatus.

Cobalamin or vitamin B12 (B12) is a cofactor for methionine synthase and methylmalonyl-CoA mutase, two enzymes implicated in key pathways for cell proliferation: methylation, purine synthesis, succinylation and ATP production. Ensuring these functions in cancer cells therefore requires important cobalamin needs and its uptake through the transcobalamin II receptor (TCII-R). Thus, both the TCII-R and the cobalamin-dependent metabolic pathways constitute promising therapeutic targets to inhibit cancer development. However, the link between cobalamin and solid cancers is not limited to cellular metabolism, as it also involves the circulating transcobalamins I and II (TCI or haptocorrin and TCII) carrier proteins, encoded by TCN1 and TCN2, respectively. In this respect, elevations of B12, TCI and TCII concentrations in plasma are associated with cancer onset and relapse, and with the presence of metastases and worse prognosis. In addition, TCN1 and TCN2 overexpressions are associated with chemoresistance and a proliferative phenotype, respectively. Here we review the involvement of cobalamin and transcobalamins in cancer diagnosis and prognosis, and as potential therapeutic targets. We further detail the relationship between cobalamin-dependent metabolic pathways in cancer cells and the transcobalamins’ abundancies in plasma and tumors, to ultimately hypothesize screening and therapeutic strategies linking these aspects.

Background/objectivesA common polymorphism, C776G, in the plasma B12 transport protein transcobalamin (TC), encodes for either proline or arginine at codon 259. This polymorphism may affect the affinity of TC for B12 and subsequent delivery of B12 to tissues.Subjects/methodsTC genotype and its associations with indicators of B12 status, including total B12, holotranscobalamin (holoTC), methylmalonic acid and homocysteine, were evaluated in a cohort of elderly Latinos (N=554, age 60-93 years) from the Sacramento Area Latino Study on Aging (SALSA).ResultsThe distribution of TC genotypes was 41.3% homozygous reference (776CC) and 11.6% homozygous variant (776GG). No differences between the homozygous genotypes were observed in total B12, holoTC, methylmalonic acid or homocysteine. The holoTC/total B12 ratio was lower in the 776GG group compared with the 776CC group (P=0.04). Significant interactions of TC genotype with total B12 (P=0.04) and with holoTC (P< or =0.03) were observed such that mean homocysteine concentrations and the odds ratios for hyperhomocysteinemia (>13 micromol/l) were higher in the 776CC subjects compared with all carriers of the G allele (776CG and 776GG combined) when total B12 (

Transcobalamin (TCN1) is a vitamin B12 (cobalamin)-binding protein that regulates cobalamin homeostasis. Recent studies and bioinformatic analyses have found that TCN1 is highly expressed in cancer tissues and is associated with tumour aggressiveness and poor prognosis. The present study aimed to detect TCN1 as a novel biomarker for prognosis and chemosensitivity of colon cancer. Next-generation sequencing showed that TCN1 was one of several upregulated mRNAs in colon cancer, which was verified by further bioinformatics analyses. Western blotting (n = 9) and quantitative real time polymerase chain reaction (qRT-PCR, n = 30) revealed that TCN1 was highly expressed in colon cancer tissues at both the protein and mRNA level. A total of 194 cases of colon cancer were examined by immunohistochemistry and revealed that TCN1 expression level was related to advanced stages (P < 0.005). Kaplan–Meier analysis verified that patients with lower TCN1 expression usually had longer overall survival (P = 0.008). In addition, TCN1 was highly expressed in pulmonary metastatic tumour tissues (n = 37, P = 0.025) and exhibited higher levels in right-sided colon cancer than in left-sided colon cancer (P = 0.029). TCN1 expression in specimens that had received neoadjuvant chemotherapy decreased compared with that in colonoscopy biopsy tissues (n = 42, P = 0.009). Further bioinformatics analyses verified that apoptosis pathways might have a role in high TCN1 expression. All the studies revealed that TCN1 expression in colon cancer was significantly associated with malignant biological behaviour. Therefore, TCN1 could be used as a novel biomarker for colon cancer aggressiveness and prognosis and might also be a potential biomarker for predicting neoadjuvant chemosensitivity. [ABSTRACT FROM AUTHOR]

High cobalamin levels have previously been associated with short-term cancer risk, including lung cancer. We explored whether levels of cobalamin and/or its binding proteins are useful as a diagnostic tool in patients suspected of non-small cell lung cancer. We included 889 patients referred for fast-track diagnosis of lung cancer to Aarhus University Hospital, Denmark. We analyzed plasma concentrations of cobalamin, transcobalamin, holotranscobalamin and haptocorrin. Information on lung cancer diagnosis was retrieved from a national database. The study cohort showed levels above reference intervals for cobalamin 12%, holotranscobalamin 25%, transcobalamin 9% and haptocorrin 36% (all p-values <.05). We observed no difference in cobalamin or holotranscobalamin levels when comparing patients diagnosed with non-small cell lung cancer (n = 161, 18%) to patients without lung cancer (n = 742, 80%), while transcobalamin showed minor differences. Haptocorrin was significantly higher in those with cancer, mainly among patients with adenocarcinoma (n = 94). A comparison of patients with the highest vs. lowest quartile levels of haptocorrin yielded an adjusted odds ratio for adenocarcinoma of 2.39 (95% confidence interval: 1.26-4.55). However, ROC curve analyzes showed haptocorrin (AUC = 0.55) and total transcobalamin (AUC = 0.56) to be poor diagnostic markers for lung cancer. A high proportion of patients suspected for non-small cell lung cancer showed increased levels of cobalamin-binding proteins. We thereby confirm the association between non-small cell lung cancer and high cobalamin levels and found that haptocorrin was the major underlying factor causing high cobalamin levels. However, none of these biomarkers were of diagnostic use among patients referred for suspected lung cancer. [ABSTRACT FROM AUTHOR]

Background: Vitamin B12 deficiency is a common disorder. In circulation, vitamin B12 is bound to transcobalamin (holotranscobalamin), which is considered the active form of cobalamin. The objective of this study was to evaluate the analytical performance of the Roche Elecsys Active B12 immunoassay. Methods: Limit of quantification and linearity were assessed according to CLSI EP17-A2 and EP-6A guidelines. Precision and bias of Roche Active B12 test against Architect ci8200 (Abbott) were performed according to CLSI EP-5 A3 guideline at three European laboratories. Precision requirements were set at <4% for within-run precision and <15% for intermediate precision. Requirements for method comparison were set at a slope of 1.00 ± 20%. In addition, 95% reference interval was conducted in European adults according to CLSI-EP28 guideline. Results: The assay was shown to be linear and precise and met the requirements. Lot-to-lot variation and lab-to-lab variation both were ≤4%. Method comparison with Abbott Architect showed a significant bias of 9 pmol/L, which increases to up to 23 pmol/L around the current medical decision point. The 95% reference interval of the Roche Elecsys Active B12 test was determined at 37–188 pmol/L. Conclusion: Although Roche Elecsys Active B12 immunoassay met the requirements, this test has a positive bias of 9 pmol/L, which led to an increase in lower limit of reference interval compared with Abbott test. This test first needs to be clinically validated before it can be applied as a first-line screening test in the diagnosis of vitamin B12 deficiency. [ABSTRACT FROM AUTHOR]

Summary Background & aims Bariatric surgery increases the risk of micronutrient deficiencies, including vitamin B12 (B12) deficiency. We analysed early changes in biomarkers of B12 status following bariatric surgery. Methods We prospectively included adult patients (n = 27) referred for either Roux-en-Y Gastric Bypass (RYGB) (n = 19) or Sleeve Gastrectomy (SG) (n = 8). Blood samples were drawn before surgery and 2 and 6 months following surgery for measurement of B12, holotranscobalamin (holoTC), and methylmalonic acid (MMA). The B12 absorption capacity was estimated from the increase in plasma holoTC two days after a standardised oral B12 challenge. Results B12 status decreased following both RYBG and SG. While a decrease in plasma B12 was not evident until 6 months postoperatively, we observed a statistically significant decrease in plasma holoTC and increase in MMA already 2 months postoperatively. These changes were more pronounced at 6 months post surgery. Correspondingly, the B12 absorption capacity was decreased following surgery. Conclusions HoloTC and MMA were superior to B12 to detect early changes in B12 status following bariatric surgery. Our data challenge the current concept that liver B12 stores secure long-term maintenance of B12 status. They indicate that B12 treatment in pharmacological doses may be warranted immediately after surgery. [ABSTRACT FROM AUTHOR]

In humans, transport of food-derived cobalamin (vitaminB12) from the digestive system into the bloodstream involves three paralogous proteins: transcobalamin (TC), haptocorrin (HC), and intrinsic factor (IF). Each of these proteins contains two domains, an α-domain and a β-domain, which together form a cleft in which cobalamin binds. Zebrafish (Danio rerio) are thought to possess only a single cobalamin transport protein, referred to as Tcn2, which is a transcobalamin homolog. Here, we used CRISPR/Cas9 mutagenesis to create null alleles of tcn2 in zebrafish. Fish homozygous for tcn2-null alleles were viable and exhibited no obvious developmentally or behaviorally abnormal phenotypes. For this reason, we hypothesized that previously unidentified cobalamin-carrier proteins encoded in the zebrafish genome may provide an additional pathway for cobalamin transport. We identified genes predicted to code for two such proteins, Tcn-beta-a (Tcnba) and Tcn-beta-b (Tcnbb), which differ from all previously characterized cobalamin transport proteins as they lack the α-domain. These β-domain--only proteins are representative of an undescribed class of cobalamin- carrier proteins that are highly conserved throughout the ray-finned fishes. We observed that the genes encoding the three cobalamin transport homologs, tcn2, tcnba, and tcnbb, are expressed in unique spatial and temporal patterns in the developing zebrafish. Moreover, exogenously expressed recombinant Tcnba and Tcnbb bound cobalamin with high affinity, comparable with binding by full-length Tcn2. Taken together, our results suggest that this noncanonical protein structure has evolved to fully function as a cobalamin-carrier protein, thereby allowing for a compensatory cobalamin transport mechanism in the tcn2-/- zebrafish. [ABSTRACT FROM AUTHOR]

Metabolism of propionate in human subjects was studied using bolus administration of 1-13C-propionate i.v. or orally. The study population consisted of five patients with propionic acidemia (PA), eight with methylmalonic acidemia (MMA; four responsive to vitamin B12), one each with multiple carboxylase deficiency and transcobalamin-II deficiency, and five healthy volunteers. Concentrations of 1-13C-propionate were measured in blood in three patients with PA, two with MMA, and two controls. Breath samples were obtained at intervals during 3 h after the dose, isotopic enrichment of 13CO2 was measured, and the cumulative percentage of recovery of 13C was calculated from the individual's predicted resting energy expenditure. Recovery of 13CO2 and half-time of 1-13C-propionate in PA were significantly less than normal. The same parameters in MMA were below normal, but significantly greater than in PA. Recovery of 13CO2 was well correlated with clinical severity in PA, but did not correlate in MMA. Differences between MMA and PA may indicate different distribution of propionate pools, differences in inducibility of residual enzyme activities, or an alternate pathway for decarboxylation of propionate available in MMA but not PA. Only one patient with PA demonstrated increased 13CO2 production during biotin treatment. In a B12-responsive MMA patient, no differences were noted within 2 d of initiating treatment with B12, but there was an increase in 13CO2 production after 4 mo. Recovery of 13CO2 was normal in the patient with transcobalamin-II deficiency before and after treatment with vitamin B12.(ABSTRACT TRUNCATED AT 250 WORDS)

It has been proposed that transcobalamin 2 (TCN2) and the transcobalamin 2 receptor (TCN2R) are associated with idiopathic recurrent spontaneous abortion (RSA). The aim of the present study was to investigate the impact of TCN2 rs1801198 and TCN2R rs2336573 polymorphism on RSA in a sample of Iranian population. This case-control study was done on 92 RSA patients and 93 normal, fertile women. Genotyping of the TCN2 rs1801198 and TCN2R rs2336573 variants was done by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The findings showed no significant association between the TCN2 rs1801198 and TCN2R rs2336573 polymorphisms and the risk/protection of RSA. Our results did not support an association between the TCN2 polymorphism and the risk of RSA in a sample of southeast Iranian population. Larger studies with different ethnicities are needed to evaluate the possible impact of TCN2 and TCN2R polymorphisms on the pathogenesis of RSA. Impact statement What is already known on this subject? Recurrent spontaneous abortion (RSA), a multifactorial condition, is one of the most common complications of pregnancy. It has been proposed that genetic polymorphisms play a role in the pathogenesis of RSA. Few studies have examined the association between TNC2 and TCN2R polymorphisms and the RSA risk and the findings were inconsistent. The aim of the current study was to determine the possible association between the TCN2 rs1801198 and TCN2R rs2336573 polymorphisms and the RSA in a sample of the southeast Iranian population. What do the results of the study add? The findings of the present case-control study did not support an association between the TCN2 rs1801198 and TCN2R rs2336573 polymorphisms and the risk of RSA in a sample of the Iranian population. What are the implications of these findings for clinical practice and future research? The findings of this study may provide a basis for future studies with larger sample sizes and different ethnicities on the role of TCN2 and TCN2R polymorphisms in the pathogenesis of RSA. [ABSTRACT FROM AUTHOR]

Background: Hypopharyngeal squamous cell carcinoma (HPSCC) is an aggressive head and neck squamous cell carcinoma with poor prognosis. Neoadjuvant chemotherapy (NACT) followed by concurrent chemoradiotherapy could provide better efficacy in HPSCC treatment. Identification of predictive biomarkers is critically needed to improve selection of patients who derive the most benefit from NACT. The aim of this study was to investigate whether transcobalamin I (TCN1) could be a novel predictive biomarker for NACT in HPSCC. Methods: We collected biopsy specimens from 102 patients with primary locally advanced HPSCC. Messenger RNA (mRNA) and protein expression levels of TCN1 were analyzed using quantitative polymerase chain reaction and immunohistochemistry, respectively. The relationship between TCN1 expression, chemotherapy sensitivity, and clinical outcome was assessed using univariate Kaplan–Meier survival analyses and multivariate analysis with covariate adjustments. Furthermore, we knocked down TCN1 by small interfering RNA (siRNA) in HPSCC cell FaDu, tested the effects of TCN1 knockdown on cisplatin toxicity by MTT assay, and detected cisplatin-induced apoptosis by Western blotting. Results: TCN1 expression was significantly lower in NACT-sensitive patients than non-sensitive patients at protein level (p=0.013) and mRNA level (p<0.001), indicating that low TCN1 expression predicts better NACT treatment response. Furthermore, TCN1 was an independent prognostic biomarker for both overall survival (p=0.047) and disease-free survival (p=0.05) in advanced HPSCC patients. In addition, in vitro experiments showed that genetic silencing of TCN1 using siRNA sensitized FaDu cells to cisplatin treatment with increased cell apoptosis. Conclusion: Low expression of TCN1 might be a novel prognostic biomarker for predicting NACT sensitivity and clinical outcome in local advanced HPSCC patients. [ABSTRACT FROM AUTHOR]

Background: Vitamin B-12 (cobalamin) deficiency may produce severe neurologic and hematologic manifestations. Approximately 20-25% of circulating cobalamin binds to transcobalamin 2 (TCN2), which is referred to as active vitamin B-12. The G allele of the TCN2 c.776G>C (rs1801198) polymorphism has been associated with a lower plasma concentration of holotranscobalamin. However, genotype association studies on rs1801198 have led to conflicting results regarding its influence on one-carbon metabolism (OCM) markers or its association with pathologic conditions. Objective: We assessed the association of rs1801198 genotypes with OCM marker concentrations and primary risks of congenital abnormalities, cancer, and Alzheimer disease. Design: We conducted a systematic review of the literature that was published from January 1966 to February 2017 and included all studies that assessed the association between rs1801198 and OCM markers or a pathologic condition. Results: Thirty-four studies met the inclusion criteria. Subjects with the rs1801198 GG genotype had significantly lower concentrations of holotranscobalamin [standardized mean difference (SMD): -0.445 (95% CI: -0.673, --0.217; P < 0.001); I² = 48.16% (95% CI: 0.00%, 78.10%; P = 0.07)] and higher concentrations of homocysteine (European descent only) [SMD: 0.070 (95% CI: 0.020, 0.120; P = 0.01); I² = 0.00% (95% CI: 0.00%, 49.59%; P = 0.73)] than did subjects with the rs1801198 CC genotype. The meta-analysis on the association between rs1801198 and methylmalonic acid (MMA) lacked statistical power. No significant difference was observed regarding cobalamin, folate, and red blood cell folate. No significant association was observed between rs1801198 and primary risks of congenital abnormalities, cancer, or Alzheimer disease. Conclusions: Meta-analysis results indicate an influence of rs1801198 on holotranscobalamin and homocysteine concentrations in European-descent subjects. In addition, well-designed and -powered studies should be conducted for assessing the association between rs1801198 and MMA and clinical manifestations that are linked to a decreased availability of cobalamin. This review was registered at www.crd.york.ac.uk/prospero as CRD42017058504. [ABSTRACT FROM AUTHOR]

The soluble transcobalamin receptor (sCD320) is present in cerebrospinal fluid and correlates with the dementia-related biomarkers phospho-tau and total-tau. Here we present data on the relation of sCD320 to Alzheimer’s disease and scores of cognitive tests. Lumbar cerebrospinal fluid samples from 42 pathologically-confirmed cases of Alzheimer’s disease and 25 non-demented controls were analyzed for sCD320 employing an in-house ELISA. The participants’ cognitive functions were tested using the Cambridge Cognition Examination (CAMCOG) and the Mini-Mental State Examination (MMSE). There was no significant difference in the median CSF sCD320 concentration between patients and controls. The median (2.5–97.5 percentiles) sCD320 for all participants (n = 67) was 15 (3–29) pmol/L. We observed a non-linear correlation between sCD320 and cognitive scores. Spearman’s correlation between sCD320 and total CAMCOG scores was 0.627 (n = 16,p = .009) for CAMCOG scores ≤27, and −0.293 (n = 39,p = .071) for CAMCOG scores ≥68. Spearman’s correlation between sCD320 and both the low (≤9) and high (≥16) total MMSE scores was 0.274, −0.363 (n = 18, 44),p = .272, .016, respectively. In conclusion, sCD320 cannot be employed as a biomarker for differentiating Alzheimer dementia patients from controls. Further studies are warranted to explore the non-linear correlations between sCD320 and scores of cognitive function. [ABSTRACT FROM PUBLISHER]

Objectives: The study aimed to investigate the association of Crohn's disease (CD) with transcobalamin II (TCN2) polymorphisms and serum homocysteine, folate, and vitamin B 12 levels. Methods: TCN2 (rs1801198, rs9606756) were genotyped by iMLDR in 389 CD patients and 746 controls. Furthermore, 102 CD patients and 153 controls were randomly selected for examination of serum homocysteine, folate, and vitamin B 12 levels by enzymatic cycling assay and chemiluminescence immunoassay, respectively. Results: Mutant allele (G) and genotype (AG + GG) of (rs9606756) were higher in CD patients than in controls (both p < 0.05). So were they in ileocolonic CD patients and stricturing CD patients compared to controls (all p < 0.05). Mutant allele (G) and genotype (CG + GG) of (rs1801198) were more prevalent in stricturing CD patients than in controls (both p < 0.05). Compared to controls, average homocysteine level was enhanced in CD patients (p = 0.003), whereas average folate and vitamin B 12 levels were reduced in CD patients (both p < 0.001). The prevalence of hyperhomocysteinemia, folate deficiency, and vitamin B 12 deficiency was higher in CD patients than in controls (all p < 0.01). Both folate deficiency and vitamin B 12 deficiency were independently related to risk of CD (both p < 0.01). Conclusion: TCN2 (rs1801198, rs9606756) polymorphisms as well as folate deficiency and vitamin B 12 deficiency are correlated with CD. [ABSTRACT FROM AUTHOR]

It has been reported that abnormal elevation of homocysteine is quite prevalent in ulcerative colitis (UC) patients. We attempted to explore the relationship of UC with transcobalamin II (TCN2) gene polymorphisms and serum homocysteine, vitamin B, and folate levels in Chinese patients. TCN2 (rs1801198, rs9606756) genotypes were detected by the improved multiple ligase detection reaction (iMLDR) technique in 527 UC patients and 574 controls. Moreover, 128 UC patients and 138 controls were randomly selected for the measurement of homocysteine, vitamin B, and folate levels by enzymatic cycling assay or chemiluminescence immunoassay. For TCN2 (rs1801198), the frequency of allele G and combined frequencies of CG and GG genotypes were increased in patients with mild, moderate, and severe UC compared with those with remission UC (all P < 0.001). The average homocysteine level was elevated (10.78 ± 3.33 vs 9.91 ± 2.88 μmol/L, P = 0.024), whereas the average vitamin B and folate levels were reduced (408.66 ± 185.00 vs 457.42 ± 206.47 pg/mL, P = 0.044; 6.81 ± 3.06 vs 8.17 ± 2.58 ng/mL, P < 0.001, respectively) in UC patients than in controls. Compared with controls, the prevalence of hyperhomocysteinemia (HHcy >15.0 μmol/L), vitamin B deficiency (<203.0 pg/mL), and folate deficiency (<4.0 ng/mL) was higher in UC patients (all P < 0.05). Both HHcy and folate deficiency were shown to be independent risk factors for UC (95% CI = 1.206-12.293, P = 0.023; 95% CI = 1.910-11.129, P = 0.001, respectively). TCN2 (rs1801198, rs9606756) mutations might aggravate the severity of UC. HHcy and folate deficiency are independent risk factors for UC. [ABSTRACT FROM AUTHOR]

Vitamin B12 (cobalamin) deficiency is prevalent worldwide and causes megaloblastic anemia and neurologic deficits. While the anemia can be treated, the neurologic deficits can become refractive to treatment as the disease progresses. Therefore, timely intervention is critical for a favorable outcome. Moreover, the metabolic basis for the neuro-pathologic changes and the role of cobalamin deficiency in the pathology still remains unexplained. Using a transcobalamin receptor / CD320 knockout mouse that lacks the receptor for cellular uptake of transcobalamin bound cobalamin, we aimed to determine whether cobalamin deficiency in the central nervous system produced functional neurologic deficits in the mouse that would parallel those observed in humans. Our behavioral analyses indicate elevated anxiety and deficits in learning, memory and set-shifting of a spatial memory task in the KO mouse. Consistent with the behavioral deficits, the knockout mouse shows impaired expression of the early phase of hippocampal long-term potentiation along with reduced expression of GluR1, decreased brain mass and a significant reduction in the size of nuclei of the hippocampal pyramidal neurons. Our study suggests that the CD320 knockout mouse develops behavioral deficits associated with cobalamin deficiency and therefore could provide a model to understand the metabolic and genetic basis of neuro-pathologic changes due to cobalamin deficiency. [ABSTRACT FROM AUTHOR]

Background: Human placenta expresses CD320, a receptor that ensures the uptake of holo-transcobalamin (holoTC). Soluble CD320 (sCD320) is present in the circulation and its concentration increases during pregnancy.Aims: To investigate a possible association of sCD320, holoTC and total transcobalamin (TC) with the risk of subsequent preeclampsia using serum samples from asymptomatic first trimester pregnant women. Moreover, we aimed to establish reference intervals of the aforementioned biomarkers for first trimester pregnant women who remained healthy throughout pregnancy.Study Design: This study was a retrospective case-control study that we performed on biobank serum samples. Cases (n = 50) and controls (n = 198) (matched for gestational age and date of sample collection) were asymptomatic women in early pregnancy [median (range) gestational age = 10 (8-12) weeks]. Cases developed preeclampsia while the controls remained normotensive throughout pregnancy. We measured the serum concentration of sCD320, holoTC, and total TC by using in-house ELISA methods.Results: First trimester median concentrations of sCD320, holoTC and total TC were not significantly different between cases and controls. The odd ratio for developing preeclampsia based on exposure to low or high levels of sCD320, holoTC or total TC at first trimester was not significant. The reference intervals (2.5-97.5% percentiles (median)) derived from the controls were 50-170 (90) pmol\L for sCD320, 20-140 (70) pmol\L for holoTC and 560-1300 (810) pmol\L for total TC.Conclusions: The risk of preeclampsia is not predicted by first trimester serum concentrations of sCD320, holoTC or total TC. The first trimester reference intervals for the three parameters is reported. [ABSTRACT FROM AUTHOR]

Background: Measurement of holotranscobalamin (holoTC) is increasingly used as a screening test for cobalamin (Cbl) deficiency. A level well below the reference interval strongly supports a deficient state. We examined a 21-year-old woman diagnosed as Cbl deficient because of an extremely low holoTC level as measured by the Abbott Architect Assay. Methods: The patient was evaluated for Cbl deficiency employing an in-house holoTC method as well as other routine markers of Cbl status. Further analyses included exploration of the Cbl binding proteins employing gel filtration of a serum sample saturated with 57 Co-labeled Cbl and Sanger sequencing of exons 1-9 and the intron-exon boundaries of the TCN2 gene, the gene coding for transcobalamin (TC). Results: The patient had normal hematological variables throughout. Despite initial treatment with Cbl, holoTC as measured by the Abbott assay remained low, while holoTC measured with the in-house assay was normal, and behaved as TC upon gel-filtration. By Sanger sequencing, we detected a homozygous single point mutation c.855T > A in exon 6 of TCN2, corresponding to a asparagine (Asn) to lysine (Lys) substitution in position 267 of the mature protein. Conclusions: We describe a novel point mutation of the TCN2 gene. The mutation does not seem to interfere with the function of TC, but the mutation may well explain the low level of holoTC detected by the Abbott assay. Our results underscores that mutations of TCN2 have to be considered when implausible holoTC results are obtained. [ABSTRACT FROM AUTHOR]