The Many Faces of Cobalamin (Vitamin B12) Deficiency

Although cobalamin (vitamin B12) deficiency was described over a century ago, it is still difficult to establish the correct diagnosis and prescribe the right treatment. Symptoms related to vitamin B12 deficiency may be diverse and vary from neurologic to psychiatric. A number of individuals with vitamin B12 deficiency may present with the classic megaloblastic anemia. In clinical practice, many cases of vitamin B12 deficiency are overlooked or sometimes even misdiagnosed. In this review, we describe the heterogeneous disease spectrum of patients with vitamin B12 deficiency in whom the diagnosis was either based on low serum B12 levels, elevated biomarkers like methylmalonic acid and/or homocysteine, or the improvement of clinical symptoms after the institution of parenteral vitamin B12 therapy. We discuss the possible clinical signs and symptoms of patients with B12 deficiency and the various pitfalls of diagnosis and treatment.</p

A non-invasive risk score including skin autofluorescence predicts diabetes risk in the general population

Abstract Increased skin autofluorescence (SAF) predicts the development of diabetes-related complications and cardiovascular disease. We assessed the performance of a simple model which includes SAF to identify individuals at high risk for undiagnosed and incident type 2 diabetes, in 58,377 participants in the Lifelines Cohort Study without known diabetes. Newly-diagnosed diabetes was defined as fasting blood glucose ≥ 7.0 mmol/l and/or HbA1c ≥ 6.5% (≥ 48 mmol/mol) or self-reported diabetes at follow-up. We constructed predictive models based on age, body mass index (BMI), SAF, and parental history of diabetes, and compared to results with the concise FINDRISC model. At 2nd visit to Lifelines, 1113 (1.9%) participants were identified with undiagnosed diabetes and 1033 (1.8%) participants developed diabetes during follow-up. A model comprising age, BMI and SAF yielded an AUC of 0.783 and was non-inferior to the concise FINDRISC model, which had an AUC of 0.797 to predict new diabetes. At a score of 5.8, sensitivity was 78% and specificity of 66%. Model 2 which also incorporated parental diabetes history, had an AUC of 0.792, and a sensitivity of 74% and specificity of 70% at a score of 6.5. Net reclassification index (NRI) did not improve significantly (NRI 1.43% (− 0.50–3.37 p = 0.15). The combination of an easy to perform SAF measurement with age and BMI is a good alternative screening tool suitable for medical and non-medical settings. Parental history of diabetes did not significantly improve model performance in this homogeneous cohort

Association of vitamin B12, methylmalonic acid, and functional parameters

Introduction: Diagnosis of vitamin B12 deficiency is difficult, as there is no conclusive single test for this disorder. We evaluated the association of serum B12 and methylmalonic acid (MMA) with haematologic parameters and physical and cognitive functioning in an effort to use such clinical parameters to improve the interpretation of serum values. Methods: We used data of participants > 19 years of age from NHANES 2011-2012 and 2013-2014, a cross-sectional survey in the United States. Functional status was assessed with questionnaires on current health condition, disability, hospital utilisation, cognitive functioning, mental health and depression, and physical functioning. Muscle strength assessed with a handgrip dynamometer was used as a performance parameter. Results were evaluated both for the entire population and participants of Western European descent. Because renal function influences MMA concentrations and is a proxy for both frailty and comorbidity, all results were additionally stratified for individuals with normal vs impaired renal function (eGFR < 60 ml/min). Results: In total, data of 9645 participants (mean age 49 (SD 17) years, 49.3% males) were included. Out of all participants with serum B12 < 140, 140-300, and 301-1000 pmol/l, 56.2%, 13.5%, and 4.1%, respectively had elevated MMA. MMA concentrations were more strongly associated with poor functional status and physical performance than serum B12. We identified a significant and independent association of MMA concentrations, as well as haemoglobin and co-morbidity with muscle strength. Conclusions/interpretations: A large proportion of individuals with a decreased serum B12 concentration still has normal MMA concentrations. Elevated MMA concentrations were more strongly associated with poor functional performance than serum B12

Genome-wide association study identifies novel loci associated with skin autofluorescence in individuals without diabetes

BACKGROUND: Skin autofluorescence (SAF) is a non-invasive measure reflecting accumulation of advanced glycation endproducts (AGEs) in the skin. Higher SAF levels are associated with an increased risk of developing type 2 diabetes and cardiovascular disease. An earlier genome-wide association study (GWAS) revealed a strong association between NAT2 variants and SAF. The aim of this study was to calculate SAF heritability and to identify additional genetic variants associated with SAF through genome-wide association studies (GWAS). RESULTS: In 27,534 participants without diabetes the heritability estimate of lnSAF was 33% ± 2.0% (SE) in a model adjusted for covariates. In meta-GWAS for lnSAF five SNPs, on chromosomes 8, 11, 15 and 16 were associated with lnSAF (P  T), which results in a Met30Val missense variant in MMP27 exon 1 (NM_022122.3); 2. rs2470893 (Chr15:75,019,449,C > T), in intergenic region between CYP1A1 and CYP1A2; with attenuation of the SNP-effect when coffee consumption was included as a covariate; 3. rs12931267 (Chr16:89,818,732,C > G) in intron 30 of FANCA and near MC1R; and following conditional analysis 4. rs3764257 (Chr16:89,800,887,C > G) an intronic variant in ZNF276, 17.8 kb upstream from rs12931267; finally, 30 kb downstream from NAT2 5. rs576201050 (Chr8:18,288,053,G > A). CONCLUSIONS: This large meta-GWAS revealed five SNPs at four loci associated with SAF in the non-diabetes population. Further unravelling of the genetic architecture of SAF will help in improving its utility as a tool for screening and early detection of diseases and disease complications. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12864-022-09062-x