The clinical presentation of cobalamin-related disorders: From acquired deficiencies to inborn errors of absorption and intracellular pathways.
Level 5 - mechanism / opinion, no new human data
Narrative review without systematic search or meta-analytic pooling
PubMed 30761552 · doi:10.1002/jimd.12012
What was done
This narrative review synthesizes the clinical presentation, management, and outcomes of nutritional and acquired vitamin B12 deficiencies, inborn errors of cobalamin absorption and intracellular trafficking, and remethylation pathway defects (MTHFD1 and MTHFR deficiencies).
What was found
The abstract reports no numerical data or quantitative outcomes. It describes characteristic multisystem features of cobalamin-related disorders, including failure to thrive, neurocognitive and psychiatric symptoms, ocular disease, bone marrow abnormalities, microangiopathy, and thromboembolic events, with severe immune deficiency specifically identified in MTHFD1 defects. Mechanistic impacts include impaired methylation capacity, metabolite accumulation, oxidative stress, and altered immune and cytokine regulation.
Why it matters
The paper provides a comprehensive clinical and biochemical categorization of both acquired and genetic defects along the cobalamin and remethylation pathways.
Limits
As a narrative review, the paper does not use systematic search or selection methods. The abstract provides no primary data, sample sizes, effect estimates, or comparative treatment outcome metrics.
Cited by
- contradicts Cyanocobalamin does not break down or become active in individuals with methylation issues, resulting in toxic buildup in the body.