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Simplified scheme of the two metabolic pathways that use cobalamin cofactors

Legend: AdoCbl, adenosylcobalamin; Cys, cystine; Cyst, cystathionine; Hcy, homocysteine; MeCbl, methyladenosylcobalamin; Met cycle, methionine cycle; MCM, methylmalonyl-CoA mutase; MMA, methylmalonic acid; MS, methionine synthase; MTHF, N5-methyltetrahydrofolate; SAH, S-adenosylhomocysteine; SAM, S-adenosylmethionine; TCA cycle, tricarboxylic acid cycle; THF, tetrahydrofolate. (Source: Lipari Pinto P, Florindo C, Janeiro P, et al. Acquired vitamin B12 deficiency in newborns: positive impact on newborn health through early detection. Nutrients 2022;14[20]:4397. Creative Commons Attribution 4.0 International [CC BY 4.0] license,

Associated Disorders

  • Alcohol-tobacco amblyopia
  • Cerebral vascular disease
  • Dementia
  • Depression
  • Developmental delay
  • Folate deficiency
  • Gastric resection
  • Glossitis
  • Imerslund-Grasbeck syndrome
  • Malabsorption
  • Megaloblastic anemia
  • Myelopathy
  • Optic neuropathy
  • Pernicious anemia
  • Polyneuropathy
  • Regional enteritis
  • Subacute combined degeneration of the spinal cord