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Metabolic pathways involved in remethylation disorders

Legend: AdoCbl, adenosyl-Cbl; AdoHcy, adenosylhomocysteine; AdoMet, adenosylmethionine; BHMT, betaine homocysteine methyltransferase; cbl C-G, cobalamin C-G; CBS, cystathionine-beta-synthase; CH2-THF, 5,10-methylenetetrahydrofolate; CH3-THF or MTHF, methyl-tetrahydrofolate; CoIIbl and CoIIIbl indicate different redox states of cobalamin, with Co2+ and Co3+, respectively; DHF, dihydrohydrofolate; DMG, dimethylglycine; Gly, glycine; HC or Hcy, homocysteine; MeCbl, methylcobalamin; Met, methionine; MS, methionine synthase; MSR, methionine synthase reductase; MTHFR, methylenetetrahydrofolate reductase; OHCbl, hydroxotranscobalamin; Ser, serine; TC, transcobalamin; THF, tetrahydrofolate. Note: Minor inconsistencies in the original labeling have been clarified in the revised legend by Dr. Douglas J Lanska. (Source: Huemer M, Diodato D, Schwahn B, et al. Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency. J Inherit Metab Dis 2017;40[1]:21-48. Creative Commons Attribution 4.0 International 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