Orphanet: Homocystinuria without methylmalonic aciduria

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Homocystinuria without methylmalonic aciduria

Disease definition

Homocystinuria without methylmalonic aciduria is an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, encephalopathy and, sometimes, developmental delay, and associated with homocystinuria and hyperhomocysteinemia. There are three types of homocystinuria without methylmalonic aciduria; cblE, cblG and cblD-variant 1 (cblDv1).


Classification level: Disorder
  • Synonym(s):
    • Functional methionine synthase deficiency
    • Methylcobalamin deficiency
  • Prevalence: <1 / 1 000 000
  • Inheritance: Autosomal recessive 
  • Age of onset: All ages
  • ICD-10: E72.1
  • OMIM: 236270  250940  277410
  • UMLS: -
  • MeSH: -
  • GARD: -
  • MedDRA: -

Detailed information


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