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Hereditary orotic aciduria

Disease definition

A rare genetic disorder of pyrimidine metabolism characterized by early onset of megaloblastic anemia, global developmental delay, and failure to thrive, associated with massive urinary overexcretion of orotic acid (sometimes with orotic acid crystalluria). Patients without megaloblastic anemia, but with additional manifestations such as epilepsy, have also been reported.


Classification level: Disorder
  • Synonym(s):
    • Orotidylic decarboxylase deficiency
    • Uridine monophosphate synthetase deficiency
  • Prevalence: <1 / 1 000 000
  • Inheritance: Autosomal recessive 
  • Age of onset: Infancy, Neonatal
  • ICD-10: E79.8
  • ICD-11: 3A03.0
  • OMIM: 258900
  • UMLS: C0220987
  • MeSH: C537136
  • GARD: 5429
  • MedDRA: 10052621
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