Hereditary orotic aciduria

What is Hereditary orotic aciduria?

A rare autosomal recessive disorder characterized by retarded growth, anemia and excessive urinary excretion of orotic acid. It is due to a severe deficiency in the activity of the pyrimidine pathway enzyme uridine 5'-monophosphate (UMP) synthase (bifunctional enzyme containing two activities: orotate phosphoribosyltransferase and orotidine 5'-monophosphate decarboxylase), coded by a single gene (UMPS) localized to chromosome 3q13.

Other condition names

  • Orotidylic decarboxylase deficiency
  • Uridine monophosphate synthetase deficiency

Inheritance type

Autosomal recessive


  • Worldwide: <1 in 1,000 000

Age of Onset

  • Infancy
  • Neonatal
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