- Human pathology

Home > D. General pathology > Genetic and developmental anomalies > Genetic metabolic diseases > urea cycle diseases

urea cycle diseases

Monday 19 April 2004

Urea-cycle disorders (UCDs) are a group of inborn errors of hepatocyte metabolism that are caused by the loss of enzymes involved in the process of transferring nitrogen from ammonia to urea, via the urea cycle (UC).

Urea cycle disorders are characterized by the triad of hyperammonemia, encephalopathy, and respiratory alkalosis.

Five disorders involving different defects in the biosynthesis of the enzymes of the urea cycle have been described: OTC deficiency, carbamyl phosphate synthetase deficiency (MIM.237300), argininosuccinate synthetase deficiency or citrullinemia (MIM.215700), argininosuccinate lyase deficiency (MIM.207900), and arginase deficiency (MIM.207800).


- ornithine transcarbamylase deficiency (MIM.311250 Xp21.1)
- carbamyl phosphate synthetase deficiency (MIM.237300 2q35 )
- citrullinemia (MIM.215700 9q34.1)
- argininosuccinic aciduria (MIM.207900)
- argininemia (MIM.207800)
- hyperornithinemia, hyperammonemia, homocitrullinuria syndrome (HHH syndrome) (MIM.238970)


- urea cycle


- Mian A, Lee B. Urea-cycle disorders as a paradigm for inborn errors of hepatocyte metabolism. Trends Mol Med. 2002 Dec;8(12):583-9. PMID: 12470992