Recurrent Encephalopathy: NAGS (N-acetylglutamate Synthase) Deficiency in Adults

Can J Neurol Sci. 2013 Jan;40(1):3-9. doi: 10.1017/s0317167100012877.


N-acetyl-glutamate synthase (NAGS) deficiency is a rare autosomal recessive urea cycle disorder (UCD) that uncommonly presents in adulthood. Adult presentations of UCDs include; confusional episodes, neuropsychiatric symptoms and encephalopathy. To date, there have been no detailed neurological descriptions of an adult onset presentation of NAGS deficiency. In this review we examine the clinical presentation and management of UCDs with an emphasis on NAGS deficiency. An illustrative case is provided. Plasma ammonia levels should be measured in all adult patients with unexplained encephalopathy, as treatment can be potentially life-saving. Availability of N-carbamylglutamate (NCG; carglumic acid) has made protein restriction largely unnecessary in treatment regimens currently employed. Genetic counselling remains an essential component of management of NAGS.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Adult
  • Amino-Acid N-Acetyltransferase
  • Ammonia / blood
  • Brain Diseases / etiology*
  • Brain Diseases / mortality
  • Brain Diseases / therapy
  • Female
  • Humans
  • Male
  • Metabolic Networks and Pathways / physiology
  • Urea Cycle Disorders, Inborn / complications*
  • Urea Cycle Disorders, Inborn / mortality
  • Urea Cycle Disorders, Inborn / therapy


  • Ammonia
  • Amino-Acid N-Acetyltransferase

Supplementary concepts

  • N-acetyl glutamate synthetase deficiency