Sign Up for a Free Account

This is an image preview.
Start a Free Account
to view the full image.

Sign Up for a Free Account For information on discounts, see Plans & Pricing

  • Nearly 3,000 illustrations, including video clips of neurologic disorders.

  • Every article is reviewed by our esteemed Editorial Board for accuracy and currency.

  • Full spectrum of neurology in 1,200 comprehensive articles.

  • Listen to MedLink on the go with Audio versions of each article.

Ammonia is detoxified through its conversion to urea by the enzymes in the small boxes

Ammonia is detoxified through its conversion to urea by the enzymes in the small boxes, whose abbreviations are spelled out below. NAGS catalyzes the synthesis of N-acetylglutamate from acetyl-CoA and glutamate. Deficiency of NAGS (highlighted in red) causes hyperammonemia along with accumulation of plasma glutamine and decreased to normal plasma citrulline and arginine concentrations. Urinary orotic acid is decreased or normal. NAGS, N-acetylglutamate synthase; CPS1, carbamoylphosphate synthetase 1; OTC, ornithine transcarbamylase; ASS, argininosuccinate synthetase; ASL, argininosuccinate lyase; ARG1, arginase 1. (Adapted from Zschocke and Hoffmann 2011.)

Associated Disorders

  • Ataxia
  • Carbonic anhydrase VA deficiency
  • Cerebral palsy
  • Congenital hyperammonemia
  • Hyperinsulinism-hyperammonemia syndrome
  • Hyperornithinemia - hyperammonemia - homocitrullinuria syndrome
  • Intellectual disability
  • Lysinuric protein intolerance
  • Maple syrup urine disease
  • Ornithine transcarbamylase deficiency
  • Reye syndrome
  • Urea cycle disorders (others)
  • Valproate sensitivity