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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.)

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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