Argininosuccinic Aciduria




Argininosuccinic aciduria is an inherited disorder that causes ammonia to accumulate in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia.

Argininosuccinic aciduria usually becomes evident in the first few days of life. An infant withargininosuccinic aciduria may be lacking in energy (lethargic) or unwilling to eat, and have poorly controlled breathing rate or body temperature. Some babies with this disorder experience seizures or unusual body movements, or go into a coma. Complications from argininosuccinic aciduria may include developmental delay and intellectual disability. Progressive liver damage, skin lesions, and brittle hair may also be seen.

Occasionally, an individual may inherit a mild form of the disorder in which ammonia accumulates in the bloodstream only during periods of illness or other stress.



  • Aminoaciduria
  • Elevated blood ammonia level
  • Vomiting
  • Seizures
  • Abnormal hair shaft
  • Refusal to eat
  • Aminoaciduria
  • Hyperglutaminemia
  • Hypoargininemia
  • Oroticaciduria


The condition is caused by mutations in the ASL gene and is inherited in anautosomal recessive pattern. Long-term management includes dietary restriction of protein and supplementation with arginine. Acute crises may be treated by discontinuing oral protein intake, supplementing oral intake with intravenous lipids and/or glucose, and use of intravenous arginine and nitrogen scavenging therapy. If ammonia levels do not normalize, hemodialysis may be necessary.


  • NIH
  • Genetics Home Reference