Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Argininosuccinic aciduria

Reviewed March 2007

What is 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 with argininosuccinic 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.

How common is argininosuccinic aciduria?

Argininosuccinic aciduria occurs in approximately 1 in 70,000 newborns.

What genes are related to argininosuccinic aciduria?

Mutations in the ASL gene cause argininosuccinic aciduria.

Argininosuccinic aciduria belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of reactions that occur in liver cells. It processes excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys.

In argininosuccinic aciduria, the enzyme that starts a specific reaction within the urea cycle is damaged or missing. The urea cycle cannot proceed normally, and nitrogen accumulates in the bloodstream in the form of ammonia.

Ammonia is especially damaging to the nervous system, so argininosuccinic aciduria causes neurological problems as well as eventual damage to the liver.

Related Gene(s)

Changes in this gene are associated with argininosuccinic aciduria.

  • ASL

How do people inherit argininosuccinic aciduria?

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Where can I find information about diagnosis or management of argininosuccinic aciduria?

These resources address the diagnosis or management of argininosuccinic aciduria and may include treatment providers.

  • Baby's First Test (
  • Gene Review: Argininosuccinate Lyase Deficiency (
  • Gene Review: Urea Cycle Disorders Overview (
  • Genetic Testing Registry: Argininosuccinate lyase deficiency (
  • MedlinePlus Encyclopedia: Hereditary urea cycle abnormality (

You might also find information on the diagnosis or management of argininosuccinic aciduria in Educational resources and Patient support.

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook. Read more about genetic testing (, particularly the difference between clinical tests and research tests (

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about argininosuccinic aciduria?

You may find the following resources about argininosuccinic aciduria helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for argininosuccinic aciduria?

  • Argininosuccinate lyase deficiency
  • argininosuccinic acidemia
  • Argininosuccinicaciduria
  • argininosuccinyl-CoA lyase deficiency
  • arginosuccinase deficiency
  • ASA
  • ASAuria
  • ASL deficiency

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about argininosuccinic aciduria?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding argininosuccinic aciduria?

aciduria ; ammonia ; autosomal ; autosomal recessive ; cell ; class ; CoA ; coma ; compound ; deficiency ; developmental delay ; disability ; enzyme ; gene ; inherit ; inherited ; lacking in energy ; lethargic ; nervous system ; neurological ; newborn screening ; protein ; recessive ; screening ; stress ; toxic ; urea

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Gene Review: Urea Cycle Disorders Overview (
  • Kleijer WJ, Garritsen VH, Linnebank M, Mooyer P, Huijmans JG, Mustonen A, Simola KO, Arslan-Kirchner M, Battini R, Briones P, Cardo E, Mandel H, Tschiedel E, Wanders RJ, Koch HG. Clinical, enzymatic, and molecular genetic characterization of a biochemical variant type of argininosuccinic aciduria: prenatal and postnatal diagnosis in five unrelated families. J Inherit Metab Dis. 2002 Sep;25(5):399-410. (
  • Lee B, Goss J. Long-term correction of urea cycle disorders. J Pediatr. 2001 Jan;138(1 Suppl):S62-71. Review. (
  • National Organization for Rare Disorders (NORD) (
  • National Urea Cycle Disorders Foundation (
  • Reid Sutton V, Pan Y, Davis EC, Craigen WJ. A mouse model of argininosuccinic aciduria: biochemical characterization. Mol Genet Metab. 2003 Jan;78(1):11-6. (
  • Scaglia F, Brunetti-Pierri N, Kleppe S, Marini J, Carter S, Garlick P, Jahoor F, O'Brien W, Lee B. Clinical consequences of urea cycle enzyme deficiencies and potential links to arginine and nitric oxide metabolism. J Nutr. 2004 Oct;134(10 Suppl):2775S-2782S; discussion 2796S-2797S. Review. (
  • Stadler S, Gempel K, Bieger I, Pontz BF, Gerbitz KD, Bauer MF, Hofmann S. Detection of neonatal argininosuccinate lyase deficiency by serum tandem mass spectrometry. J Inherit Metab Dis. 2001 Jun;24(3):370-8. (
  • Urea Cycle Disorders Consortium (
  • Wilcken B, Smith A, Brown DA. Urine screening for aminoacidopathies: is it beneficial? Results of a long-term follow-up of cases detected bny screening one millon babies. J Pediatr. 1980 Sep;97(3):492-7. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: March 2007
Published: February 8, 2016