Argininosuccinic aciduria

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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.

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.

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.

MedlinePlus - Health information (4 links)
Educational resources - Information pages (7 links)
Patient support - For patients and families (4 links)

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

Gene Reviews - Clinical summary (2 links)
Genetic Testing Registry - Repository of genetic test information (1 link)
ACT Sheets - Newborn screening follow up (1 link)
ClinicalTrials.gov - Linking patients to medical research
PubMed - Recent literature
OMIM - Genetic disorder catalog

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

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding argininosuccinic aciduria?

aciduria ; ammonia ; autosomal ; autosomal recessive ; cell ; class ; CoA ; coma ; compound ; deficiency ;developmental delay ; disability ; enzyme ; gene ; 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.

References (11 links)

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.