Argininosuccinic Aciduria (ASA)

Argininosuccinic Acidemia (ASA)
A Urea Cycle Disorder

Argininosuccinic Acidemia is also known as Argininosuccinic Aciduria, Argininosuccinase Deficiency, and Argininocuccinate Lyase Deficiency (ALD).

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What is it?
Argininosuccinic Acidemia (ASA) is a disorder of the urea cycle. Patients with urea cycle disorders cannot convert nitrogen in the form of ammonia into urea. Build-up of ammonia is toxic and can cause brain damage. Nitrogen in ammonia comes from protein in the food we eat or the breakdown of protein from the muscle when we are sick. Without the urea cycle, ammonia will build up to dangerous levels when we take in too much protein or when we are sick. ASA is one of the urea cycle disorders and is caused by deficiency of an enzyme called argininosuccinic acid lyase in the body. This prevents the conversion of argininosuccinic acid (ASA) into arginine. The build-up in ASA if too high ultimately causes a build-up in ammonia. At the same time, arginine may be deficient.

Inheritance and Frequency
The gene defect for ASA is an autosomal recessive genetic trait and is unknowingly passed down from generation to generation. This faulty gene usually emerges when two carriers have children together and pass it to their offspring. For each pregnancy of two such carriers, there is a 25% chance that the child will be born with the disease and a 50% chance the child will be a carrier for the gene defect.

Studies show that 1 of every 70,000 live births will have some form of ASA.

Signs & Symptoms
Symptoms are hyperammonemia accompanied by lack of appetite, vomiting, listlessness, seizures, and coma. Onset is usually at birth, but symptoms may not be noticeable for days or weeks.

Long Term Effects
When left untreated, brain damage, coma, and death will occur.

Treatment
Treatment may include a high-caloric, protein-restrictive diet, arginine supplementation, administration of sodium benzoate and sodium phenylacetate. In some affected individuals dialysis may be necessary.

History
It is reported that fewer than 100 people in the U.S. are affected with Argininosuccinic Acidemia.

Screening
Visit the What Does Your State Screen page to learn about your state's newborn screening program.

Supplemental Screening
If you live in a state that does not perform screening on its newborns for all detectable disorders, there are laboratories that will provide this screening for you no matter your state of residence. For more information about supplemental screening, visit our supplemental screening page. Also visit our frequently asked questions page for more information on newborn screening.

Other Sites of Reference

Support Groups

ASA Kids - Argininosuccinic Aciduria
Phone: (409) 735-4332
Contact Person: write to Jamie Oliphint

National Urea Cycle Disorders Foundation
4841 Hill Street
La Canada, CA 91011
Phone: 1-800-38NUCDF
Contact Person: write to Cynthia LeMons

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Revised 11/22/2006