Argininosuccinic Aciduria (ASA)



Argininosuccinic aciduria (ASA) is a condition that causes dangerous amounts of ammonia to build up in the body. Individuals with ASA are unable to process the waste product ammonia, which is produced when the body breaks down amino acids. ASA is also described as a urea cycle condition. This name is used to describe conditions in which the body’s system for removing ammonia from the blood is not working correctly. Early detection and treatment can prevent many of the serious outcomes of ASA. There are two main forms of ASA, each differing in the age of onset. The first and most common form is seen in babies, usually in the first few days after birth. The second form is less common and is seen in children. Sometimes signs of ASA are not apparent until late infancy or early childhood. In these cases, the signs are usually less severe. Signs of ASA in babies include poor appetite, sleeping longer or more often, tiredness, irritability, vomiting, trouble breathing, seizures (epilepsy), involuntary or uncontrolled body movements, and delayed growth. Many of these signs may occur when a baby eats foods the body cannot break down. Symptoms can be triggered by long periods of time without eating, illnesses, and infections.

Condition Type:

Core Conditions


Argininosuccinic aciduria (ASA) affects 1 out of every 70,000 babies born in the United States.

More Information for Parents:
Also known as:
  • ASA
  • Argininosuccinate lyase deficiency
  • Argininosuccinic acid lyase deficiency
  • Argininosuccinic acidemia
  • ASL deficiency
  • Arginine succinyl-CoA lyase deficiency

Core Conditions