Argininosuccinic Aciduria (ASL)
Argininosuccinic aciduria is a pan-ethnic autosomal recessive disease caused by pathogenic variants in the gene ASL. It prevents the body from properly removing ammonia from the blood, causing periods of hyperammonemia (high levels of ammonia in the blood). The clinical presentation is variable, and there are two main forms: Neonatal onset: Within the first days of life, babies with neonatal onset argininosuccinic aciduria experience vomiting, lethargy, and hypothermia. Affected individuals will be at risk for hyperammonemic episodes throughout life. Late onset: Hyperammonemic episodes begin later in life and are usually triggered by stress or illness. Either type of the disease can result in attention deficit hyperactivity disorder, developmental delay, seizures, liver disease, brittle hair, and hypertension. As a metabolic disease, argininosuccinic aciduria is usually treated with a special diet in addition to medication. When it is controlled with diet and medication, life expectancy is normal. It is not possible to predict the severity of disease based on the variants inherited.
For information about carrier frequency and residual risk, please see the residual risk table.