EARLY SIGNS
There are two main forms of arginosuccinic aciduria (ASA), which differ in the age of onset. The first and most common form is seen in newborns. The first signs of ASA usually begin in the first few days after birth.
The second form is less common and is seen in children. Sometimes signs of ASA might not become 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 (also called epilepsy)
- Involuntary or uncontrolled body movements
- Delayed growth
Many of these signs may occur when your baby eats foods that his or her body cannot break down. They can be triggered by long periods of time without eating, illnesses, and infections.
CAUSES
When we eat food, enzymes help break it down. Some enzymes break down proteins into their building blocks, called amino acids. Other enzymes break down these amino acids. When we break down proteins, our bodies need even more enzymes to get rid of waste products. In arginosuccinic aciduria, the enzyme arginosuccinic acid lyase (ASAL) is not working correctly.
ASAL’s job is to help get rid of ammonia by breaking it down into urine. Ammonia is a waste product of protein breakdown.?
Babies with argininosuccinic aciduria (ASA) either do not make enough or make non-working ASAL. When ASAL does not work correctly, the body cannot remove ammonia through the urine. This causes a dangerous build-up of ammonia in the body.
ASA is an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for ASA, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with ASA is rare, when both parents are carriers, they can have more than one child with the condition.
TREATMENT
Dietary Treatment
Your baby may need to follow a low-protein diet to avoid certain foods that he or she cannot break down. A dietician or nutritionist can help you plan the appropriate diet for your child’s healthy growth.
Your baby’s doctor might also recommend special formulas and foods for children with arginosuccinic aciduria (ASA). These formulas will likely need to continue through adulthood.
Supplements and Medications
Many babies with ASA take arginine supplements. Arginine is a natural substance, and it can help lower the high ammonia levels that result from ASA. Everyone has some ammonia in his or her blood, but high levels can be toxic. Your baby’s doctor can write you a prescription for these supplements.
EXPECTED OUTCOMES
When arginosuccinic aciduria (ASA) is treated early, children can have healthy growth and development. This is why screening for ASA is so important. Newborn screening can allow for treatment before ammonia levels become dangerously high in your baby’s bloodstream.
Some children still have high ammonia levels in their blood even with treatment. These children may need to seek treatment in a hospital to remove the ammonia from their blood.
It is very important to treat ASA. Babies who do not receive treatment are at risk for intellectual disabilities, developmental delays, liver damage, brain damage, coma, or death.