The main goals in the treatment of arginase deficiency are to lower arginine levels and to prevent buildup of ammonia in the blood (hyperammonemia). People with arginase deficiency must be closely supervised by a medical team with experience treating metabolic disorders. They may need frequent blood tests to check arginine levels.
Because arginine is a building block of protein, people with arginase deficiency must follow a diet that is very low in protein. It is often recommended they eat the minimal amount of protein needed to maintain good health, which varies based on many factors including age and weight. Protein is found in high amounts in meat, fish, beans, dairy products, eggs and nuts. However, it also occurs in foods like pasta, fruit and vegetables. Under the guidance of a metabolic dietitian, people with arginase deficiency must closely monitor all the protein they eat. They are often advised to drink special formulas and/or buy medical foods in which the protein levels are tailored to fit their needs. People with arginase deficiency may also need to take certain medications (called nitrogen-scavenging drugs) to reduce their levels of arginine.
If people with arginase deficiency have episodes of hyperammonemia, they may be given intravenous (IV) fluids. During an episode of severe hyperammonemia, people with arginase deficiency are generally treated in the hospital. They may require dialysis, nitrogen-scavenging medications, intravenous (IV) fluids, or other treatments. These treatments are given to quickly reduce blood ammonia levels and prevent brain damage.
Last updated: 4/25/2017
What is the long-term outlook for people with arginase deficiency?
The long-term outlook (prognosis) for people with arginase deficiency varies from person to person. It depends on many factors, including the severity of the disorder, the person's ability to follow the strict diet recommendations, and the response to treatment. For example, some children appear to have more severe intellectual disability while others are more physically affected (e.g. severe spasticity with joint contractures). It is thought that approximately 75% of people with arginase deficiency live long lives.
If the disorder is not diagnosed or if a person with arginase deficiency is unable to follow the strict diet, the prognosis is poor and may include severe intellectual disability and muscle stiffness, loss of the ability to walk, and loss of bladder and bowel control. However, even with treatment, the outcome can vary. In some cases, treatment has been shown to significantly lower arginine levels in both the blood and the cerebrospinal fluid, with some people even having near normal levels. With this response, continued treatment would be expected to improve long-term outlook and prevent progression of neurological symptoms. However, some people with arginase deficiency who follow the recommended treatment regimen may continue to have high levels of arginine in their blood, which can be associated with symptoms that worsen over time. In fact, one older study found that 50% of people with arginase deficiency who are compliant with treatment see an improvement in symptoms, 25% have symptoms that remain the same, and 25% experience a progression of the metabolic disorder.
Nonetheless, early diagnosis in the clinical course allows for improved outcome in most cases. Following a low-protein diet is essential for a better prognosis. Patients and caregivers need to be instructed to seek early medical attention for illnesses, such as fever, because hyperammonemia, although uncommon in this disease, can occur.
Last updated: 4/25/2017
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
Schlune A, Vom Dahl S, Häussinger D, Ensenauer R, Mayatepek E. Hyperargininemia due to arginase I deficiency: the original patients and their natural history, and a review of the literature. Amino Acids. September 2015; 47(9):1751-1762. https://www.ncbi.nlm.nih.gov/pubmed/?term=26123990.
Prasad AN, Breen JC, Ampola MG, Rosman NP. Argininemia: a treatable genetic cause of progressive spastic diplegia simulating cerebral palsy: case reports and literature review. J Child Neurol. August 1997; 12(5):301-309. https://www.ncbi.nlm.nih.gov/pubmed/?term=9378897.