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What is Argininemia?

Argininemia belongs to a group of disorders called urea cycle disorders. Individuals with argininemia are missing an important enzyme called arginase. Lack of this enzyme leads to high levels of arginine in the blood.

Most affected individuals present with symptoms between the ages of 1 and 3 years, although cases of earlier onset have been reported. Symptoms typically include poor growth, stiff muscles (spasticity), seizures, and intellectual disability including loss of skills. Some individuals may also have microcephaly (small head size), liver cirrhosis, problems with balance and coordination, or episodes of hyperammonemia (high levels of ammonia in the blood). Hyperammonemia may cause additional complications like lethargy or vomiting.

How common is Argininemia?

Argininemia is a rare condition that occurs in about 1 in 350,000 to 1 in 1,000,000 births.

How is Argininemia treated?

People affected with argininemia will be monitored by a metabolic specialist. Appropriate treatment can lower the risk of hyperammonemic crises and may even reverse some of the neurological symptoms associated with argininemia. Treatment includes adherence to a protein-restricted diet, supplementation of necessary amino acids, and the use of medications to lower the levels of arginine in the blood. Seizures can be treated with medication, but valproic acid should be avoided. Liver transplantation may be considered if hyperammonemia cannot be otherwise controlled. During a severe hyperammonemic crisis, treatment is given to quickly reduce ammonia levels in the blood to prevent brain damage. Such treatment will likely take place in the hospital.

What is the prognosis for a person with Argininemia?

Without treatment, individuals will experience poor growth, stiff muscles, developmental delay, and intellectual disability. Lifespan is expected to be normal in most affected individuals, but some may die early from complications of a hyperammonemic crisis. With treatment, some neurological symptoms may be reversed and the risk of hyperammonemic crises may be reduced over the course of the individual's life, thereby improving outcomes.