What is Argininemia?

Argininemia is a urea cycle disorder caused by harmful genetic changes (mutations) in the ARG1 gene. Individuals with argininemia have arginase deficiency, which leads to toxic levels of arginine and ammonia in the body. Symptoms typically include poor growth, stiff muscles (spasticity), seizures, loss of skills (developmental regression), and intellectual disability. Some individuals may also have a small head size (microcephaly), scarring of the liver (cirrhosis), problems with balance and coordination, or episodes of high levels of ammonia (hyperammonemia) in the blood. Hyperammonemia may cause additional complications like lack of energy (lethargy) or vomiting. Most affected individuals present with symptoms between the ages of one and three years, although cases of earlier onset have been reported.

How common is Argininemia?

The incidence of argininemia in the population is 1 in 350,000 to 1 in 1,000,000 births.

How is Argininemia treated?

There is no cure for argininemia. Treatment for argininemia is dietary, through restriction of dietary protein and by taking necessary amino acids. Additionally, medications called nitrogen-scavenging drugs may help maintain lower amounts of ammonia in the body. Seizures can be treated with medication, but valproic acid should be avoided. In individuals where ammonia levels cannot be managed, a liver transplant may be considered. Acute episodes of hyperammonemia (hyperammonemic crisis) are treated in a hospital to quickly reduce ammonia levels in the blood, to prevent brain damage. All individuals with argininemia will be followed by a metabolic specialist.

What is the prognosis for an individual with Argininemia?

Without treatment, individuals will experience poor growth, stiff muscles, developmental delay, and intellectual disability. Lifespan is normal in most affected individuals, but some may die early from complications of extremely high ammonia (hyperammonemic crisis). With treatment, some neurological symptoms may be stabilized and the risk of hyperammonemic crises may be reduced over the course of the individual's life.

Other names for

  • ARG1 deficiency
  • Arginase deficiency
  • Hyperargininemia


  • Carvalho et al., 2012, Gene, 509(1):124-30, PMID: 22959135
  • Crombez et al., 2005, Mol Genet Metab, 84(3):243-51, PMID: 15694174
  • Edwards et al., 2009, J Inherit Metab Dis, 32 Suppl 1:S197-200, PMID: 19562505
  • Genetics Home Reference, 2013, http://ghr.nlm.nih.gov/condition/arginase-deficiency
  • Jain-Ghai et al., 2011, Mol Genet Metab, 104(1-2):107-11, PMID: 21802329
  • Lee et al., 2011, Pediatr Neurol, 44(3):218-20, PMID: 21310339
  • Morales et al., 2019, StatPearls Publishing, PMID: 29493987
  • Scaglia et al., 2006, Am J Med Genet C Semin Med Genet, 142C(2):113-20, PMID: 16602094
  • Sin et al., 2015, J Mol Med, 93(12):1287-96, PMID: 26467175
  • Therrell et al., 2017, Mol Genet Metab, 121(4):308-13, PMID: 28659245