Arginase Deficiency - Description

Other Names

ARG1 deficiency


270.6, disorders of urea cycle metabolism

ICD-10-CM Code: E72.21


Arginase deficiency is the least common of the urea cycle disorders. It results from the absence of the enzyme arginase 1, which breaks down arginine to ornithine and urea, leading to episodic hyperammonemia. Although the hyperammonemia is usually mild, it can be life-threatening. Infants and young children with this disorder usually appear completely normal until age 1-4 when they begin to show spasticity and developmental delay. Many also develop microcephaly. If untreated developmental regression and seizures occur in the majority of individuals.


Arginase deficiency is an autosomal recessive disorder. There are certain geographical areas, such as northern Mexico [Ibarra-González: 2010] or the French Canadian population in northern Quebec [Qureshi: 1983] where it appears to be more common and/or more severe. The family history may reveal consanguinity. The only gene known to be involved in clinical arginase deficiency is ARG1, which can be tested for clinically. Arginase Deficiency (Genetics Home Reference)


The prognosis is excellent if treatment with a restricted protein diet and nitrogen scavenging medications is begun before the onset of symptoms. Once children show symptoms, treatment may help stabilize the process but does not usually reverse the symptoms.


Arginase deficiency has an estimated incidence of 1 in 2,000,000 live births [Nagata: 1991] [Naylor: 1977] and it affects 3/7,000 institutionalized individuals with mental retardation. [Naylor: 1977]

Arginase Deficiency Module Authors

Author: Nicola Longo, MD, PhD - 10/2011
Compiled and edited by: Lynne M Kerr, MD, PhD - 10/2011
Content Last Updated: 12/2015

The authors listed above are responsible for the overall Arginase Deficiency Module. Authors contributing to individual pages in the module are listed on those pages.

Page Bibliography

Ibarra-González I, Fernández-Lainez C, Vela-Amieva M.
Clinical and biochemical characteristics of patients with urea cycle disorders in a developing country.
Clin Biochem. 2010;43(4-5):461-6. PubMed abstract

Nagata N, Matsuda I, Oyanagi K.
Estimated frequency of urea cycle enzymopathies in Japan.
Am J Med Genet. 1991;39(2):228-9. PubMed abstract

Naylor EW, Orfanos AP, Guthrie R.
A simple screening test for arginase deficiency (hyperargininemia).
J Lab Clin Med. 1977;89(4):876-80. PubMed abstract

Qureshi IA, Letarte J, Ouellet R, Larochelle J, Lemieux B.
A new French-Canadian family affected by hyperargininaemia.
J Inherit Metab Dis. 1983;6(4):179-82. PubMed abstract