Arginase Deficiency


Here you’ll find answers to some of the questions that parents often have about this condition. More resources are listed at the bottom of the page. More detailed information, aimed at primary care clinicians, can be found in the Arginase Deficiency and the Arginase Deficiency screening page.

What is arginase deficiency and what causes it?

Arginase deficiency is a rare genetic disorder. It results from the absence of the enzyme arginase 1, which causes ammonia to build up in the body. While the high levels of ammonia are often mild, they can be life-threatening. If untreated, developmental problems and seizures can happen.

What are the symptoms of arginase deficiency?

Infants and young children with arginase deficiency usually seem normal until age 1-4 when they start to show muscle tightness and developmental delay. Many also have microcephaly (small head due to poor brain growth).

How is it diagnosed?

Newborn screening programs test for arginase deficiency, making diagnosis possible very early in the child's life, before symptoms begin. Testing can also be done if arginase deficiency is suspected in older children.

What is the prognosis?

With treatment, the chance for a normal life is excellent, though it is not yet known whether adults with this condition will be problem-free.

What is the risk to other family members and future children?

Arginase deficiency is passed down by a child’s parents when they are both carriers of an abnormal gene for the arginase 1 enzyme. When people have just one such gene, they are called carriers and they don’t have the condition. However, people with two abnormal genes will have it. Because everyone has two copies of all of their genes, one from each parent, the chance that a child of parents who are both carriers will have arginase deficiency are 1 in 4.

What treatments/therapies/medications are recommended or available?

Treatment involves restricting protein in the diet, taking some essential amino acids, and the use of medications to remove ammonia.

How will my child’s and our family’s life be changed?

Your child will need to be on a protein-restricted food plan and take amino acids for the rest of her/his life. Some children may also need to take medication. By following treatment, it is thought that most people will lead a normal life.


Information & Support

Where can I go for further information?

For Parents and Patients


National Urea Cycle Disorders Foundation
This non-profit organization gives support and information that includes medical lectures on urea cycle disorders, nutrition and medication resources, and information about events and conferences.


Argininemia - Information for Parents (STAR-G)
A fact sheet, written by a genetic counselor and reviewed by genetic specialists, for families who have received a diagnosis of arginase deficiency; Screening, Technology, and Research in Genetics.

Argininemia (Genetics Home Reference)
Excellent, detailed review of condition for patients and families; sponsored by the U.S. National Library of Medicine.

Urea Cycle Abnormalities (Medline Plus)
Contains information for families about urea cycle disorders in general; arginase deficiency is one of these.

Genetics in Primary Care Institute (AAP)
Contains health supervision guidelines and other useful resources for the care of children with genetic disorders; American Academy of Pediatrics.

National Newborn Screening & Global Resource Center (NNSGRC)
Fact sheets, data reports, publications, and information for clinicians about genetic screening that includes links to state genetic contacts.

Patient Education

Learn the Signs. Act Early (CDC)
Offers many tools, videos, lists, learning materials, and an app to track a child’s developmental milestones (ages 2 months to 5 years) and act if concerned about progress; Centers for Disease Control and Prevention.

Services in Nevada

Select services for a different state: ID, MT, NM, RI, UT

Newborn Screening Services

See all Newborn Screening Services services providers (1) in our database.

Nutrition, Metabolic

We currently have no Nutrition, Metabolic service providers listed; search our Services database for related services.

Pediatric Genetics

See all Pediatric Genetics services providers (2) in our database.

Pediatric Metabolic Genetics

We currently have no Pediatric Metabolic Genetics service providers listed; search our Services database for related services.

For other services related to this condition, browse our Services categories or search our database.

Authors & Reviewers

Initial publication: October 2012; last update/revision: December 2018
Current Authors and Reviewers: