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Arginase Deficiency

Medical information you need to know as an adult with arginase deficiency

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Overview of the Condition:

Arginase deficiency is a rare metabolic condition in which a chemical called arginase does not work correctly in your body. This causes ammonia to build up too much in your blood over time. When ammonia builds up too much, it can cause serious health problems. You can manage arginase deficiency throughout your life with a special low-protein diet, a special medical formula, drug therapy, and ongoing health care.

Other names for arginase deficiency are: argininemia, hyperargininemia, and ARG1 deficiency.

Medical Problems for Babies and Children:

  • If arginase deficiency goes undetected, babies and children may have: abnormal muscle tensing and stiffness, delayed growth, learning delays, tremors, or seizures.
  • On rare occasions, babies and children may show signs of ammonia build-up (also called hyperammonemia) after eating a lot of protein, or after an illness or surgery. Symptoms include vomiting, refusing to eat, and being tired and irritable.
  • Newborns in some US states are now tested for arginase deficiency. If the condition is identified early and treatment is followed carefully, the most serious health problems can be avoided.

Medical Problems for Teens and Young Adults:

  • Teens and young adults with arginase deficiency may have learning disabilities.
  • If you have an illness, fever, surgery, or are pregnant, contact your health-care provider right away.
  • Watch for signs of ammonia build-up including: nausea, vomiting, sleepiness, or unusual problems with your mood or thinking. If you have any of these, get medical care right away.
  • Some teens and young adults with arginase deficiency have anxiety or depression. Counseling and medication can help. If you have anxiety or depression, it is important to get in touch with your health care provider to get treatment.

How to Minimize Medical Problems and Complications:

Fertility and Pregnancy:

  • Arginase deficiency does not affect your ability to have children.
  • Genetic counseling can help you and your partner understand the risks to your children. Your doctor can refer you to a genetic counselor who has a special understanding of your health issues.
  • Pregnant women with arginase deficiency must follow a careful diet with guidance from a dietician.

How To Get Support:

  • Get education support from teachers and specialists at your school.
  • Join a support group with people who have arginase deficiency or similar metabolic conditions. This group of health conditions is called urea cycle disorders.
  • A lot of research is being done on arginase deficiency and other urea cycle disorders. Get up-to-date information about new treatments and discoveries at the Urea Cycle Foundation website: http://nucdf.org/


AAP/AAFP/ACP Transition Clinical Report

Transition Toolkit (New England Consortium of Metabolic Programs)

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National Urea Cycle Disorders Foundation

Acute Illness Protocol for Arginase Deficiency

National Institutes of Health – Genetics Home Reference – Arginase Deficiency

Genetics Referrals:

Clinical Services

Genetic Services

What Next?

Now you can fill out the Medical Health Summary, print it, and save it.  This will help you keep important medical information in one place.


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This Metabolic Condition Basics guide was adapted with permission from the American College of Medical Genetics ACT Sheet

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