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Inborn errors of metabolism

Arginase deficiency (argininemia)

An inherited urea cycle disorder. Arginine and ammonia slowly build up in the blood. It often causes stiffness in the legs and developmental delay.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

Orphanet has a guideline for emergency doctors for this disease (language: French). See on Orphanet

Prepare an emergency card

This page is translated from the Turkish original.

This disease is followed through the “Inborn errors of metabolism” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

Arginase is an enzyme that carries out the last step of the urea cycle. In this disease, the enzyme is missing or works poorly. An amino acid called arginine builds up in the blood. Ammonia may also rise. This build-up mainly affects the nervous system.

Which symptoms can occur?

Babies usually look healthy in the first months. Symptoms generally begin between 1 and 3 years of age.

  • Stiffness in the legs, walking on tiptoe (common)
  • Slowed growth
  • Developmental delay and loss of skills already learned
  • Seizures (fits)
  • Tremor and balance problems
  • Vomiting and irritability after protein-rich meals or illness (sometimes)

How is it diagnosed?

The levels of arginine and ammonia in the blood are measured. The diagnosis is confirmed with a genetic test. If needed, the enzyme is measured in red blood cells. In some countries, it is found through newborn screening.

Treatment and care

Care is led by a metabolic team. The main approach is a special diet that limits protein and arginine. The amino acids the body needs are given through a special formula. Treatments that help remove nitrogen may be used. In Europe and the USA, there is an approved enzyme treatment specific to the disease. Physiotherapy is important for the stiffness. Blood levels are checked regularly. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through recessive inheritance. The mother and father are usually healthy carriers. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. In marriages between relatives, the chance of carrying the same gene is higher. Genetic counselling is recommended for the family.

Source: MedlinePlus Genetics: Arginase deficiency · NORD: Arginase-1 Deficiency · EMA: Loargys (EPAR)

Key facts

How common is it?
Prevalence: <1 per 1 000 000 (Europe)
How is it inherited?
Autosomal recessive
When does it usually start?
Childhood, Infancy
Gene(s) involved
ARG1

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

For all rare diseases: Nadir Hastalıklar Federasyonu

Links checked on October 8, 2026.

Guides related to this disease

  • Special diets and medical nutrition · Metabolic diet, blood monitoring, medical formula and SGK report, sick-day plan, tube feeding and swallowing problems, school meals, supplement warning
  • Rare disease at school · Telling the school, medicines and emergency plan, inclusion and BEP, support education room, absences, LGS/YKS arrangements, peer bullying.

Support and help

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about Arginase deficiency

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

  • Could this trial be suitable for us?
  • If we take part, how would current treatment and check-ups be affected?
  • Where does the trial take place, and how are travel and accommodation handled?
  • What happens if we want to leave the trial?

ClinicalTrials.gov lists 1 active interventional study for this disease. None is recruiting right now; none has a site in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

See all studies on ClinicalTrials.gov · Joining clinical trials

Inborn errors of metabolism: other news

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:90 · ICD-11 5C50.A2

Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.

The information on these pages is for general information only and does not replace medical advice. Talk to your doctor about diagnosis and treatment decisions. In an emergency in Türkiye, call 112.

Every update is based on an open source and labeled with its level of evidence. No advertising and no drug brand names. Our scientific principles

This page was translated from Turkish by the Doktorclub editorial team.