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Inborn errors of metabolism

Isovaleric acidemia

An inherited metabolic disease. The body cannot break down a building block called leucine. During an episode, a sweaty-feet odor, vomiting and weakness can occur.

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, English). 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?

Leucine is a building block found in many proteins. The enzyme that breaks it down works poorly or not at all. Isovaleric acid and similar substances build up. This buildup can damage the brain and nervous system.

Which symptoms can occur?

Severity ranges from no symptoms at all to severe illness. In about half of the babies found through screening, the course is very mild.

  • Difficulty sucking and vomiting in the first days
  • Weakness and sleepiness
  • Seizures, also called fits
  • An odor like sweaty feet during an episode
  • Poor weight gain and slow growth
  • Developmental delay
  • Reluctance to eat protein-rich foods

How is it diagnosed?

In many countries, it is found through expanded newborn screening. Blood and urine tests guide the diagnosis. The diagnosis is confirmed with a genetic test.

Treatment and care

A low-protein diet that restricts leucine and a special formula are used. The doctor may recommend some nutritional supplements. On sick days, protein is reduced for a short time and sugary foods are given. A child who cannot eat may receive sugar into a vein in hospital. With treatment started before symptoms appear, development is often normal. 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. When relatives marry, the chance that two carriers have children together is higher. Genetic counselling guides the family.

Source: MedlinePlus Genetics: Isovaleric acidemia · NORD: Isovaleric Acidemia

Key facts

How common is it?
Prevalence: 1-9 per 100 000 (Europe)
How is it inherited?
Autosomal recessive
When does it usually start?
Adolescence, Adulthood, Childhood, Infancy, Newborn period
Gene(s) involved
IVD

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.

We could not find a patient association specific to this disease.

For all rare diseases: Nadir Hastalıklar Federasyonu

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 Isovaleric acidemia

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.

ClinicalTrials.gov currently lists no active interventional studies for this disease. Last checked: October 7, 2026.

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:33

No separate ICD-11 code; WHO classifies this disease under: 5C50.E0

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.