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Inborn errors of metabolism

Phenylketonuria (PKU)

A metabolic disease in which the body cannot process an amino acid called phenylalanine. It is managed with a special diet. It is included in newborn screening in Türkiye.

Included in Türkiye's National Newborn Screening Programme (heel-prick test) since 1987. Source

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

Prepare an emergency card

This page is translated from the Turkish original.

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?

The body cannot break down an amino acid called phenylalanine. The enzyme (a helper protein in the body) that does this job does not work well. Phenylalanine builds up in the blood and the brain. If it is not treated, it damages the brain.

Which symptoms can occur?

Babies often look healthy at birth. If the disease is not treated, these problems may appear over time:

  • Permanent problems with intellectual development (in children who are not treated)
  • Delayed development (common)
  • Seizures, also called fits (common)
  • Behavioral and mental health problems (common)
  • A musty, mold-like body odor (sometimes)
  • Lighter skin and hair (sometimes)

How is it diagnosed?

In most babies, the diagnosis is made soon after birth through newborn screening. A few drops of blood are taken from the heel. If phenylalanine in the blood is high, further blood tests are done.

Treatment and care

The main approach is a special diet that is low in phenylalanine. Protein-rich foods such as meat, milk and nuts are limited. Babies receive a special formula, and blood levels are measured often. With early and well-maintained treatment, the outcome is often good. 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. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. Even if they have no symptoms, testing of brothers and sisters is recommended. Genetic counselling can be sought for future pregnancies.

Source: MedlinePlus Genetics — Phenylketonuria · Orphanet — Phenylketonuria · GOV.UK (NHS yenidoğan taraması) — Phenylketonuria (PKU): detailed information

Key facts

How common is it?
Prevalence: 1-9 per 100 000 (Worldwide) · Birth prevalence: 1-9 per 100 000 (Worldwide)
How is it inherited?
Autosomal recessive
When does it usually start?
Infancy
Gene(s) involved
PAH

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

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 PKU

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 28 active interventional studies for this disease. 19 are recruiting now; 1 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:716 · ICD-11 5C50.0

Codes checked against WHO ICD-11 and Orphanet on October 6, 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.