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Genetic syndromes and other conditions

Noonan syndrome

A genetic condition present from birth that affects many organs. It causes short stature, heart problems and a typical facial appearance.

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 “Genetic syndromes and other conditions” 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?

A signalling pathway that controls cell growth is overactive. This pathway is called the RAS/MAPK pathway. The problem is most often caused by a change in the PTPN11 gene. The face, height, heart, blood clotting and skeleton can be affected.

Which symptoms can occur?

Symptoms vary a lot from person to person. The following may be seen:

  • Heart problem present from birth, most often narrowing of the lung valve (common)
  • Short stature (in 50 to 70 percent)
  • Widely spaced eyes, low-set ears that are rotated backwards
  • Short or webbed neck
  • A tendency to bleed, such as easy bruising or nosebleeds
  • A sunken or protruding chest
  • Undescended testes and delayed puberty in boys
  • Feeding difficulties in infancy

How is it diagnosed?

The diagnosis is usually considered at birth or in infancy, based on examination findings. A heart ultrasound and an ECG are done to check the heart. Blood tests look for a clotting problem. A genetic test confirms the diagnosis.

Treatment and care

Treatment is planned according to the problems seen in each person. Specialists in children's health, the heart, blood and hormones work together. Heart problems may need medicine or surgery. Growth hormone treatment can be used for short stature. Undescended testes are corrected with surgery. The risk of bleeding is assessed before any operation. Speech therapy, physiotherapy and special education provide support. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through dominant inheritance. This means one copy of the changed gene is enough. For each child of an affected parent, the chance is 1 in 2. Because the signs can be mild, close family members may also be examined. Genetic counselling is recommended.

Source: MedlinePlus Genetics: Noonan syndrome · NORD: Noonan Syndrome

Key facts

How common is it?
Prevalence: 1-5 per 10 000 (Worldwide)
When does it usually start?
Before birth, Childhood, Infancy, Newborn period
Gene(s) involved
PTPN11, BRAF, SOS1, KRAS, RAF1, NRAS

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

  • 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 Noonan

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 8 active interventional studies for this disease. 3 are recruiting 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

Genetic syndromes and other conditions: 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:648 · ICD-11 LD2F.15

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.