Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

Noonan syndrome can be caused by a genetic mutation in any one of several different genes.

Noonan syndrome can be caused by a genetic mutation in any one of several different genes.
beginning of content

Noonan syndrome

3-minute read

Noonan syndrome is a rare genetic condition present from birth. Most people affected by the syndrome can lead a normal life, although some treatments and therapies may be needed, especially in childhood.

What is Noonan syndrome?

Noonan syndrome is a genetic condition that causes a distinctive appearance and a range of health problems. People with Noonan syndrome may be mildly affected, or more severely affected. How the disorder affects people with Noonan syndrome can change as they get older.

Noonan syndrome is caused by a genetic mutation in any one of several different genes. In about half of all cases the condition is inherited, although the parent who passed the condition on to their child may not even know that they carry the faulty gene because they show no signs of the disorder.

Symptoms of Noonan syndrome

Noonan syndrome develops in a baby before birth. Sometimes, the disorder is diagnosed straight away, but some children with mild symptoms aren't diagnosed until they get older.

Children with Noonan syndrome often have medical problems such as heart defects, bleeding (clotting) abnormalities and bone deformities. They are usually shorter and may have low muscle tone.

They can also have a distinctive appearance, including:

  • drooping or hooded eyelids
  • eyes that slope or are widely spaced
  • brilliant blue or blue-green eyes
  • a flat bridge of the nose
  • strongly arched (diamond-shaped) eyebrows
  • low-set ears that tilt back
  • coarse, curly hair with a low hairline at the neck
  • a short neck with extra skin folds at the back

Some children with Noonan syndrome may experience intellectual disability or behavioural problems, such as clumsiness or irritability.

As babies with Noonan syndrome grow, their symptoms can change and may become less noticeable as they reach adulthood.

Diagnosing Noonan syndrome

Diagnosis is usually based on the child’s appearance and health problems, and confirmed with genetic testing. This will involve a blood test, in some cases, further tests may be needed, such as heart investigations including an electrocardiogram (ECG) and echocardiogram (ultrasound).

If you are expecting a baby, you might be able to have prenatal tests done to test your unborn baby for Noonan syndrome.

Living with Noonan syndrome

Most children with Noonan syndrome go on to lead normal lives in adulthood. However, a child newly diagnosed with the disorder may need a number of treatments, and regular tests to monitor their condition over time. The types of treatment and support required will depend on the problems they experience.

Where to go for help

If you have concerns, talk to your doctor. Additional support may also be available from:

More information

Visit our genetic disorders guide to learn more about genes, types of genetic disorders and where to go for help and more information.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: August 2018

Need more information?

These trusted information partners have more on this topic.

Top results

Noonan syndrome - Better Health Channel

Noonan syndrome is a genetic condition that usually includes heart abnormalities and characteristic facial features.

Read more on Better Health Channel website

Congenital heart defects

Congenital heart defect (CHD) or congenital heart anomaly is a defect in the structure of the heart and great vessels that is present at birth

Read more on WA Health website

Rare Cancers Australia - Directory - Childhood Rhabdomyosarcoma

Rare Cancers Australia is a charity whose purpose is to improve the lives and health outcomes of Australians living with a rare or less common cancer.

Read more on Rare Cancers Australia website

Undescended testes (cryptorchidism) | HealthEngine Blog

Cryptorchidism refers to undescended testes. Usually the testes descend from the abdomen to the scrotum before or in the first year after birth.

Read more on HealthEngine website

Cardiomyopathy | HealthEngine Blog

Cardiomyopathy refers to a heart condition or abnormality of the heart which causes inflammation, weakening the heart so it cannot pump blood efficiently.

Read more on HealthEngine website

Heart abnormality birth defects - Better Health Channel

Some congenital heart defects are mild and cause no significant disturbance to the way the heart functions.

Read more on Better Health Channel website

Rare Cancers Australia - Directory - Childhood Acute Myeloid Leukemia/Other Myeloid Malignancies

Rare Cancers Australia is a charity whose purpose is to improve the lives and health outcomes of Australians living with a rare or less common cancer.

Read more on Rare Cancers Australia website

Juvenille Myelomonocytic Leukaemia

What isjuvenille myelomonocytic leukaemia (JMML)? JMML is a very rare childhood blood cancer. Though JMML can be considered a chronic form of leukaemia, there are many distinguishing clinical features of JMML that are absent in the types of chronic leukaemia found in adults. The World Health Organisation has defined

Read more on Leukaemia Foundation website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Government of South Australia, health department logo Tasmanian government logo Government of Western Australia, health department logo