Noonan syndrome is a genetic condition that can affect many parts of your child’s body. While symptoms vary widely, they most often include unusual facial features, short stature and heart problems. Early detection and treatment can ease symptoms and prevent complications.
Noonan syndrome is a genetic condition that can affect your child in many ways. While some children born with this condition have mild symptoms, others can have more issues.
Symptoms typically include unusual facial features such as a tall forehead and wide-set eyes, lower-set ears and a shorter neck. Many children born with Noonan syndrome also have short stature (short height compared to those the same age), eye issues, low muscle tone and congenital (from birth) heart disease.
While Noonan syndrome has no cure, your healthcare provider can recommend guidance to keep your child as healthy as possible. Your provider will also work closely with you to help prevent complications or catch them early, so your child can lead a full, active life.
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Anyone can be born with Noonan syndrome. About 50% of people with Noonan syndrome have a parent with the condition. In most cases, a person with Noonan syndrome has a 50% chance of passing the condition on to their child.
Noonan syndrome is a relatively common genetic disorder. It occurs in up to 1 out of every 1,000 to 2,500 people.
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Noonan syndrome occurs most often due to changes (mutations) in certain genes that help your body’s tissues grow and develop. These mutated genes produce proteins that are active longer than they should be. They interfere with proper cell growth and division.
Noonan syndrome may be:
Genetic testing can find an abnormality in almost 80% of people with Noonan syndrome. For the rest, researchers don’t know the exact cause.
Noonan syndrome belongs to a group of related conditions known as RASopathies (raz-OHP-uh-thees). All of the conditions are due to the same type of abnormal cell growth and development and have similar symptoms.
RASopathies include:
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Symptoms of Noonan syndrome vary from mild to life-threatening, depending on the affected part of your child’s body. Most symptoms start when the fetus is developing in the uterus or appear in children before age 11.
Facial features of children with Noonan syndrome often become less noticeable as children get older. They may include:
Other common physical symptoms are:
Many children born with Noonan syndrome have heart disorders (congenital heart disease). They may require immediate treatment or develop symptoms later in life. Heart conditions include:
Noonan syndrome may also cause:
Many children with Noonan syndrome experience slower-than-usual growth in adolescence, although they may be born at a typical length. About 25% have a learning disability, with only some children having an intellectual disability. Around 10% to 15% of children with Noonan syndrome need special education. Noonan syndrome can also cause developmental delays, behavioral issues or speech disorders.
Some children with Noonan syndrome have an increased chance of an unusual childhood leukemia called juvenile myelomonocytic leukemia (JMML) or other childhood cancers. But the overall risk by age 20 is thought to be around 4%.
Your healthcare provider may suspect Noonan syndrome after a physical exam and review of your child’s symptoms. Your provider may order genetic tests to confirm a diagnosis and rule out other conditions.
Tests may include:
Noonan syndrome has no cure. But effective treatments can help you and your child manage symptoms.
Your child’s healthcare team develops a treatment plan for Noonan syndrome based on your child’s symptoms and their severity. Your child may receive:
In some cases, your healthcare provider may recommend surgery. Early diagnosis is important for effective treatment and follow-up care.
Your team may include your pediatrician and a:
Your care team will recommend a treatment that’s right for your child. They’ll monitor and adjust medications or therapies based on your child’s condition and any side effects they’re having.
Nothing you do can reduce your child’s risk of developing Noonan syndrome. It happens because of a genetic change. If Noonan syndrome runs in your family, you can talk to your healthcare provider about prenatal genetic testing.
Most people who have Noonan syndrome lead healthy, independent lives. Your child’s care team will work with you to manage your child’s symptoms and prevent complications.
When Noonan syndrome causes severe congenital heart disease, your child may require surgery and ongoing monitoring to stay healthy and safe. Your healthcare provider can discuss immediate and long-term treatment options with you.
A note from Cleveland Clinic
A medical diagnosis can feel scary when it comes to your newborn baby or growing child. But most children diagnosed with Noonan syndrome have mild symptoms and lead full and active lives. Reach out to your healthcare provider about effective treatment or ongoing care options that fit your child’s needs. Prompt treatment can help ease your concerns and ensure that your child has the best health outcomes possible.
Last reviewed on 01/27/2023.
Learn more about the Health Library and our editorial process.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy