Noonan Syndrome

What is Noonan Syndrome?

Noonan syndrome is a genetic condition that is part of a larger group of conditions called RASopathies. RASopathies arise when something goes wrong in a pathway involved in the way the cells of our bodies communicate the information they need to function properly. Since the cells of our bodies make up our tissues, organs and organ systems, RASopathies can have widespread effects on growth, development and health.

Noonan syndrome occurs in about 1 in 1,000 to 1 in 2,500 of live births. Since Noonan syndrome is a genetic disorder, it can be passed down from parent to child. Yet, in three out of five cases, the genetic change that causes Noonan syndrome is brand new (de novo) and occurs for the first time in the child affected by the condition.

What Causes Noonan Syndrome?

Noonan syndrome occurs due to a genetic change (also called a mutation or genetic variant) in one of more than ten different genes that are linked to the condition. Changes in the PTPN11 gene are the most common and identified in about half of all cases. However, for about one in five people with a clinical diagnosis of Noonan syndrome a specific genetic change is not identified. This is because we are still learning new information about its causes.

What Are the Signs & Symptoms of Noonan Syndrome?

Noonan syndrome is typically diagnosed in infancy or childhood. The specific features each person has can be different, even within the same family. Below is a summary of the most common features seen in Noonan syndrome.

How Is Noonan Syndrome Diagnosed?

A doctor who specializes in this disorder will complete an evaluation to confirm a diagnosis of Noonan syndrome. It is diagnosed using the clinical features outlined above and then often confirmed with genetic testing. Genetic testing is done on a blood sample from the child. The purpose is to identify DNA changes in one of the genes associated with Noonan syndrome.

How Is Noonan Syndrome Treated?

There is no single treatment for Noonan syndrome. Treatment plans are created by a healthcare team with input from the patient and their family. Some symptoms may require more regular follow-up with specialists than others. For example, heart problems associated with Noonan syndrome are followed more closely by a heart specialist (cardiologist).

Specific recommendations for care may also depend on age. Follow up with specialists can help inform appropriate screening and testing recommendations for common health issues that may affect someone with Noonan syndrome.

Early intervention programs are a useful support resource to help address the developmental differences often seen in children with Noonan syndrome. In some cases, children with Noonan syndrome may need additional support in school and benefit from an individualized education program (IEP).

What Are the Long-Term Effects of Noonan Syndrome?

One of the reasons it is important to confirm a diagnosis of Noonan syndrome as early as possible is because the condition varies widely from person to person. As a result, the life expectancy also differs among people who have Noonan syndrome. Congenital heart defects can lead to a shortened life span.

Although some children may have more serious health issues than other, most children with Noonan syndrome meet their developmental milestones. As adults, most people with Noonan syndrome function well.

Some people with Noonan syndrome have bleeding problems. These problems have a variety of causes and are treated according to their cause. Additionally, delayed or reduced growth is often treated with growth hormone therapy which can help increase the rate of growth for a child with Noonan syndrome.


Our team works closely with researchers who study RASopathies, like Noonan syndrome. Thus, we are informed of cutting-edge technology and treatments that may benefit the children in our care. We can connect interested children and families with opportunities to participate in research studies that can help us better understand the RASopathies and possibly contribute to the discovery of future treatments.

Appointment/Referral Information

To schedule a first-time or return appointment, please call the Division of Genetics directly at 312.227.6120.


For more information, please call our Clinic Coordinator, Carolyn Raski at 312.227.4391.


Noonan syndrome can bring medical challenges and significant stress in the lives of those who know and love someone with the condition. The below groups and research-based resources can help provide support for families and those affected by Noonan syndrome.

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