Noonan syndrome - Diagnosing Noonan syndrome

Noonan syndrome may be suspected if your GP or paediatrician (doctor specialising in the treatment of children) spots some of the signs and symptoms most commonly associated with the condition.

These include:

• distinctive facial features
• restricted growth (short stature)
• mild learning difficulties
• undescended testicles 
• lymphoedema (swelling of specific parts of the body as a result of a build-up of fluid)

Read more in the characteristics of Noonan syndrome.

However, in some cases, symptoms may not become apparent until the teenage years or adulthood.

In this case, you may be referred to a specialist (a clinical geneticist) for genetic testing. In most cases, Noonan syndrome can be confirmed by a blood test for the various genetic mutations. However, in about 1 in 5 cases, no specific mutation can be found, so a negative blood test will not rule out Noonan syndrome.

Further testing

If Noonan syndrome has been confirmed or is strongly suspected, further tests are needed to establish the extent of the symptoms. These tests will probably include:

• an electrocardiogram (ECG) - where electrodes (small, metallic discs placed on the skin) measure the electrical activity of the heart
• an echocardiogram - where sound waves build a detailed image of the various structures that make up the heart
• educational assessment if required
• blood tests for clotting studies if there is a history of bruising or bleeding
• sight tests - to check for problems such as squints or blurred vision
• hearing tests - to check for problems such as hearing loss caused by otitis media

The echocardiogram may need to be monitored regularly to determine if there is any change in the heart function.