Noonan syndrome

Noonan syndrome is a genetic disorder that causes a wide range of features which can vary from person to person.

The most common features of Noonan syndrome are:

  • heart abnormalities - where a baby is born with congenital heart defects
  • distinctive and unusual facial features, such as drooping eyelids (ptosis) or a wider than usual distance between the eyes
  • restricted growth (short stature)

The severity of these features can range from mild to life-threatening.

Read more about the symptoms of Noonan syndrome.

The condition is usually diagnosed at birth, although milder cases may go undiagnosed until a child gets older.

Noonan syndrome is relatively uncommon. It is estimated that around 1 in 2,500 children are born with it. It affects both sexes and all ethnic groups equally.

Read more about diagnosing Noonan syndrome.

What causes Noonan syndrome?

Researchers have identified eight specific genetic mutations that cause Noonan syndrome. A genetic mutation happens when the normal instructions that are carried in certain genes become scrambled. This means that some of the body’s processes don't work in the normal way.

However, it is unclear exactly how these mutations cause all the symptoms associated with Noonan syndrome.

Read more about causes of Noonan syndrome.

Treating Noonan syndrome

There is currently no cure for Noonan syndrome, so treatment involves trying to manage the various symptoms and complications that can arise from the condition.

The outlook for children with Noonan syndrome depends on how serious their congenital heart disease is (if they have it - around 80-90% of children with Noonan syndrome do). Some types of congenital heart disease are mild and only require careful monitoring. Other types can be life-threatening and require immediate emergency surgery.

However, almost all children with congenital heart disease reach adulthood. Most adults with Noonan syndrome do not require specialist medical care but may benefit from occasional cardiac follow-up. They are usually able to lead full and independent lives.

Read more about treatment for Noonan syndrome.

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