Noonan syndrome

By Medically reviewed by Panel Perubatan Hello Doktor


What is Noonan syndrome?

Noonan syndrome is a genetic disorder that prevents normal development in various parts of the body. A person can be affected by Noonan syndrome in a wide variety of ways. These include unusual facial characteristics, short stature, heart defects, other physical problems and possible developmental delays.

How common is Noonan syndrome?

Noonan syndrome occurs in approximately 1 in 1,000 to 2,500 people. Please discuss with your doctor for further information.


What are the symptoms of Noonan syndrome?

The common symptoms of Noonan syndrome are:

  • A characteristic facial appearance.
  • Short stature.
  • Heart defect present at birth (congenital heart defect).
  • A broad or webbed neck.
  • Minor eye problems such as strabismus in up to 95 percent of individuals.
  • Bleeding problems such as a history of abnormal bleeding or bruising.
  • An unusual chest shape with widely-spaced and low set nipples.
  • Developmental delay of varying degrees, but usually mild.
  • In males, undescended testes (cryptorchidism).

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes Noonan syndrome?

Noonan syndrome is caused by a genetic mutation. These mutations can occur in multiple genes. Defects in these genes cause the production of proteins that are continually active. Because these genes play a role in the formation of many tissues throughout the body, this constant activation of proteins disrupts the normal process of cell growth and division.

The mutations that cause Noonan syndrome can be:

  • Children who have one parent with Noonan syndrome who carries the defective gene (autosomal dominant) have a 50 percent chance of developing the disorder.
  • Noonan syndrome can develop because of a new mutation in children who don’t have a genetic predisposition for the disorder (de novo).

Risk factors

What increases my risk for Noonan syndrome?

A parent with Noonan syndrome has a 50 percent chance (one chance in two) of passing the defective gene on to his or her child. The child who inherits the defective gene may have fewer or more symptoms than the affected parent.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is Noonan syndrome diagnosed?

A diagnosis of Noonan syndrome is usually made after a doctor observes some key signs, but this can be difficult because some features are subtle and hard to identify. Sometimes, Noonan syndrome isn’t diagnosed until adulthood, only after a person has a child who is more obviously affected by the condition. Molecular genetic testing can help confirm a diagnosis.

If there’s evidence of heart problems, a doctor who specializes in heart conditions (cardiologist) can assess the type and severity.

How is Noonan syndrome treated?

Although there’s no way to repair the gene changes that cause Noonan syndrome, treatments can help minimize its effects. The earlier a diagnosis is made and treatment is started, the greater the benefits.

Treatment of the symptoms and complications that occur with Noonan syndrome depends on type and severity. Many of the health and physical issues associated with this syndrome are treated as they would be for anyone with a similar health problem. Taken together, though, the many problems of this disorder require a coordinated team approach.

Recommended approaches may include:

  • Heart treatment. Certain drugs may be effective in treating some kinds of heart problems. If there’s a problem with the heart’s valves, surgery may be necessary. The doctor also may recommend that heart function be evaluated periodically.
  • Treating low growth rate. Height should be measured three times a year until 3 years of age and then once every year until adulthood to make sure he or she is growing. To evaluate nutrition, the doctor will likely request blood tests. If your child’s growth hormone levels are insufficient, growth hormone therapy may be a treatment option.
  • Addressing learning disabilities. For early childhood developmental delays, ask the doctor about infant stimulation programs. Physical and speech therapies may be helpful for addressing a variety of possible issues. In some cases special education or individualized teaching strategies may be appropriate.
  • Vision and hearing treatments. Eye exams are recommended at least every two years. Most eye issues can be treated with glasses alone. Surgery may be needed for some conditions, such as cataracts. Hearing screenings are recommended annually during childhood.
  • Treatment for bleeding and bruising. If there’s a history of easy bruising or excessive bleeding, avoid aspirin and aspirin-containing products. In some cases, doctors may prescribe drugs that help the blood to clot. Notify your doctor before any procedures.
  • Treatment for lymphatic problems. Lymphatic problems can occur in many ways and may not require treatment. If they do require treatment, your doctor can suggest appropriate measures.
  • Treatment for genital problems. If one or both testicles haven’t moved into proper position within the first few months of life (undescended testicle), surgery may be needed.

Other evaluations and regular follow-up care may be recommended depending on specific issues, for example, regular dental care. Children, teens and adults should continue to have ongoing, periodic evaluations by their health care professional.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage Noonan syndrome?

A number of support groups are available for people with Noonan syndrome and their families. Talk to your doctor about finding a support group in your area. Also ask about trustworthy resources on the internet that can direct you to local support groups and sources of information about Noonan syndrome.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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