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Noonan Syndrome – Causes Symptoms And Treatment

Verified By Apollo Doctors September 15, 2021 1806 0
Noonan Syndrome
Noonan Syndrome


Noonan syndrome is a genetic disorder that prevents the normal development of various body parts. It is a genetic condition 

About Noonan syndrome

Noonan syndrome is a genetic mutation often characterized by physical deformities. In most cases, it transfers from the parents to the offspring. According to the latest research, 1 in 1000 to 1 in 2500 babies suffer from Noonan syndrome.

Symptoms of Noonan syndrome

The symptoms of Noonan syndrome vary greatly,

Change in facial features is one of the most visible symptoms. These include:

  • Backwards rotated and low set ears
  • Wide eyes with drooping eyelids with pale blue or green iris
  • Large head with a prominent forehead 
  • Low hairline 
  • Crooked teeth
  • Droopy face
  • Nose with wide base and bulbous tip
  • Hearing problem 
  • Rapid eyeball movement 
  • Cataract
  • Sparse hair
  • Mouth with a  groove between the nose and the mouth and wide peaks in the upper lip. 
  • Highly arched palate and small lower jaw 

Many people who are diagnosed with Noonan syndrome also face growth issues, such as,

  • Eating difficulty 
  • Abnormal weight 
  • Hormone deficiency 
  • Short stature 
  • Delayed puberty 

Some of the other conditions seen in people suffering from Noonan syndrome are,

  • Thickening of heart muscles 
  • Irregular heartbeat
  • Hole in the heart
  • Spine deformity
  • Undescended testicles (cryptorchidism)
  • Wide-set nipples
  • Lymphatic conditions 
  • Excessive bleeding when hurt
  • An oddly shaped chest often with raised sternum (pectus carinatum) or sunken sternum (pectus excavatum)
  • Short neck, often with prominent neck muscles (trapezius) or extra folds of skin (webbed neck)
  • Increased risk of learning disabilities as well as mild intellectual disability
  • Cataracts
  • A variety of emotional, mental and behavioral issues that are generally mild
  • Problems with the eye muscles like strabismus (cross-eye)
  • Curly, coarse hair or sparse hair
  • Nystagmus (Rapid movement of eyeballs)
  • Lymphedema (excess fluid on the back of hands or top of the feet)
  • Refractive problems like myopia (nearsightedness), hyperopia (farsightedness), or astigmatism


Causes of Noonan syndrome

The main reason behind Noonan syndrome is a genetic mutation. The mutation can be on more than one gene. The following are the two reasons for these genetic defects:

  • Random: it can be a new genetic mutation that does not have any genetic predisposition.
  • Inherited: children whose parents are affected or carry the defective gene.

When to see a doctor for Noonan syndrome?

Symptoms of Noonan syndrome are quite visible. If you see any of the aforementioned signs or symptoms, your child may have Noonan disorder. In this case, you must see a doctor. They may further decide the treatment or refer you to a geneticist.

Risk factors for Noonan syndrome

Children whose parents or close family members have Noonan syndrome are more likely to be diagnosed with this genetic disorder.

Complications in Noonan syndrome

Noonan syndrome requires good care and treatment. If left unattended, it can result in the following complications:

  • Complications in the lymphatic system: the fluid from the lymph gets stored around various organs in the body like the heart, lungs, etc.
  • High chances of cancer: there are higher chances of cancers like leukemia and tumors.
  • Urinary tract problems: due to structural abnormalities in the kidney, the chances of urinary tract complications increases.
  • Development delays: the proper development of the physical and mental features take time. They require special attention.
  • Bleeding: excessive bleeding is not diagnosed until the patient undergoes a severe injury or operation. 

Prevention of Noonan syndrome

There are no specific prevention measures for Noonan syndrome. In many cases, it occurs randomly.

You can talk to your doctor or a genetic counselor about your family history.

What are the treatment options for Noonan syndrome?

A Noonan syndrome diagnosis is made usually after a doctor observes some key signs and symptoms. However, diagnosis can be difficult as some features are subtle and hard to identify. At times, mild cases of Noonan syndrome fail to be identifies until adulthood, only after an individual has a child who is more obviously affected by the condition. Molecular genetic testing can help confirm a diagnosis.

If the syndrome is severe, the signs may be visible at an early age.

Treatment for Noonan syndrome involves treating the symptoms as genetic mutations cannot be treated. The common approaches followed by doctors are,

  • Lymph complications: the treatment for the lymphatic system varies. It may or may not require specific treatment.
  • Heart problems: for heart-related problems, a regular check-up is important. Minor disorders require drug treatment while for severe cases, surgery is the best treatment.
  • Vision and hearing disability: ear screening and eye tests are suggested every two years. Spectacles, hearing aids, and surgery are the suggested way of treating vision and hearing disabilities.
  • Genital issues: for undescended testicles and other genital problems, surgery is recommended.
  • Learning disability: infant stimulation programs, speech therapies, individual teaching strategies, etc. may help in overcoming learning disabilities.
  • Bruising and bleeding: if you notice unusual bruising and bleeding, avoid taking aspirin or other similar medicines. Your doctor will suggest medicines for blood clots. 


Noonan syndrome is a genetic condition that is present from birth. People with Noonan syndrome have three times the higher mortality rate. It requires proper care and attention.

Frequently Asked Questions (FAQs)

What is the life expectancy of someone with Noonan syndrome?

The life expectancy of a person with Noonan syndrome is similar to an average person.

Can Noonan syndrome symptoms be very mild?

The symptoms of Noonan syndrome vary greatly. They differ from mild to severe.

Can Noonan syndrome affect learning capacity?

Noonan syndrome can affect a person physically and mentally. In severe cases, it can hamper visual processing, memory, communication, learning capacity, etc.

How do I know that my child has Noonan syndrome?

The signs and symptoms of Noonan syndrome are generally visible in adults. In children, the signs are only seen in extreme cases. You can see changes in their physical appearance or behavior.

Verified By Apollo Doctors
At Apollo, we believe that easily accessible, reliable health information can make managing health conditions an empowering experience. AskApollo Online Health Library team consists of medical experts who create curated peer-reviewed medical content that is regularly updated and is easy-to-understand.

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