What is the life expectancy of someone with Noonan syndrome?

The long-term prognosis of people with Noonan syndrome is variable.
The long-term prognosis of people with Noonan syndrome is variable.

There is a wide range in the severity of signs and symptoms in people with Noonan syndrome (NS). Therefore, the prognosis (long-term outlook) of this disease may vary in every case.

NS is a genetic (heredity) disorder. It may be diagnosed during the routine first-trimester sonography during the pregnancy if the fetus (unborn) has cysts around the neck or nuchal abnormalities (fluid under the neck fold in utero).

It may be diagnosed at birth as well with genetic testing.

Although most people reach adulthood, the risk of blood cancer is higher in these individuals than in the normal population. These kids may also have heart defects, the most common being pulmonic stenosis.

In the absence of a large, longitudinal study, reliable information about long-term morbidity and mortality is lacking. However, those with heart failure around two years of age have a poor chance of living a long life.

The life expectancy of a person with NS is likely to be normal if serious heart defects are absent. About 50% of people with NS have a heart defect since birth such as a hole in the heart (patent ductus arteriosus), heart valve hardening (stenosis), etc.

Some affected children may also have other ongoing health problems such as problems urinating, blood disorders, etc. However, with special care and counselling, the majority of children with NS grow up and function normally as adults.

What is Noonan syndrome?

Noonan syndrome (NS) is a genetic (heredity) condition that affects multiple body systems of a child. A child/person born with NS can be seen with characteristic mildly unusual facial features and many other defects such as 

  • Heart defects
  • Short stature/growth issues
  • Triangular face/micrognathia (a small lower jaw)
  • Feeding and digestive issues
  • Bleeding problems
  • Skeletal defects
  • Failure to thrive
  • Hypertelorism (an increased distance between two body parts)
  • Pectus excavatum (the child’s breastbone sinks into the chest)
  • Learning disorders and lower IQ than peers
  • Delayed milestones
  • Unexplained chronic pain
  • Chiari malformation (the brain tissue extends into the spine)
  • Hypotonia (decreased muscle tone)
  • Teeth and dentition problems
  • Ptosis (drooping of the upper eyelid)
  • Laryngomalacia (poor development of the voice box)
  • Tracheomalacia (collapse of the airway while breathing)
  • Eye issues
  • Cancer, especially of the blood

A person with NS may not have every feature or may present with varying degrees. Most children with NS have normal intelligence, but about one-third may have a mild intellectual disability. Most children with NS are diagnosed with heart defects.

What are the causes?

Noonan syndrome (NS) is caused by faulty genes (basic physical and functional unit of heredity). Around 75% of the cases are inherited (run in their families). These faulty genes can be transmitted from the parent to their child. Each child of a parent who carries these faulty genes has 50% chances of inheriting the gene and developing this condition. There is no evidence of environmental factors such as diet or exposure to radiation that can cause any of these changes in genes. Sometimes, there may be no family history.

It is seen in about 1 in 1,000 to 1 in 2,500 children. It affects both men and women.

What are the treatment approaches for Noonan syndrome?

Currently, there is no cure for Noonan syndrome (NS). However, the multidisciplinary treatment approach and proper management of disease conditions may ease some of the associated issues with NS. If your child has been diagnosed with NS, the treatment options may include the following

  • Careful screening of your child can be done for mild heart irregularities on an outpatient basis.
  • Severe heart structural defects can be corrected with a surgery.
  • Feeding problems can be managed by inserting a nasogastric (a tube in the child’s nose down the food pipe and into the stomach).
  • Shortsightedness can be corrected with prescription glasses.
  • Certain regular injections of growth hormones may help your child achieve a more normal height. However, it is controversial.
  • Undescended gonads (testicles, which are the male reproductive organs) can be corrected by surgery.
  • Seizures can be managed with anticonvulsant medications.
  • In the case of communication skill problems, speech therapy may help to improve your child’s speech and communication skills.
  • About 10% of children with NS may need special education to overcome learning issues.
  • Mild blood clotting problems can be managed with regular medications.
  • Dental structural defects and malpositioning can be corrected with dental surgeries and braces to a certain extent.
  • Ear problems such as a glue ear can be managed by inserting a grommet (a drainage tube) inside the ear.
  • In some cases, appropriate behavior management may help.

Because every NS child shows variability in presentation, multidisciplinary care is necessary to manage these conditions. It is essential that conditions such as developmental disabilities are identified and addressed early and managed carefully.

You should speak to a genetic counsellor if you, your child or a member of your family have been diagnosed with NS or if NS runs in your family. A genetic counsellor may help with better approaches to managing the condition and may also support a family in finding resources.

Health Solutions From Our Sponsors

Medically Reviewed on 11/11/2020
References
Medscape Medical Reference

Pediatric Reports


Journal of the National Medical Association


American Family Physician


NHS


NORD




National Human Genome Research Institute


Cleveland Clinic


Mayo Clinic