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Noonan Syndrome
Monday, 18 August 2003
Monday, 12 January 2004


Noonan’s Syndrome is a genetic condition that affects the heart, growth, mental and physical development, and clotting of the blood.


Noonan’s syndrome occurs equally in both males and females. The incidence is 1/1000 live births.

Signs and Symptoms

The characteristics of the disorder vary among different individuals. A person who carries the gene for Noonan’s Syndrome may or may not exhibit the following signs and symptoms associated with the disorder. Clinical features include: Head and Facial: Drooping eyelids, downward slanting eyes, widely spaced eyes, diamond shaped eyebrows. Broad forehead, flat nasal bridge, deeply grooved area between nose and upper lip, high arched palate, small chin, low-set and backwardly rotated ears, webbed neck, extra skin at nape of neck, low hairline, hearing loss. Caved in chest or protruding “pigeon-like” chest, curvatures of the spine along with a hump, hunched back, sideway deviation of the forearm, short stature with abnormal body proportions Multiple birth defects of the heart frequently found in newborns Failure of the testicles to descend into the scrotum Developmental delay with language delay, learning disabilities, mental retardation (25%)

Possible Causes

The syndrome is inherited in an autosomal dominant pattern, which means that if one parent (either mom or dad) carries the gene for the syndrome, there is a 50/50 chance that the gene will be passed on to the child. However, once the gene is passed on, expression of the gene is variable, meaning that the severity of the symptoms exhibited by individuals with Noonan syndrome will be different. It is possible that a child who inherits the gene may show most of the signs or symptoms of the syndrome, or a child may have mild symptoms or even no symptoms at all. It is possible for people to carry the Noonan syndrome causing gene, and never be diagnosed with the disease. Noonan syndrome may also be caused by a sporadic mutation that arises in the gene and it is unknown why this occurs.


Presently the diagnosis of Noonan syndrome is based on clinical features, since a diagnostic test is not yet available. However, the genes which cause the syndrome have been linked to chromosome 12, and once the genes are cloned we will be on our way to discovering a diagnostic test for Noonan syndrome.


Treatment of Noonan Syndrome is geared toward the symptoms of the affected individual. Cosmetic surgical procedures can be performed for facial characteristics to enhance a child’s self esteem and social acceptance. Surgery is also available for the bone abnormalities of the chest and back, especially if they compromise breathing and postural functions. Surgical correction of heart defects is essential to preserve life. Developmental delays and learning disabilities are addressed in special school programs along with speech therapy for language delays.


The life expectancy for persons with Noonan syndrome is generally good, and is primarily dependent on the severity of the cardiac problems.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.


E-Medicine A well-written summary of the syndrome. >> OMNI. This site has an online booklet on Noonan’s Syndrome that is geared toward individuals with the syndrome and their families. Type Noonan syndrome into the search field and it will bring you to the title “Noonan Syndrome Booklet.” Click on this to view the booklet. >> The Rasopathies Foundation and Noonan Syndrome Foundation are support for the families

Google Search for Noonan Syndrome

References and Sources