Noonan Syndrome
Jacqueline Noonan first discoverd Noonan Syndrome over 20 years ago. She noticed children with a rare type of heart defect called valvular pulmonary stenosis often had similar physical characteristics. After studying 833 patients and looking at their congenital abnormalities they started calling the syndrome Noonan Syndrome. Noonan Syndrome is a disorder that causes abnormal development of multiple parts of the body. People can be affected by Noonan Syndrome in various ways. The most common characteristics are facial dysmorphology, congenital heart defects, short stature, bleeding disorders and sometimes mental retardation. Problems with speech and language are also common. There is no specific treatment for Noonan Syndrome.

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Emily, Dezmond & Allison -


Noonan Syndrome is a genetic disorder. Only one of the parents has to carry the gene in order for it to be passed down or it can develop because of a new mutation in children who don't have a genetic predisposition for the disease. "The incidence of Noonan Syndromehas been estimated to be between 1 iin 1000 and 1 in 2500 live births" (Allanson, 1987). It is caused by a defect in one or more of four specific genes: KRAS, PTPN11, RAF1, and SOS1. These genes play a role in the formation of many tissues throughout the body. Defects in these genes cause them to produce proteins that are always active. This constant activation of proteins disrupts the normal process of cell division and growth. In very rare cases people who have Noonan Syndrome characteristics also have another condition called Neurofibromatosis. People with these two conditions have a mutation in the neurofibromin 1 gene. This gene produces a protein that helps keep cells from growing too fast or in a uncontrolled way (Noonan, 2007). There are occasions where all of these genes are undamaged, for these cases the cause is unknown.

Noonan Syndrome Gene
Percentage of all NS Cases
Differentiating Feature(s)
Higher prevalence of pulmonary stenosis and atrial septal defect
Approx. 80% of cases have hypertrophic cardiomyopathy
More cutaneous findings, less short stature, less cognitive delay
More severe cognitive and developmental


  • Unusual facial features are very important in the diagnosis of Noonan Syndrome. These facial features change with age and often become less noticable as an adult.
    • New Born- wide-set and down-slanting eyes, low-set ears, a deep groove and wide peaks in the upper lip, a short neck and a low hairline on the back of the head.
    • Infancy- prominent eyes with a downward slant and thickened lids, and a depressed root of the nose with a wide base.
    • Childhood- lack of facial expression.
    • Adolescence- wide forehead narrowing to a pointed chin, facial features become sharper and the eyes are less prominent, and the neck lengthens to reveal skin webbing.
    • Adulthood- The crease that runs from the edge of the nose to the corner of the mouth becomes apparent and the skin may be wrinkled and appear transparent. (MFMER, 2009)
  • Short stature
  • Heart defects
  • Skeletal malformations
  • Eye/Vision problems - Abnormalities of eyes and lids are very common. The iris is usually pale blue or green. Differences in shape and size of eyes, problems with eye muscles, astigmatism, nearsightedness, nystagmus (rapid movement of the eyeballs) and problems with nerves of the eye are all common
  • Possible hearing loss
    Lymphedema of feet in an infant
    Lymphedema of feet in an infant
  • Feeding and speech problems
  • Bleeding problems
  • Possible mild mental retardation
  • Lymphatic issues - Excess fluid in hands and feet (lymphedema) are most common.
  • Small penis and undescended testicles
  • Sunken chest
  • Delayed puberty
  • Lack of coordination

Systems Review:

Nervous System - The Nervous System is not typically affected by Noonan Syndrome. However, it has been documented that the nerves of the eye may be affected (MFMER, 2009) and also, sensorineural hearing loss, which involves the auditory nerve, may occur ( Van der Burgt, 2007) as a result of Noonan Syndrome.

Respiratory System - The Respiratory System is not directly affected by Noonan Syndrome. However, there are a couple of complications that are associated with Noonan Syndrome that can impact the respiratory system. One possible complication of Noonan Syndrome is Pulmonary Stenosis (Manbir). This is when the pulmonary valve is narrowed so that the right ventricle must pump harder to get the blood through the narrow passage. Over time, this can cause damage to the heart muscles (American).
Individuals, particularly infants, may also suffer from pleural effusion due to the lymphatic system issues (difficulty draining excess fluid from the body) assoicated with Noonan Syndrome. Pleural effusion is a condition in which excess fluid accumulates in the pleural cavity. This limits the expansion of the lungs and causes difficulty breathing.

Phonatory System -
The Phonatory System is not typically affected by Noonan Syndrome. However, since respiration is the energy source for phonation, if a person's respiratory system is compromised due to a Noonan Syndrome complication, they may also have some difficulty with phonation.

Articulatory System -
Noonan Syndrome primarily impacts the articulatory system. The following abnormalities in the articulatory system may be caused by Noonan Syndrome: high-arched palate, poor tongue control, general muscle weakness in the mouth, dental problems (usually malocclusion), an undersized lower jaw, and an anterior skeletal open-bite. Infants may have sucking, swallowing and feeding problems due to a high-arched palate and poor tongue control. They may also suffter from frequent vomiting and reflux issues. Individuals with Noonan Syndrome typically have difficulties with articulation due to muscle weakness in the mouth, however, all of these articulatory system abnormalities may greatly affect articulation.

Auditory System -
Noonan Syndrome causes physical deformations of the ear. "90% of people with Noonan Syndrome have low set, posteriorly rotated ears with a thick helix (outer rim of ear)" (Van der Burgt, 2007). Hearing loss due to otitis media (inflammation of the middle ear) is a frequent complication. "Sensorineural hearing loss is less common, but involves the low frequency range in 10% of patients and the high frequency range in 25% of patients" (Van der Burgt, 2007). Structural anomalies of the inner ear have occasionally been reported and vestibular abnormalities have been described in a single case.

Overall Effect on Speech Production:

There has not been a lot of research regarding speech and language development in children with Noonan Syndrome. However, it is widely accepted that children with Noonan Syndrome often have difficulties with articulation. Some research suggests (Nora et al., 1974) that as many as 72% of individuals with Noonan Syndrome have some articulation difficulties primarily due to weak muscles in the mouth. However, other articulatory system abnormalities (listed above) and hearing loss also contribute to the articulation problems associated with Noonan Syndrome. Children with Noonan Syndrome are often referred to a speech language pathologist in order to develop better muscle control in their mouth.

Individuals with Noonan Syndrome tend to have normal receptive language abilities, however, they may have difficulties with expressive language due to cognitive impairment, hearing impairment and/or articulation difficulties. Expressive language delays are often compounded by a child's tendancy not to speak to others because he/she realizes that others cannot understand them. Therefore, they fail to have the social interactions that are critical for the normal development of speech.