Disorder Zone Archives

 

Noonan Syndrome

Alex Bleyhl

Introduction

Noonan syndrome (NS) is a genetic disorder characterized by distinct facial characteristics, short stature, and congenital cardiac defects. NS is believed to occur in 1 out of every 1,000 live births and it affects both males and females equally. NS can be hereditary and is considered autosomal dominant, where the affected gene only needs to be passed on by one parent. A parent with the defective gene has a 50% chance of passing it on to his or her child. Frequently, however, NS can be a sporadic syndrome (or caused by a new mutation), affecting only one family member. Women appear to pass on the gene three times more often than men.

NS was first described in 1963 by a pediatric cardiologist named Jacqueline Noonan. Dr. Noonan recognized that an unusual heart defect (valvular pulmonary stenosis) was sometimes accompanied by short stature and a characteristic physical appearance with a webbed neck, wide-spaced eyes, and low-set ears.

 

Features and Characteristics

There are many characteristics associated with NS. Not every child has all the characteristics, however, the following is a list of traits that have been reported:

• Hypertelorism (wide-spaced eyes)
• Downward slanting of eyes
• Ptosis (drooping of the eyelids) - lessens with age
• Epicanthal fold (extra fold of skin at the inner corner of the eye)
• Strabismus (crossed eyes)
• Myopia (near sightedness)
• Proptosis (prominence of the eyes)
• Striking blue or blue/green eyes
• Diamond-shaped eyebrows
• Backward, rotated, low-set ears with a thick outer border
• Prominently grooved upper lip
• Small nose with upturned tip
• Micrognathia (small jaw)
• High arched palate
• Dental malocclusion
• Excess neck skin with a low hair line at the nape of the neck in infancy
• Broad or webbed neck as the child reaches puberty
• Tall forehead and oval or round face in infancy - triangular face (broad forehead and pointed chin) in childhood
• Congenital heart defect (valvular pulmonary stenosis, atrial septal defects or ventricular septal hypertrophy)
• Short stature
• Breast bone deformity with a funnel chest
• Widely spaced nipples
• Rounded or slouched shoulders
• Blunt and squared finger tips
• Curly or woolly hair
• Undescended testicles
• Poor weight gain in infancy
• Mild bleeding abnormality
• Difficulty with articulation
• Wide range of mental abilities (mild mental retardation to superior intelligence have been described)

 

Diagnosis

To date, the gene that causes NS has not been identified, therefore, there is no diagnostic test available at this time. A diagnosis of NS must be given on a clinical basis. However, the gene that causes NS has been localized to a region of chromosome 12. The region contains approximately 150 genes, so studies are now underway to identify which gene within this group is responsible for the syndrome.

 

Treatment

There is no cure for NS, but several of the complications associated with the syndrome can be treated. Surgery can be performed to correct chest defects, heart defects, strabismus, and undescended testicles. Medical treatment is available to correct the blood clotting problems, and growth hormone supplementation can be used if there is a deficiency. For some children, special education classes may be necessary and for those with speech impairments, speech therapy may be helpful.

 

What to Expect

Individuals with NS reach adulthood and can live very productive lives. Some marry and have children. In fact, some adults with NS are not diagnosed themselves until they have children of their own with the syndrome.

 

Personal Stories

Alex was born with congestive heart failure and had open heart surgery at five weeks of age due to complications involving the RSV virus. When Alex was 6 weeks old, we brought him home, although he was in and out of the hospital for the first 6 months of life. Although his atrial septal defect and ventricular septal defect were repaired, at 1 year of age he was diagnosed with hypertrophic cardiomyopathy (HCM). At 4 years of age, the HCM mysteriously resolved itself. However, had I known that the most difficult thing would be feeding and not his heart, I would not have believed it! This has been our biggest struggle. It has been four and a half years and we are still dealing with a G-tube! Some days I want to throw in the towel and I don't want to go on tube feeding, watching my son vomit as he heaves and sobs. There are so many thing to say about life with Alex...

The next hardest thing is the effects Alex's health status has had on his siblings. His older brother, Aaron, has had the toughest time, giving up Mom at the beginning, trudging from doctor to doctor, holding cloths to catch the throw up, and having Mom stressed out. All he ever wanted was a little brother to play with. He has waited a long time. Alex's little sister, Alyssa, shares his birthday, as she was born two years later. Alyssa gives me a yearning for a "normal" life. I see the little blocks that she stacks at age 2 and the words that tumble out of her mouth - the ravenous hunger drive she has that comes so naturally.

But I am so blessed... so blessed. For who am I to look upon the smile that crosses Alex's face when he sees me? Alex is unassuming, forgiving, and quite a crack up with humor! He is a pleaser. He is the most social of my kids. Alex can dance with great rhythm! He has surpassed the doctor's expectations in every area (except feeding!) and he is "playin' with the big boys now," as he says. He will be attending a mainstream Christian school in the fall of 2000. He is the sweetest boy I could ever have, and I would never, ever trade the experiences that Alex's life have taught me.

Yes, I get discouraged. I wonder what it would be like to be a family whose eyes are blinded by good health. What kind of person would I be? How many social circles would I get involved in? How many things would fill up my days and thoughts that would take me away from viewing my family as the most important unit and take me away from nurturing? I thank God for giving me only what He knows I can handle, and that is a privilege. I used to think I was on the outside looking in. But I am inside, looking out. Until you have a child or person who needs you like Alex needs me, you are on the outside looking in. Only you don't know it. - Diane Bleyhl

 

Resources

If you are interested in meeting other parents and individuals who are involved in raising a child with Noonan syndrome, a discussion forum is offered. To subscribe to the e-mail list, send an e-mail to listserv@home.ease.lsoft.com, leaving the subject field blank and typing "subscribe noonan-syndrome" (without the quotes).

For more information on Noonan syndrome, please see the following references:

• The Noonan Support Group http://www.noonansyndrome.org
• Noonan Syndrome Society http://www.paston.co.uk/users/maygurney/ns.html
• Online Mendelian Inheritance in Man (OMIM) http://www3.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?163950
• Pediatric Database http://www.icondata.com/health/pedbase/files/NOONANSY.HTM

 

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