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What is Noonan Syndrome ?
Noonan syndrome is defined as a developmental disorder which leads to unusual characteristics like abnormal facial structure, heart problems, short stature, skeletal defects, eye abnormalities and bleeding problems. It has been term after Dr. Jacqueline Noonan.
Noonan’s Syndrome is a rather commonly observed congenital genetic disorder equally affecting both the genders. It is often confused with Turner’s syndrome even though both of these have distinct genetic causes. About 95 percent of individuals with Noonan syndrome have eye abnormalities.
Interestingly, Noonan syndrome has several names including Noonan-Ehmke syndrome, Male Turner syndrome, Pseudo-Ullrich-Turner syndrome, Ullrich-Noonan syndrome, Female Pseudo-Turner syndrome, Familial Turner syndrome, Turner-like syndrome and Turner’s phenotype.
Noonan Syndrome Symptoms
Noonan syndrome is congenital but the distinctive facial characteristics are not noticeable until later. These facial features are obvious only for a few years of childhood and as the child grows these features become less apparent. Only a careful examination can help in recognizing the facial features.
The signs of Noonan syndrome include some of the following features:
- Short stature in nearly 80% of the affected individuals. The growth rate is affected. The Noonan syndrome growth charts helps in the accurate analysis of the growth rate.
- Nearly 95% of the affected individuals suffer from various eye abnormalities.
- Speech and language problems.
- Unusual facial characteristics. Some of these include low-set ears, short webbed neck, widely spaced eyes and triangular face.
- Delay in development of puberty for the genders.
- Heart defects since birth in nearly 50% of the patients.
- Bleeding disorders
- Abnormal chest
- The testes in 50% of affected males are undescended, a condition known as cryptorchidism. This can lead to infertility at later stages.
- Skin problems like affected color and texture.
Noonan Syndrome Pictures
Noonan Syndrome Picture 1 : A female patient with Noonan Syndrome (age = 12 year old) – having Webbed neck and rib deformity and double structural curve.
Image source : Wikipedia.org
Noonan Syndrome Picture 2 : Clinical features
Noonan syndrome Picture 3
Noonan syndrome Picture 4
Noonan Syndrome Life Expectancy
Noonan syndrome congenitally affects 1 in every 1000-2500 children. Though it is among the most common genetic syndromes related to cardiac problems, the severity and range of the characteristics vary greatly. The patients with Noonan syndrome usually have a relatively normal life in case of absence of any serious cardiac complication. The presence of the any cardiac complication increases the risk of early death depending on the severity of the condition.
Noonan Syndrome Causes
Noonan syndrome is caused due to particular genetic mutations. It can either be inherited by the child before birth or can also develop due to some new mutation. So far, four genes have been known to cause noonan syndrome. These are the PTPN11, SOS1, RAF1 and KRAS genes. Any defect in these genes results in continually active production of proteins. Since these genes are important for the formation of various tissues in the body, this continuous protein production affects the regular process of cell division and growth. However, in some patients diagnosed with noonan syndrome, none of these 4 genes undergo mutations which show that there are other genes too yet to be discovered.
Noonan Syndrome Diagnosis
Since there is no specific test to diagnose a condition of Noonan syndrome, it is usually done by identifying the physical abnormalities like the special unusual facial features. Some of the vital signs and symptoms associated with noonan syndrome are not apparent until later in life. This is why the disorder is not usually noticed until adulthood.
If there are any signs of noonan syndrome cardiac problems, the patient is advised to undergo an echocardiogram or electrocardiogram to determine the type and the condition’s severity. In case of affected parents, the noonan syndrome testing includes an ultrasound scan to detect any cardiac problems in an unborn child.
Noonan Syndrome Treatment
The treatment for Noonan syndrome is usually done based on the symptoms, complications, type and severity. The treatment for the symptoms does not vary much from that followed for the general patients. The various disorders associated with the syndrome are treated individually based on the classification.
For some cardiac problems, certain medications prove sufficient whereas a problem involving the valves may require a surgery. The functioning of heart should be evaluated at regular intervals of time.
The growth rate is affected in individuals with Noonan syndrome. If the growth rate is not normal, then a growth hormone therapy is recommended for the child. This boosts the growth hormone levels to a sufficient level. Noonan syndrome leads to eating difficulties too resulting in inadequate nutrition. This slows down the growth rate and hence these eating disorders should be treated as part of Noonan syndrome treatment.
Regular eye examinations are needed for the patients with Noonan syndrome as the vision too is affected. Using glasses can solve the issue in most of the cases. However, severe conditions like cataracts require a surgery.
For patients with undescended or poorly functioning testicles, a replacement is needed. Surgery and human chorionic gonadotrophin injections are some other options for treating problems related to genitals and urinary tract.
Physical and speech therapies can be helpful for the patients facing difficulties in speech and language. Special education programs or teaching strategies help in overcoming various mental disorders due to Noonan syndrome.
Aspirin or related drugs should be avoided in case of any bruising or bleeding. Instead, opt for drugs that help in quick clotting of blood.
Noonan Syndrome Support Group
Noonan syndrome support group is a non-profit organization based in the United States. It provides support, information and understanding to individuals affected by Noonan syndrome. It targets to create and raise awareness and to educate the medical community on the complexities of the syndrome and the way it affects the patients. With help from around the world, the group tries to carry out research related to symptoms, causes, diagnosis, treatment and results. The support group also helps in linking patients, researchers and specialists from around the globe for better understanding of the syndrome.
References
http://en.wikipedia.org/wiki/Noonan_syndrome
http://emedicine.medscape.com/article/947504-overview
