Noonan syndrome is a disease affecting different parts of the body. It is a syndrome that develops due to a congenital genetic abnormality and refers to a disease in which normal development in each part of the body is witnessed. Symptoms are characterized by short stature, congenital heart disease, skeletal and blood circulation abnormalities, various degrees of developmental delay, etc. However, not all patients have similar symptoms. (1)
Life Expectancy Of Someone With Noonan Syndrome
Noonan syndrome is one of the most frequent non-chromosomal disorders, with an approximate global occurrence of 1 in 1000-2500 children. The disease usually gets diagnosed at the age of nine and the patients generally have a normal life expectancy. But serious cardiac disorders in some individuals or the presence of cancer in individuals with circulatory problems may cause early death. (3)
When Noonan syndrome patient is born, he has a nearly normal body weight and size. However, abnormally low levels of growth hormones in these patients lessen the patient’s development.
Most people with Noonan syndrome develop cardiac complications. The most typical feature is the restricted blood flow from the heart to the lungs due to the cardiovascular valve narrowing. Some also have hypertrophic cardiomyopathy, related to enlargement of the heart muscle. Male subjects with the disease in adolescence are late in the puberty phase. Most of the patients are also infertile, so they cannot have kids.
Noonan syndrome can cause a consistent set of signs and symptoms. The disease manifests itself in organs throughout the body. In Noonan syndrome, characteristic facial features are observed. Specifically, the eyes are separated and protruding, the forehead is out, and the facial features are known to change with growth.
The development of cancer can be part of the visible complications of this disease. In particular concerning the development of leukemia in patients with circulatory problems. It is a rare disease whose approximate prevalence ranges from 1/1000 to 1/2500 people. (2)
Common Symptoms Of Noonan Syndrome
Noonan syndrome is characterized by different symptoms visible in various patients. The clinical signs most often found are:
- Unusual facial features (broad forehead, drooping eyelids, narrowed neck size, small cheeks, space widens between the eyes, wide and small nose)
- A small build
- Cardiac abnormalities present at birth
- Children with Noonan syndrome also have abnormalities in the bone formation in the rib cage. This results in a widening of the distance between the nipples. These physical signs can be present during childhood and then diminish in adulthood.
- A reduced body structure is characteristic of this disorder as well. At birth, the child has a normal height. It is around the age of two that development starts to slow down. This abnormal low growth (height) increases during puberty.
Auditory manifestations may also be the characteristic signs of the disease. Other associated problems are:
- Hypertrophic heart disease
- Pulmonary stenosis
- Septal defects (membranes separating the organs)
Some other common symptoms are:
- Behavior problems
- Cryptorchidism: testicular abnormalities
- Deficiencies in learning
- Edema in the lymphatic vessels
- Eye problems
- Food allergies
- Greater risk of bruising and hematoma
- Hypotonia (impairment of muscle tone)
- Problems with the bone marrow
- Development of tumors (particularly in children) (4)
Prevention And Treatment Of Noonan Syndrome
The primary diagnosis of the disease is differential. It consists of the visualization of atypical symptoms in the child as stated above. Genetic tests are conducted in the next diagnostic phase. In most cases, the diagnosis can be confirmed during a blood test.
Other tests also make it possible to confirm or rule out the presence of the disease. These examinations are:
The diagnosis can also be made during pregnancy if the mother and/or father has a family history. Ultrasound tests at the time of pregnancy may detect the presence of this disorder through any abnormalities, such as pleural effusion (fluid build-up in lung membrane), excess amniotic fluid or abnormally large fetal body parts.
The symptomatic treatment plan is often adopted and some surgical intervention may be required to control certain symptoms. (4)
- Tafazoli A, Eshraghi P, Koleti ZK, Abbaszadegan M. Noonan syndrome–a new survey. Archives of medical science: AMS. 2017;13(1):215.
- Noonan JA. Noonan syndrome. Health Care for People with Intellectual and Developmental Disabilities across the Lifespan: Springer; 2016:827-832.
- Hemmati P, Dearani JA, Daly RC, et al. Early outcomes of cardiac surgery in patients with noonan syndrome. Paper presented at: Seminars in thoracic and cardiovascular surgery2019.
- Romano AA, Allanson JE, Dahlgren J, et al. Noonan syndrome: clinical features, diagnosis, and management guidelines. Pediatrics. 2010;126(4):746-759.