Noonan syndrome (NS) is a relatively common autosomal dominant congenital illness and is named after Jacqueline Noonan, a pediatric cardiologist. It’s known as the male version of Turner’s syndrome nonetheless, the genetic causes of Noonan syndrome and Turner syndrome are different and both females and males are affected. The main characteristics include congenital heart defect (typically pulmonary valve stenosis with dysplastic pulmonary valve additionally atrial septal defect and hypertrophic cardiomyopathy), short stature, learning issues, pectus excavatum, impaired blood clotting, and a feature configuration of facial features such as a webbed neck and a flat nose bridge. NS is a RASopathy, also is just one of several disorders that are brought on by a disturbance of RAS-MAPK signaling pathway.
Noonan syndrome is a genetic disorder that prevents normal development in various parts of the body. A person can be affected by Noonan syndrome in a wide variety of ways. These include unusual facial characteristics, short stature, heart defects, other physical problems and possible developmental delays.
Management of Noonan syndrome focuses on controlling the disorder’s symptoms and complications. Growth hormone may be used to treat short stature in some people with Noonan syndrome.
Symptoms of Noonan syndrome
Signs and symptoms of Noonan syndrome vary greatly among individuals and may be mild to severe. Characteristics may be related to the specific gene containing the mutation.
Facial features
Facial appearance is just one of the major clinical characteristics that contribute to a diagnosis of Noonan syndrome. These attributes might be more pronounced in babies and young children but change with age. In adulthood, these different features are subtle.
Characteristics may include the following:
- Eyes are wide-set and down-slanting with droopy lids. Irises are pale blue or green.
- Ears are low-set and rotated backward.
- Nose is depressed at the top, with a wide base and bulbous tip.
- The mouth has a deep groove between the nose and the mouth and wide peaks in the upper lip. The crease that runs from the edge of the nose to the corner of the mouth becomes deeply grooved with age. Teeth may be crooked, the inside roof of the mouth (palate) may be highly arched and the lower jaw may be small.
- Facial features may appear coarse, but appear sharper with age. The face may appear droopy and expressionless.
- Head may appear large with a prominent forehead and a low hairline on the back of the head.
- The skin may appear thin and transparent with age.
Heart disease
A lot of people with Noonan syndrome are born with some kind of heart defect (congenital heart disease), accounting for a number of the vital symptoms and signs of this disease. Some heart problems can happen later in life. Some forms of congenital heart disease associated with this disease include:
Valve disorders. Pulmonary valve stenosis is a narrowing of the pulmonary valve, the flap of tissue that divides the lower right chamber (ventricle) of the center in the artery which provides blood to the lungs (pulmonary artery). It is the most common heart disease seen with Noonan syndrome, and it can occur alone or together with other heart problems.
Irregular heart rhythm. This can occur with or without structural heart abnormalities. Irregular heart rhythm occurs in the majority of people with Noonan syndrome.
Growth issues
Noonan syndrome can affect normal growth. Many children with Noonan syndrome don’t grow at a normal rate. Issues may include the following:
- Growth hormone levels may be insufficient.
- The growth spurt that’s usually seen during the teenage years may be delayed. But because this disorder causes bone maturity to be delayed, growth sometimes continues into the late teens.
- By adulthood, some people with Noonan syndrome may have normal height, but short stature is more common.
- Birth weight will likely be normal, but growth slows over time.
- Eating difficulties may result in inadequate nutrition and poor weight gain.
Causes of noonan syndrome
Noonan syndrome is caused by genetic mutation. These mutations can happen in numerous genes. Defects in these genes trigger the creation of proteins which are constantly active. As these genes play a part in the creation of many tissues throughout the body, this continuous activation of proteins disrupts the normal process of cell growth and division.
The mutations that cause Noonan syndrome can be:
- Inherited. Children who have one parent with Noonan syndrome who carries the defective gene (autosomal dominant) have a 50 percent chance of developing the disorder.
- Random. Noonan can develop because of a new mutation in children who don’t have a genetic predisposition for the disorder (de novo).
Prevention
Since several cases of Noonan syndrome happen spontaneously, there is no known way to stop it. But in case you’ve got a family history of the syndrome, speak with your physician about the advantages of genetic counseling before you have kids. Noonan syndrome could also be detected with molecular genetic testing.
In case Noonan is discovered early, it is possible that continuing and detailed care may reduce some of its own complications, like heart disease.
