Every baby is born with uniqueness and different characteristics. But, what if your little one is born with a distinctive facial shape accompanied by other congenital abnormalities, such as Noonan syndrome. This condition was first described in 1883 by Jacqueline Noonan, an American pediatric cardiologist who described a further case in 1963.
It is known that until now there is no treatment forNoonan syndrome, but it is often possible to successfully manage many aspects of the condition. So what exactly is the syndrome? Can it be prevented?
Definition
Noonan syndrome is a genetic condition that can cause a variety of distinctive features and health problems. It is characterized by somewhat unusual facial features, short stature, heart defects, bleeding problems, bone malformations, and many other signs and symptoms.
Symptom
This condition is present before birth, although milder cases may not be diagnosed until the child is older.
The most common symptoms and characteristics of Noonan syndrome are:
Facial Features
Facial appearance is one of the main clinical features that lead to the diagnosis of Noonan syndrome. These features may be more prominent in infants and young children, but change with age. In adulthood, these distinct features become more subtle.
Features may include the following:
- The eyes are wide and slanted downwards with drooping eyelids. The iris is pale blue or green.
- The ears are set low and rotated back.
- The nose is pressed at the top, with a wide base and rounded tip.
- The mouth has a deep groove between the nose and mouth and a wide peak on the upper lip. The folds that run from the edge of the nose to the corners of the mouth become deeply indented with age. The teeth may be crooked, the inner roof of the mouth (palate) may be strongly arched and the lower jaw may be small.
- Facial features may appear coarse, but become sharper with age. The face may appear droopy and expressionless.
- The head may appear large with a prominent forehead and a low hairline at the back of the head.
- Skin may appear thin and translucent as we age.
Heart disease
Many people with this syndrome are born with some form of heart defect (congenital heart disease), which are some of the main signs and symptoms of the disorder. Some heart problems can develop later in life. Some forms of congenital heart disease associated with this disorder include:
- Valve disorder
- Thickening of the heart muscle (hypertrophic cardiomyopathy)
- Other structural heart defects
- Irregular heart rhythm
Growth Problems
Many children with this syndrome do not grow at a normal rate. Problems may include the following:
- Birth weight will likely be normal, but growth slows over time.
- Difficulty eating can lead to inadequate nutrition and poor weight gain.
- Growth hormone levels may be insufficient.
- The growth spurt that is usually seen during adolescence may be delayed. However, because the disorder causes delayed skeletal maturity, growth sometimes continues into late adolescence.
- In adulthood, some people with this condition may be of normal height, but short stature is more common.
Musculoskeletal Problems
- Some common problems may include:
- An unusual chest shape often with a sunken sternum (pectus excavatum) or a raised sternum (pectus carinatum)
- Wide nipples
- Short neck, often with extra folds of skin (webbed neck) or prominent neck muscles (trapezius)
- Spinal deformity
Cognitive Disability
Intelligence is not affected for most people with this disease. However, individuals may have:
- Increased risk of learning disabilities and mild intellectual disability
- A wide range of mental, emotional and behavioral problems that are usually mild
- Hearing and vision deficits that can make learning difficult.
Eye Conditions
Common signs of Noonan syndrome are abnormalities of the eyes and eyelids. These may include:
- Problems with the eye muscles, such as crossed eyes (strabismus)
- Refractive problems, such as astigmatism, nearsightedness (myopia) or farsightedness (hypermetropia)
- Rapid eye movement (nystagmus)
- Cataract
Hearing Problems
Noonan syndrome can cause hearing loss due to nerve problems or structural abnormalities in the bones of the inner ear. For example, excessive bleeding and bruising due to clotting defects or having too few platelets.
Lymphatic Conditions
Problems with the lymphatic system, which drains excess fluid from the body and helps fight infection, can be a symptom. These problems can appear before or after birth or develop in adolescence or adulthood. They can be focused in a particular area of the body or spread widely. They most often cause excess fluid (lymphedema) in the backs of the hands or the tops of the feet.
Affected infants may have feeding problems, which usually improve by age 1 or 2. Infants with Noonan syndrome may be born with swollen hands and feet caused by fluid buildup (lymphedema), which may resolve on its own. Older adults may also develop lymphedema, usually in the ankles and lower legs.
Genital and Kidney Conditions
Many people, especially men, with Noonan syndrome can have problems with their genitals and kidneys, such as:
- Undescended testicles (cryptorchidism) are common in men.
- Puberty can be delayed in both boys and girls.
- Most women develop normal fertility. However, in men, fertility may not develop normally, often due to undescended testicles.
- Kidney problems are usually mild and occur in a small number of people with this syndrome.
Skin Conditions
People with Noonan syndrome may have skin conditions, the most common of which are:
- Various problems that affect skin color and texture
- Curly, coarse hair or sparse hair.
Reason
According to the Mayo Clinic , Noonan syndrome is caused by genetic mutations. These mutations can be:
Descendants
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 syndrome can develop due to new mutations in children who do not have a genetic predisposition for the disorder ( de novo ).
Frequency of Occurrence
It is estimated that between 1 in 1,000 and 2,500 children are born with Noonan syndrome.
Risk Factors
A parent with Noonan syndrome has a 50 percent (one in two) chance of passing the defective gene to their child. A child who inherits the defective gene may have fewer or more symptoms than an affected parent.
Diagnosis
Noonan syndrome may be suspected if a child has several signs and symptoms associated with the condition. However, these symptoms can have a number of different causes, making it difficult to make a diagnosis based on them alone.
The National Health Service says, Parents may be referred to a genetics specialist for genetic testing. In most cases, Noonan syndrome can be confirmed with a blood test for a range of genetic mutations. However, in around 1 in 5 cases no specific mutation can be found, so a negative blood test will not rule out Noonan syndrome.
If Noonan syndrome is confirmed or strongly suspected, further testing is needed to determine the extent of the symptoms. These tests may include:
- electrocardiogram (ECG) to measure the electrical activity of the heart
- echocardiogram, ultrasound scan of the heart
- educational assessment
- blood test to check how well your blood clots
- eye test to check for problems such as squinting or blurred vision
- hearing test to check for problems such as hearing loss caused by a middle ear infection or damage to cells or nerves in the ear
Some of these tests may need to be repeated regularly after diagnosis, to monitor symptoms.
Additionally, Noonan syndrome can be tested during pregnancy. If you are pregnant, your unborn baby can be tested for Noonan syndrome if you, your partner or a close family member are found to carry one of the faulty genes associated with the condition. Routine ultrasound scans detect possible signs of the condition in your baby, such as polyhydramnios (excessive amniotic fluid), pleural effusion (fluid in the space around the lungs) or fluid buildup in certain other parts of the body. Testing for Noonan syndrome during pregnancy involves collecting a sample of your baby’s DNA and checking it for any faulty genes associated with the condition.
During pregnancy, this test can be done using chorionic villus sampling (where a sample of cells is removed from the placenta) or amniocentesis (where a sample of amniotic fluid is removed). Both of these tests have a 0.5 to 1% chance of causing miscarriage. If your baby is found to have one of the faulty genes, a genetic counselor will talk to you about what the test results mean and what your options are.
Complications
Some people with Noonan syndrome develop cancer, particularly those involving the blood-forming cells (leukemia). It is estimated that children with Noonan syndrome have an eight-fold increased risk of developing leukemia or other cancers compared to their peers.
Other complications may arise that may require special attention, including:
- Developmental delay
- Bleeding and bruising
- Lymphatic complications
- Urinary tract complications
- Fertility problems.
Handling
While there is no way to correct the gene changes that cause Noonan syndrome, treatments can help minimize its effects. Treatment of symptoms and complications depends on the type and severity of the condition. Many of the health and physical problems associated with the syndrome are treated as they would be for anyone with similar health problems. However, taken together, many of the disorders require a coordinated team approach.
Suggested approaches may include:
- Heart care
- Treating low growth rates
- Overcoming learning disabilities
- Vision and hearing care
- Treatment for bleeding and bruising
- Treatment for lymphatic problems
- Treatment for genital problems
Other evaluations and regular follow-up care may be recommended depending on the specific problem, such as regular dental care. Children, adolescents, and adults should continue to have ongoing periodic evaluations by a health care professional.
Prevention
Because some cases of Noonan syndrome occur spontaneously, there is no known way to prevent it. However, if you have a family history of the syndrome, talk to your doctor about the benefits of genetic counseling before having children. If the syndrome is detected early, it is possible that ongoing, comprehensive treatment can reduce some of its complications, such as heart disease.
Hopefully the information regarding Noonan syndrome is useful!
Republished with permission from theAsianparent Indonesia
