This is a genetic disorder in which the normal development of different body parts is stopped. It is called Noonan syndrome and it usually impacts people in different ways such as through unusual facial features, short height, problems with the heart, and others. This syndrome also reduces the development of children (including talking, walking, and learning new things).
The primary cause of this condition is a gene mutation inherited from one parent (dominant inheritance). However, this syndrome can happen spontaneously where there is no family history of Noonan syndrome.
Although there is no cure for this genetic disorder, doctors may recommend some medicines and hormones to lessen the symptoms. For instance, they can prescribe a growth hormone to treat short height.
Symptoms
The symptoms caused by this genetic disease vary among patients from mild to severe. Check below some examples:
Facial Features
Unusual facial features are one of the primary symptoms of Noonan syndrome. However, facial features are seen well during childhood because with aging they change and become less clear in adulthood. Check below some features caused by Noonan syndrome:
- Ears – In people with this syndrome ears are usually set low and look like they are tipped backward.
- Nose – It appears depressed at the top with a wide base and round tip.
- Mouth – This syndrome provokes the mouth to appear with a deep groove between the mouth and nose and wide peaks in the upper lip. Moreover, the lower jaw may be small, and teeth crooked.
- Eyes – They are set wide, have droopy lids, and may be pale blue or green.
- Facial features – Those who suffer from Noonan syndrome cannot show expressions. Furthermore, the face may look sharper with age.
- Head – is usually larger, with a big forehead and a low hairline in the head’s back.
- Skin usually becomes transparent with aging.
Heart Problems
Many people with this syndrome have heart problems at birth (congenital heart condition). Sometimes, doctors diagnose this condition according to heart problems present at birth. However, heart problems can happen later in life. Check below some congenital heart disease types associated with Noonan syndrome:
- Valve conditions – One of them is pulmonary valve stenosis. This is a heart condition in which the narrowing of the pulmonary valve happens. This valve comes from the artery that supplies the lungs with blood (pulmonary artery). This heart condition is one of the most common heart diseases noticed in people with Noonan syndrome. In addition, pulmonary valve stenosis can occur alone or with other heart problems.
- Hypertrophic cardiomyopathy – This is a condition in which an abnormal growth or thickening of the heart muscle happens. It can negatively affect some people with this syndrome.
- Other heart conditions – Another heart problem is a ventricular septal defect (in which heart structure problems occur). Sometimes, people with Noonan syndrome experience narrowing of the pulmonary artery or other major blood vessels (called aorta).
- Irregular heart rhythm – This can happen with or without heart structure problems. Moreover, most people with this syndrome have irregular heart rhythms.
Growth Problems
This genetic disorder frequently impacts growth and many children do not grow at a normal rate. Check below some growth problems caused by Noonan syndrome:
- Difficulty eating which can lead to poor nutrition and weight gain
- Reduced growth hormone levels
- Normal weight at birth but over time the child will grow slower
- Short height as an adult and it happens commonly but some adults with this syndrome may be not short
Muscles and Bones Problems
Check below some common problems caused by this genetic condition:
- Nipples are wide apart
- Short neck (commonly along with folds on the skin)
- The spine has an abnormal curve
- Pectus excavatum (a health condition in which ribs sink and the breastbone is too far into the chest). Sometimes, people with Noonan syndrome experience pectus carinatum (in which the breastbone and ribs grow outward)
Learning Disabilities
Commonly, Noonan syndrome does not impact people’s intelligence but some of them may experience the following problems. Examples include:
- Wide range of mental, emotional, and behavioral problems (often mild)
- Vision and hearing problems
- Increased risk of learning disabilities and mild intellectual disability
Eye Diseases
Abnormal eyes and eyelids are the primary symptoms of Noonan syndrome but some people may also experience:
- Eye muscle problems (including strabismus also known as cross-eye)
- Nystagmus (fast eyeballs movement)
- Cataracts (cloudy eye)
- In some cases, people with this syndrome can experience refractive problems, which means the lens or cornea is egg-shaped with curves that do not match. As a result, it may provoke distorted or blurry vision. In such cases, people also cannot see things that are too close or too far.
Hearing Issues
This genetic disorder can cause problems with hearing due to nerve problems or an abnormal inner ear bone structure.
Bleeding Problems
Easy bruising and bleeding are common in people with Noonan syndrome. It occurs because blood is not clotting properly due to the low protein levels required to make clots. As a result, they can bleed more than usual.
Lymphatic Diseases
Lymphatic system problems often happen in people with Noonan syndrome. It drains the extra fluid from the body to help fight against infections. However, problems with the lymphatic system may lead to the following problems. For example:
- Sometimes, children are born with swelling of the neck tissues, hands, and feet.
- Excess fluid in the back of the hands or top of the feet (lymphedema).
- Appears on a specific body part or may be widespread.
Genital Diseases
These include:
- Testicles – it is very common for men to have undescended testicles. It means that the testes haven’t moved into the proper position (in the scrotum).
- Puberty – Delayed puberty occurs in both men and women.
- Fertility – Most women with this syndrome usually do not experience fertility problems but men can notice problems with fertility due to undescended testes.
Skin Diseases
People with this genetic condition may experience skin disorders that affect the color and texture of the skin. Furthermore, they can have sparse or coarse hair.
If you suspect your children have this genetic disorder or he/she experienced any of the previous health problems, you should visit a doctor immediately.
Causes
The main cause of Noonan syndrome is a mutation in one or more genes. Genes produce certain proteins that play a vital role in how tissues form in the body and constant production of proteins from abnormal genes interrupts normal cell growth and division. Gene mutations that provoke this syndrome can be:
- Random – It means that gene changes occur spontaneously and the child does not get it from biological parents. In such cases, the disease is called a de novo genetic condition.
- Inherited – If even one biological parent carries this mutated gene, biological children have 50% of getting this syndrome. Thus, it is called an autosomal dominant inheritance pattern.
Despite previous ways in which people get Noonan syndrome, sometimes, determining the cause of this genetic disorder is not possible.
What Are The Potential Complications of Noonan Syndrome?
People with Noonan syndrome may experience the following complications. If any of them occur, immediately inform your healthcare professional. For example:
- Developmental delays – Usually, people with this genetic disorder grow slower than other children without this condition.
- Bruising and bleeding – These symptoms occur commonly in people with this syndrome but they are identified often during dental work or surgery.
- Fluid buildup – This health problem is called lymphedema and means that an increased amount of fluid builds up in the body.
- Urinary tract problems – A change in kidney structure may elevate your risk of getting urinary tract infections.
- Fertility problems – Low sperm count in males and other fertility problems can occur due to Noonan syndrome.
- Increased risk of cancer – People with this genetic condition are at higher risk of developing leukemia and other tumor types.
Additionally, it is not possible to prevent this genetic condition. However, if the mutated gene is detected early, you can reduce the risk of heart disease with proper care.
Diagnosis
Diagnosing this condition is difficult because it is hard to find features associated with this syndrome. Sometimes, this disease is not found until adulthood. The only test that can confirm the condition is genetic testing.
Treatment
While there is no way to cure the condition, doctors will recommend treatments to lessen the symptoms and prevent complications. However, treatments for people with Noonan syndrome are different because depends on the severity of the condition, other existing health problems, and other factors. Check below some common treatments prescribed by doctors for people with this genetic disorder:
- Heart treatment – Most people with Noonan syndrome experience heart problems, so physicians will prescribe treatment to resolve problems with the heart. These include surgery, medicines, and other procedures.
- Low growth rate treatment – If you notice that your child has delayed growth and development, doctors may prescribe human growth hormone which usually is effective against this problem.
- Hearing and vision treatments – For people with this genetic disorder, eye examinations are advised every 2 years. In most cases, glasses are enough to treat eye problems. However, surgery may be recommended in some cases (such as cataracts).
- Bleeding and bruising treatment – It is not allowed to use Aspirin or products that contain it if you have a history of bruising and bleeding issues. Inform your healthcare professional about bruising and bleeding problems before any procedure.
- Fluid buildup treatment – Doctors may prescribe some medicines and procedures to remove extra fluid from the body.
- Genital conditions treatment – In case your child experiences undescended testes, surgery is the only way to treat this problem.
Frequently Asked Questions
What is the life expectancy in people with Noonan syndrome?
The life expectancy is normal if there are no heart problems. However, if there are serious heart problems, life expectancy decreases significantly. Unfortunately, approximately 50% of people with Noonan syndrome have congenital heart defects.
Does Noonan syndrome affect the brain?
Yes, some studies showed that people with Noonan syndrome have a deficit in specific neuropsychological domains (including learning and memory).
What are common problems in people with Noonan syndrome?
These include mood disturbances, communication problems, attention-deficit/hyperactivity disorder, and difficulties with social interactions. Ask your healthcare professional if you have additional questions.
