Noonan Syndrome

Noonan Syndrome: Causes, Picture, Symptoms and Treatment

Noonan syndrome refers to the genetic disorder affecting children. It prevents the normal growth and development of the person. The condition affects various parts of the body. A person can suffer from diverse problems due to the syndrome. It can affect a person’s life in many ways. From developing abnormal facial characteristics, heart problems, learning disabilities, developmental delays to other physical problems, it affects people in different ways. Severe cases of mutation can affect one in thousand to two thousand births. While mild cases are more common as it affects one in a hundred births. You have no specific treatment available to cure the condition completely. The treatment options available aims to manage the problems triggered by the syndrome.

Gene mutation acquired by birth from parents with the defective gene or due to spontaneous mutation can cause mild to severe deformities. The syndrome is characterized by variable expressivity. So, parents of a child with mild cases tend to ignore the symptoms. The lack of glaring problems causes it to go undetected for several years. But, others may face severe complications due to the syndrome. It is possible to manage the symptoms triggered due to the disorder with early medical intervention. With effective treatment options available, children with the syndrome can improve their quality of life.

Symptoms Of Noonan Syndrome

The signs and symptoms associated with Noonan syndrome vary depending on the severity. In most cases, the characteristics depend on the specific gene that contains the mutation. You can observe the following signs in people affected by the syndrome:

Facial Features

Noonan Syndrome

Distinctive facial appearance is one of the key clinical features. It helps in the conclusive diagnosis of the syndrome. The symptoms appear more pronounces in infants as well as young children. But, as the age ages, the features may change. As the person reaches adulthood, the features tend to become more subtle. So, the affected child may show the following characteristics:

  • Wide-set eye with droopy lids (ptosis)
  • Large head with a wide forehead
  • Pale Irises (pale blue or green)
  • Low-set ears that are rotated backward
  • A short and broad nose (depressed at the top with a wide base and rounded tip)
  • The deep groove between the mouth and nose
  • Crooked teeth
  • Palate (roof of the mouth) is highly arched
  • Small jaw
  • A wide peak in the upper lip
  • Low hairline on the back of the head
  • Drooping face with lack of expression

As the affected person ages, the facial features tend to appear sharper. So, the distinctive nature of the syndrome starts to fade away. But, the face still appears expressionless. The skin also tends to appear thin, which almost look transparent with advanced age.

Heart Problems

Most of the people born with genetic disorders suffer from congenital heart disease (heart defects by birth). It is one of the prominent signs linked to the disorder. In some cases, the condition may develop later in life. The different forms of congenital heart disease associated with the syndrome include:

Valve Disorders

Valve Disorders

Pulmonary valve stenosis is one of the common issues linked to the syndrome. The condition causes the narrowing of the pulmonary valve. The pulmonary valve is the tissue flap separating the ventricle (lower right chamber of the heart) from the pulmonary artery (the artery supplying blood to the lungs). It occurs alone or along with other heart defects.

Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy

It causes thickening of the heart muscles. The abnormal thickening or growth of the heart muscles can put a strain on the heart.

Septal Defect

Affected people can develop a hole in the wall of the heart. It mostly develops on the wall separating the lower chambers of the heart. The condition is referred to as a ventricular septal defect. The small hole may not cause any symptoms. But, larger ones can make the heart and lungs work harder, triggering several symptoms.

Pulmonary Artery Stenosis

Pulmonary Artery Stenosis

The condition can cause narrowing of the artery carrying blood to the lungs for oxygen. The condition is known medically as pulmonary artery stenosis.

Aortic Coarctation

Aortic Coarctation

The condition causes the narrowing of the aorta. It leads to the left ventricle work harder to pump blood. It usually occurs with other heart defects.

Irregular Heart Rhythm

The problem can develop with/without structural heart abnormalities. People affected by the syndrome have abnormal heart rhythm.

Growth Issues

The genetic disorder has an adverse effect on the growth of the affected person. Many children suffering from syndrome fail to grow at a normal rate. So, the genetic disorder can trigger the following:

  • Normal birth weight, which slows as time passes
  • Problems with eating properly, causing malnutrition and poor weight gain
  • Insufficient levels of growth hormone
  • Delayed growth spurt in teenage years
  • Continued growth in the late teen years
  • Delayed bone maturity
  • Short stature (but some people may have normal height by the time they reach adulthood)

Musculoskeletal Issues

The syndrome affects triggers musculoskeletal issues in affected children. So, you can see the following signs:

  • Chest with an unusual shape mostly with a raised sternum (pectus carinatum) or sunken sternum (pectus excavatum)
  • Deformities of spine
  • Wide-set nipples
  • Webbed neck (excess folds of skin), Trapezius (prominent neck muscles) or short neck

Learning Disabilities

While the syndrome does not affect the intelligence of the affected people, it can cause learning problems. The issues faced by a child suffering from the syndrome are:

  • Mild intellectual disability
  • Increased chances of learning disabilities
  • Wide range of behavioral, emotional, and mental issues mild in nature
  • Problems with learning due to hearing and vision problems

Eye Conditions

Eye abnormalities are a common sign in people affected by Noonan Syndrome. The problem can cause eye and eyelids abnormalities. The issues include:

  • Problems with eye muscles, triggering issues like strabismus (cross-eye)
  • Refractive issues like farsightedness (hyperopia), nearsightedness (myopia), or astigmatism
  • Cataracts
  • Nystagmus (rapid movement of the eyeballs)

Hearing Problems

The genetic disorder can cause structural abnormalities in the inner ear bones. It can also cause nerve issues in the ear. So, the disorder can lead to hearing problems.


The condition can cause clotting defects, leading to excess bleeding as well as bruising. The affected also tend to have few blood platelets.

Lymphatic Conditions

The genetic disorder causes issues with the lymphatic system. It aids in draining the excess fluid from your body. The lymphatic system also helps fight infections. But, the disorder can trigger the following:

  • Problems occur before or after the birth of the child with the syndrome
  • Issues can also develop in teenage years or adulthood
  • Suffer from problems in specific area or widespread issues
  • Cause excess fluid accumulation (lymphedema) on top of the feet or back of the hands

Genital And Kidney Conditions

The syndrome can trigger kidney and genital problems, especially in men suffering from the syndrome. Therefore, you can see the following signs:

  • Undescended testicles are common among male child suffering from the syndrome
  • Both boys and girls experience delayed puberty due to the syndrome
  • The condition can cause a female to develop normal fertility. But, men experience infertility due to decreased sperm count. It happens due to the undescended testicles.
  • Mild kidney problems are fairly common among affected people

Skin Conditions

The genetic disorder can trigger different skin condition. Most of the people affected by the syndrome can experience:

  • Problems affecting the texture and color of the skin
  • Coarse, curly hair/sparse hair

In most cases, the signs associated with the syndrome appear mild or subtle. But, if you suspect your child suffers from the syndrome, then see a pediatrician immediately. Parents with defective genes have more chances of passing it to their children. So, it is important for such parents to see a specialist to detect the issue in their children. A physician or pediatrician refers the child to a geneticist or cardiologist for further evaluation. If you have a family history of the disease, then it is wise to undergo prenatal tests to detect the problem.

Causes Of Noonan Syndrome

Genetic mutation is the main cause of Noonan syndrome. The mutation tends to occur in multiple genes. The defective genes cause enhanced production of continually active proteins. The constant activation of protein can disrupt the normal process of cell growth as well as cell division. It is because the affected genes play an important role in tissue formation throughout the body. A person is affected by the gene mutation in two methods:


Some of the children suffer from the syndrome due to one of the parents carrying the defective gene). The autosomal dominant inheritance pattern increases your chance of developing the disorder by 50%.


You can develop the gene mutation randomly. Some children suffer from the disorder due to a new mutation. Their parents have no defective gene. Such cases have no genetic predisposition of the disorder (de novo).

Risk Factors Associated With Noonan Syndrome

It is not a common disorder that affects everyone. The chances of the syndrome increase if you have one parent with Noonan syndrome. A parent with the syndrome has a 50% chance of passing the defective genes to their child. The child inheriting the gene defect can suffer from fewer or more symptoms compared to the affected parent.

Complications Due To Noonan Syndrome

If a child suffers from Noonan syndrome, then they suffer from several complications. Special attention is required as a child can expect the following:

Developmental Delays

A child suffering from the syndrome can suffer developmentally. So, they find it difficult to organize and have a spatial sense. At times, the developmental challenges faced by the child need a special plan to address them. So, you need to get special care for educational and learning needs.

Bruising And Bleeding

Some people may not learn about the problem until they undergo dental or invasive procedures. It can lead to excessive bruising and bleeding. It is a common complication associated with the syndrome.

Lymphatic Complications

The complication can lead to excess fluid getting stored in various parts of the body. In some cases, fluid tends to collect in areas like the lungs and heart.

Urinary Tract Complications

Children or adults suffering from the syndrome can experience structural abnormalities of the kidneys. So, it increases the risk of problems like urinary tract infection.

Fertility Issues

Men suffering from the syndrome can suffer from infertility. They tend to have low sperm count as well as other fertility issues. It is because of the malfunctioning of the testicles or undescended testicles.

Cancer Risk

The syndrome can increase the risk of developing cancer. So, affected people can develop certain types of cancers (like leukemia) or tumors.

Diagnosis Of Noonan Syndrome

The signs associated with Noonan syndrome are hard to identify. You need professional assistance to detect some key signs indicating the problem. The subtlety of the issue makes it a complicated problem to detect. In some cases, the condition is not diagnosed until the affected person reaches adulthood or after having a child with pronounced symptoms of the syndrome. In such cases, the doctor can perform the following diagnostic tests to confirm the issue.

Molecular Genetic Testing

To confirm the diagnosis, the doctor can suggest molecular genetic testing. The tests, also known as gene tests, study short lengths of DNA or single genes. It helps identify the mutations or variations triggering the genetic disorder.

Detect Heart Problems

The affected people can suffer from heart problems. So, the physician can refer the person to a specialist like a cardiologist to unearth the evidence of heart problems. The specialist doctor can assess the type as well as the severity of the heart problem.

Treatment For Noonan Syndrome

You need to remember that no treatment can reverse genetic disorders. You have no medications or therapy available to repair gene chances. But, the treatment can help minimize the effects. With early diagnosis, you get medical assistance to control the problems better. So, try to get medical help as early as possible for greater benefits. The treatment of the different symptoms associated with the syndrome depends on the type and severity of the syndrome. Different problems arising due to the syndrome require a coordinated team approach to manage it effectively. The treatment for health, as well as physical issues associated with the condition, are treated like similar health issues. The recommended approaches include:

Heart Treatment

Heart problems affect people suffering from the syndrome. So, the specialist doctor prescribes drugs to treat the issues. If the problem is associated with heart valves, then it requires heart surgery. The condition requires periodic evaluation of heart function. Therefore, you need to make an appointment for an evaluation.

Treating Low Growth Rate

Children suffering from the condition need to measure their height at least three times a year until they reach three years of age. Then, it is essential to measure the height once every year until the affected person reaches adulthood. It is to ensure he/she is growing. The doctor also evaluates nutrition by suggesting blood tests. If the child has insufficient growth hormone, then the doctor prescribes a growth hormone to address the problem.

Managing Learning Disabilities

Children can suffer from developmental problems due to the genetic condition. So, you need to talk to a doctor about the different stimulation programs available. Therapies can beneficial for addressing a variety of problems. Physical and speech therapies are beneficial for affected children. To deal with learning problems, you need to arrange special education as well as personalized teaching strategies.

Hearing And Vision Treatments

Hearing screening is required for the affected persons to detect any issues. It is a necessity to find any hearing problems during childhood. Children suffering from the genetic disorder can experience eye problems. So, eye exams are recommended at least every two years. The common eye issues associated with the syndrome are treated with glasses alone. In cases like cataracts, the affected individuals need to undergo surgery.

Treatment For Bleeding And Bruising

The genetic disorder makes a person vulnerable to bleeding and bruising. So, the doctor suggests avoiding aspirin and aspirin-containing medications. The doctor can prescribe medications that prevent blood clotting. It is important to notify the doctor before undergoing any procedure to avoid complications.

Treatment For Lymphatic Problems

The lymphatic problem can affect children in many ways. It may not require any treatment. In case, the problem requires treatment, then the doctor can suggest appropriate measures to handle it.

Treatment For Genital Problems

Undescended testicles may move to the proper position within the first few months. Boys who still suffer any genital issues after a few months require invasive surgery to move the position to one or both testicles.

Other Treatments

Other evaluation and treatment are necessary for the specific problem the child suffers due to the genetic problem. So, regular evaluation and follow-up care us recommended to deal with the issues. The affected person needs constant or periodic evaluation by the healthcare professional.

Coping And Support For Noonan Syndrome

The caretakers who oversee the necessities of the affected individual need support for coping with the stress and emotional upheaval associated with it. So, you need to gather necessary information about the problem from trustworthy resources available online. You need to talk to your doctor about finding local support groups or parents dealing with similar syndrome. Support groups are also available online to get the necessary guidance and help deal with the syndrome.

Preventing Noonan Syndrome

The condition occurs spontaneously. Therefore, there is no known method to prevent the condition. But, if you have a family history of the genetic disorder, you need to consult a doctor. You need to consider undergoing genetic counseling before planning to have children. The condition is detected with molecular genetic testing. So, you can know the probability of having children with the same syndrome. It can help you make a decision.
If you see signs of the syndrome in a child, then get medical help. With early diagnosis, you can avoid some of the health complications like heart problems associated with the disorder. The ongoing and comprehensive medical care can reduce the negative effects associated with the syndrome.


The severity and prognosis of Noonan syndrome depend on the individual person suffering from it. Some may have only mild symptoms while others can suffer severe heart problems. But, detecting the condition early and getting treatment can help prevent further complications. So, if you suspect the condition, get a conclusive diagnosis from a specialist doctor. With medical management, you can improve the affected person’s quality of life.

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