Home Syndrome What is Noonan Syndrome?

What is Noonan Syndrome?

Noonan Syndrome

Noonan syndrome is a genetic problem. In which the body parts do not develop normally. A person can be affected by Noonan syndrome in many ways. A person with Noonan syndrome may have an abnormal face, short stature, heart defects, and other physical problems. Along with this, physical development is also delayed.

Noonan Syndrome is caused by a genetic mutation. It is acquired when a child inherits the affected gene from a parent. It can also occur as a spontaneous mutation. This means that there is no family history involved.

Management of Noonan syndrome focuses on controlling the symptoms and complications of the disorder. Growth hormone may be used to treat short stature in some people with Noonan syndrome.

How Common Is Noonan Syndrome

Noonan syndrome occurs in about 1 in 1000 to 2500 people. Contact your doctor for more details.

Decoding The Genetics Of Noonan Syndrome

Delves into the genetic causes of Noonan Syndrome and the specific genetic mutations that can lead to its development. Noonan Syndrome is caused by a genetic mutation, it can be inherited from a parent, or it can occur as a spontaneous mutation. The disorder is caused by a mutation in one of several genes that are involved in the normal development of the heart and other body parts.

The most common genetic cause of Noonan Syndrome is a mutation in the PTPN11 gene. This gene provides instructions for making a protein that helps regulate cell growth and division. Other genes that have been linked to Noonan Syndrome include KRAS, SOS1, RAF1, and RIT1. These genes are involved in signaling pathways that regulate cell growth and development.

Mutations in these genes can lead to abnormal development of the heart and other body parts, resulting in the symptoms of Noonan Syndrome. It is important to note that the specific genetic mutation can influence the severity and type of symptoms that a person with Noonan Syndrome may experience. Understanding the genetic basis of the disorder can help with diagnosis and management, as well as pave the way for future research into potential therapies.


Mild Noonan Syndrome

Exploring the Milder Side of Noonan Syndrome refers to cases of the disorder that may present with less obvious or less severe symptoms. These milder cases of Noonan Syndrome can be missed or misdiagnosed, making it important for doctors and healthcare professionals to be aware of the disorder and its subtle symptoms.

In mild cases of Noonan Syndrome, individuals may have fewer facial abnormalities, less pronounced short stature, and milder heart defects. They may also have fewer developmental delays and cognitive impairments. These individuals may also have fewer bleeding episodes or may not have any bleeding disorders at all.

However, it is important to note that even mild cases of Noonan Syndrome can still have a significant impact on an individual’s quality of life. They may still have difficulty with social interactions and may have low self-esteem due to their physical appearance. They may also have difficulty with activities of daily living and may require assistance with certain tasks.

It is also important to note that mild cases of Noonan Syndrome are still at risk for heart defects and may require close monitoring and management to prevent complications.

Overall, it is important to recognize and manage mild cases of Noonan Syndrome to improve the quality of life for those affected by the disorder. This includes providing support and guidance for psychological and social well-being, as well as close monitoring and management of heart defects to prevent complications.

Symptoms of Noonan Syndrome?

The symptoms of Noonan syndrome can vary from person to person.  These symptoms may be related to the specific gene in which the mutation occurs. Facial appearance is one of the clinical features used to diagnose Noonan syndrome. These features may be more pronounced in infants and young children, but change with age. These characteristics become more subtle as they grow older.

Common Symptoms Of Noonan Syndrome Are:

  • Facial Abnormality
  • Short Stature
  • Congenital Heart Defect
  • Wide Or Crooked Neck
  • Skin can appear thin and translucent with age
  • Eye Problems Such As Squint
  • Ears Folded Back
  • Facial Features May Appear Coarse
  • Have Bleeding Problems
  • Abnormal chest size
  • Slowing Of Physical Development
  • The head may appear larger with less hairline on the forehead and back of the head
  • Undescended Testes In Males

Short Height

Typically, newborns with Noonan syndrome are of average length. At around age 2, you could notice that they don’t develop as swiftly as other kids their age.

The projected growth spurt that often occurs during puberty is either decreased or doesn’t happen at all, and puberty (when a child starts to mature physically and sexually) usually occurs a few years later than usual.

Human growth hormone medication has occasionally been reported to assist kids in growing to a more typical height. In men with Noonan syndrome, the average adult height is 162.5 cm (5 ft 3 in), whereas in women, it is 153 cm (5ft).

Other Characteristics

The Following Less Frequent Noonan Syndrome Symptoms Are Possible:

  • Learning Impairment: Noonan syndrome children typically have IQs that are somewhat below average, and a small percentage also have learning disabilities, but these are frequently mild.
  • Feeding Issues: infants with Noonan syndrome may struggle to swallow and chew food, and they may vomit right away after eating.
  • Behavior issues: Some children with Noonan syndrome may be picky eaters, behave immaturely in comparison to children their own age, struggle with attention, or have trouble identifying or expressing their own feelings or those of others.
  • Accelerated Bleeding Or Bruising: Children with Noonan syndrome may be more prone to bruising and severe bleeding from cuts or medical procedures because their blood may not always clot properly.
  • Ocular Disorders: including astigmatism, a lazy eye in which one eye has difficulty focusing, and a squint, where the eyes point in separate directions (slightly blurred vision caused by the front of the eye being an irregular shape)
  • Hypotonia: reduced muscle tone, which can delay your child’s achievement of certain early developmental milestones.
  • Inaccessible Testicles: One or both testicles may fail to drop into the scrotum in boys with Noonan syndrome (sac of skin that holds the testicles)
  • Fertility Issues: Boys with Noonan syndrome run the risk of having lower fertility, especially if undescended testicles aren’t removed at a young age. Girls’ fertility is typically unaffected.
  • Lymphedema: fluid accumulation in the lymphatic system (a network of vessels and glands distributed throughout the body)
  • Bone Marrow Issues: A tiny percentage of people can experience an aberrant white blood cell count, which occasionally resolves on its own but can also progress into leukemia.
  • Kidney Issues: such as having only one kidney

Leopard Disorder

The Subtype Of Noonan Syndrome Known As Leopard Syndrome Is Characterised By A Distinctive Pattern Of Persistent Symptoms.

Which are:

  • Dark brown to black skin patches
  • Heart problems
  • A greater gap between the eyes than typical (ocular hypertelorism)
  • Respiratory stenosis
  • Issues with the genitalia’s growth, like undescended
  • Testicles
  • Short stature
  • Loss of hearing

Features of Noonan Syndrome

Highlights the specific characteristics of Noonan Syndrome that can be used to diagnose the disorder. These features include facial abnormalities, short stature, and heart defects. Facial abnormalities in Noonan Syndrome can include a broad or webbed neck, low-set ears, and a small jaw. These features may be more pronounced in infants and young children, but they may change with age. Short stature is also a common feature of Noonan Syndrome, with affected individuals often being shorter than their peers.

Heart defects are also a common feature of Noonan Syndrome, with many individuals being born with some form of heart defect. The most common heart problem associated with Noonan Syndrome is Pulmonary valve stenosis, in which the flap of tissue that separates the lower right chamber of the heart from the artery that supplies blood to the lungs becomes narrow. Other heart defects that can occur in Noonan Syndrome include thickening of the heart muscle, irregular heart rhythm, and other structural defects of the heart.

It is important to note that symptoms of Noonan Syndrome can vary from person to person, and that not all individuals with the disorder will have all of these features. However, by identifying and understanding these unique features, doctors and healthcare professionals can improve the diagnosis and management of Noonan Syndrome for affected individuals and families.

Many people with Noonan syndrome are born with some form of heart defect, which accounts for some of the significant symptoms of the disorder. Heart related problems can happen later in the life of these people.

Some forms of congenital heart disease associated with this disorder include:

Valve Disorder

Pulmonary valve stenosis is the most common heart problem seen with Noonan syndrome.  It may occur alone or with other heart defects. In this, the flap of tissue that separates the lower right chamber of the heart from the artery that supplies blood to the lungs becomes narrow.

Thickening Of The Heart Muscle

This is the abnormal development, or thickening, of the heart muscle that affects some people with Noonan syndrome.

Irregular Heart Rhythm

It may occur with or without structural heart abnormalities.  Most people with Noonan syndrome have problems with irregular heart rhythms.

Other Structural Defects Of The Heart

A hole in the heart wall, separation of the heart’s two lower chambers, narrowing of the arteries that carry blood to the lungs for oxygen, or narrowing of a major blood vessel that carries blood from the heart to the body Does etc. problem is seen with Noonan syndrome.

Developmental Problems From Noonan Syndrome

Noonan syndrome can affect the growth of the body. Many children born with Noonan syndrome do not develop normally.

The following problems are seen in these:

  • Birth weight may be normal, but growth may slow down over time.
  • Difficulties in eating and drinking can lead to inadequate nutrition and poor weight gain.
  • Growth hormone levels may be insufficient.
  • There may be a delay in growth that usually occurs during adolescence. Due to this disorder, there is a delay in the maturation of the bones.
  • Noonan syndrome can cause hearing loss due to nerve problems or structural abnormalities in the bones of the inner ear.
  • Low platelets due to Noonan syndrome can cause excessive bleeding and bruising.
  • This can cause problems in the lymphatic system.

Apart from this, talk to your doctor to know more about the symptoms of Noonan syndrome.

When should I see a doctor?

If you are experiencing the symptoms mentioned above, see a doctor.  Also, do ask the doctor any kind of question or dilemma related to Noonan syndrome. Because everyone’s body reacts differently to Noonan Syndrome.

Reason of Noonan Syndrome

Cause of Noonan Syndrome

Noonan syndrome is caused by a genetic mutation. Several genes are responsible for this mutation. These genes make proteins that are constantly active. Because, these genes play a special role in building many tissues throughout the body. This activation of protein inhibits the process of cell growth and division.

Mutations In Noonan Syndrome Can Be Due To

Parents who have Noonan syndrome have a 50 percent chance that their children will also have Noonan syndrome.

Noonan Syndrome genetic mutation can also occur in children who do not have any genetic disorder.

Risk of Noonan Syndrome

What Is The Risk Of Noonan Syndrome?

The highest risk of developing Noonan syndrome is in those whose parents have genes related to this syndrome. On the other hand, if both parents have Noonan Syndrome, then one out of two children will be born suffering from this syndrome.


Do not consider the information provided here as any medical advice.  Always consult your doctor for more details.

How is Noonan Syndrome diagnosed?

Doctors look for symptoms to diagnose Noonan syndrome, but the symptoms of Noonan syndrome are often difficult to understand.  Sometimes the symptoms of Noonan syndrome don’t appear until adulthood. On the other hand, if the symptoms are visible since childhood, then that person appears to be suffering from the symptoms even when he grows up.  Apart from this, Noonan syndrome can be detected with the help of molecular genetic testing.  Also, if you have heart related problems, see a cardiologist.  He can understand your problem very well.

How is Noonan Syndrome treated?

The genes that cause Noonan syndrome cannot be repaired. With treatment, Noonan syndrome can lead a normal life. Treatment of Noonan syndrome depends on its symptoms. Because if you have other health problems then there may be difficulties in treating with it.

You can take treatment in the following ways

Heart treatment: If you develop a heart problem due to Noonan syndrome, you should get it treated. If there is a problem with the heart valves, surgery may be required.

Treatment of slow growth of the body: Measure the height of the child usually once till the age of three years.  Keep measuring the length from time to time till it grows.  Along with this, give proper nutrition so that the height of the child can be increased.  If your child has low levels of growth hormone, then growth hormone therapy is given along with some tests.

Know about learning disabilities: If your child is not showing interest in learning as he gets older, see your doctor.  The doctor will give physical and speech therapy etc. to the child.  Along with this, the child will start learning some things from the process of teaching.

Treatment for sight and hearing: The doctor examines the child’s eyes and ears. If there is a problem in this, treatment starts from childhood itself.  Apart from this, you must get the child’s eyes and ears checked at the age of two years.

Bleeding treatment: If the child has a bleeding problem, don’t give him blood thinners.  For this, the doctor will give blood clotting medicine.

Treatment of genitals: If the affected person’s testes are not in place, then they are kept in the scrotum by surgery.

Apart from this, a person suffering from Noonan syndrome usually needs a checkup.  For example, regular dental care.

How likely is it that another child will be born with the syndrome?

Talk to your GP about seeking a referral to a genetic counsellor if you have a kid with Noonan syndrome and neither you nor your partner have received a diagnosis for it.

To determine if one of you carries one of the defective genes linked to the illness, you may be able to undergo a genetic blood test.

The likelihood of producing a second child with the disorder is extremely low (estimated to be less than 1%) if neither of you inherits one of the defective genes.

There is a 50% chance that each additional kid you have will be born with Noonan syndrome if one of you does have a defective gene or has the condition.

A genetic counsellor can discuss your options and the risks involved with having another child. These may consist of:

  • Undergoing a pregnancy test to determine whether the unborn child will have Noonan syndrome
  • A child is adopted
  • Conceiving a child using donor sperm or eggs
  • Preimplantation genetic diagnosis involves fertilizing eggs and testing the results.
  • Only eggs free of the defective Noonan syndrome genes are implanted in the womb in a laboratory.

Home remedies

What Lifestyle Changes Can Help Me Treat Noonan Syndrome?

There are many support groups for Noonan syndrome that you can join and get mental support from others. You will find many such groups by searching on the internet. Apart from this, you should contact your doctor in this regard. Because doctors can tell you the treatment only after seeing your health condition.


Noonan Syndrome is a genetic disorder that affects many aspects of health, from physical symptoms to developmental milestones, psychological and social well-being, and cognitive development. It is important for doctors and healthcare professionals to be aware of the disorder and its subtle symptoms, and to provide comprehensive management and care, including psychological and social support, to patients and their families. An early and accurate diagnosis can also make a big difference in the management and treatment of Noonan Syndrome.

Last verdict from the author

As the author of this information, my last verdict to the readers is to raise awareness about Noonan Syndrome and to remind healthcare professionals and parents to be aware of this disorder and its subtle symptoms. Even though Noonan Syndrome is a rare disorder, it can have a significant impact on the lives of those affected by it. With early and accurate diagnosis, comprehensive management and care, and support for psychological and social well-being, individuals with Noonan Syndrome can lead fulfilling lives. Also, it is important to support ongoing research on Noonan Syndrome to improve diagnosis, management, and treatment options for patients and families affected by this disorder.

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Written by

Greetings, I am Dr. Ashutosh Tripathi, a psychologist with extensive expertise in criminal behavior and its impact on psychological well-being. I hold a Master of Physics (Honors), a Master of Philosophy, a Master of Psychology, and a PhD in Psychology from BHU in India.Over the past 13 years, I have been privileged to serve more than 3200 patients with unique and varied psychological needs. My clinical work is guided by a deep passion for helping individuals navigate complex psychological issues and live more fulfilling lives.As a recognized contributor to the field of psychology, my articles have been published in esteemed Indian news forums, such as The Hindu, The Times of India, and Punjab Kesari. I am grateful for the opportunity to have been honored by the Government of Israel for my contributions to the Psychological Assistance Program.I remain committed to advancing our understanding of psychology and its applications through my ongoing research, which can be found on leading online libraries such as Science Direct, Wiley, Elsevier, Orcid, Google Scholar, and loop Frontiers. I am also an active contributor to Quora, where I share my insights on various psychological issues.Overall, I see myself as a lifelong student of psychology, constantly learning and growing from my patients, colleagues, and peers. I consider it a great privilege to have the opportunity to serve others in this field and to contribute to our collective understanding of the human mind and behavior.

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