As of 2017, it is estimated that Noonan syndrome occurs in approximately 1 in 1,000 to 2,500 people. It is possible that Noonan syndrome is more prevalent than currently reported due to possible under-diagnosis of individuals with milder presentations.
As of 2017, there are no known high-risk populations for Noonan syndrome.
As of 2017, there is no known carrier frequency for Noonan syndrome.
Frequently Asked Questions About Noonan syndrome
Who should be tested for Noonan syndrome?
Noonan syndrome (NS) should be suspected in individuals with the following key features:
•Characteristic facial features inncluding low-set, posteriorly rotated ears, vivid blue or blue-green irises, and eyes that are often wide-spaced, downslanted, and with epicanthal folds and fullness or droopiness of the upper eyelids (ptosis).
•Short stature
•Congenital heart defect, most commonly pulmonary valve stenosis, atrial septal defect, and/or hypertrophic cardiomyopathy
•Developmental delay
•Broad or webbed neck
•Unusual chest shape with superior pectus carinatum, inferior pectus excavatum
•Widely set nipples
•Cryptorchidism (descended testes) in males
Speak to a genetic counselor or a medical geneticist to learn more about getting tested for Noonan syndrome.
Where did the name Noonan syndrome come from?
Noonan syndrome is named after Jacqueline Noonan, a pediatric cardiologist
What websites have good information about Noonan syndrome?
You can learn more about Noonan syndrome by visiting the following websites:
Noonan syndrome Foundation
[link url="” target=”_blank”>www.teamnoonan.org
Genetics Home Reference
[link url="” target=”_blank”>https://ghr.nlm.nih.gov/condition/noonan-syndrome
National Organization for Rare Disorders (NORD) – Noonan syndrome
[link url="” target=”_blank”>https://rarediseases.org/rare-diseases/noonan-syndrome/
RASopathiesNET
[link url="” target=”_blank”>https://rasopathiesnet.org/
What types of doctors should someone with Noonan syndrome see?
Children with Noonan syndrome may need to see a variety of specialists depending on their symptoms.
Congenital heart defects should be managed by a cardiologist (heart doctor)
Bleeding problems should be monitored by a hematologist
Developmental concerns should be followed by a developmental pediatrician
Growth concerns should be evaluated by an endocrinologist
Vision concerns should be evaluated by an Ophthalmologist
Additional specialists may be needed depending on an individuals specific symptoms.
Speak to a genetic counselor or a medical geneticist to learn more about the specialists an individual with Noonan syndrome should see.
What other syndromes look like Noonan syndrome?
Turner syndrome is found only in females. It is differentiated from Noonan syndrome by demonstration of a sex chromosome abnormality on cytogenetic (chromosome) studies. In Turner syndrome, kidney problems are more common, developmental delay is much less frequently found, and left-sided heart defects occur more often.
Watson syndrome is characterized by short stature, pulmonary valve stenosis, variable intellectual development, and café au lait spots. Watson syndrome also overlaps with neurofibromatosis type 1 .
Cardiofaciocutaneous (CFC) syndrome and Noonan syndrome have the greatest overlap in features. CFC syndrome has similar cardiac and lymphatic findings. In CFC syndrome, intellectual disability is usually more severe, gastrointestinal problems are more severe, and bleeding problems are rare. Four genes are known to cause CFC syndrome including BRAF (~75%), MAP2K1 and MAP2K2 (~25%), and KRAS (<2%-3%).
Costello syndrome shares features with both Noonan syndrome and Cardiofaciocutaneous (CFC) syndrome. Many individuals with Costello syndrome have had genetic testing and no changes in PTPN11 have been found. Genetic changes in HRAS have been shown to cause Costello syndrome.
Noonan syndrome-like disorder with or without JMML is caused by variants in CBL. This condition is characterized by neurologic features, predisposition to juvenile myelomonocytic leukemia, low risk of cardiac defects, reduced growth, and cryptorchidism (undescended testes).
Neurofibromatosis type 1 (NF1) shares some features with Noonan syndrome, including short stature, learning difficulties, and café au lait spots.
Speak to a genetic counselor or a medical geneticist to learn more about these conditions.
What kidney problems do children with Noonan syndrome have?
Kidney (renal) differences are seen in 11% of individuals with Noonan syndrome. Dilatation of the renal pelvis is most common. Duplex collecting systems, minor rotational anomalies, distal ureteric stenosis, renal hypoplasia (small kidneys), unilateral renal agenesis (missing one kidney), unilateral renal ectopia (one kidney in a different location than expected), and bilateral cysts with scarring are reported less commonly.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
What is the usual abbreviation for Noonan syndrome?
Noonan syndrome may be abbreviated as NS.
What is the testing for Noonan syndrome?
If a diagnosis of Noonan syndrome is suspected in an infant or child, a genetics team can perform genetic testing to confirm a diagnosis. Genetic testing for Noonan sydndrome may be performed by a multi-gene panel, serial single-gene testing, and more comprehensive genomic testing.
A multi-gene panel that includes multiple genes associated with Noonan syndrome is the test of choice for an individual suspected of having Noonan syndrome. The features of Noonan syndrome have significant overlap with cardiofaciocutaneous syndrome (CFC) and Costello syndrome, most available panels include the genes for these diagnoses, too.
Serial single-gene testing can be considered if panel testing is not feasible. Approximately 50% of individuals with Noonan syndrome will have a pathogenic mutation (change) in the PTPN11 gene. Single-gene testing starting with PTPN11 would be the next best first test. Appropriate serial single-gene testing if PTPN11 testing is non-diagnostic can be determined by the individual’s features.
More comprehensive genomic testing (if available) including whole-exome sequencing (WES) or whole-genome sequencing (WGS) may be considered if use of a multi-gene panel and/or serial single-gene testing fails to confirm a diagnosis in an individual with features of Noonan syndrome.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
What is the most common gene for Noonan syndrome?
Approximately 50% of individuals with Noonan syndrome have been found to have a mutation or change in the PTPN11 gene.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
What is Noonan syndrome?
Noonan syndrome is characterized by facial features, short stature, congenital heart defect, and developmental delay. Other findings can include broad or webbed neck, unusual chest shape with superior pectus carinatum and inferior pectus excavatum, cryptorchidism (undescended testes), bleeding problems, and eye differences.
Birth length is usually normal, but final adult height approaches the lower limit of normal. Congenital heart disease occurs in 50%-80% of individuals. Pulmonary valve stenosis, often with dysplasia, is the most common heart defect and is found in 20%-50% of individuals. Hypertrophic cardiomyopathy, found in 20%-30% of individuals, may be present at birth or develop in infancy or childhood. Other structural defects include atrial and ventricular septal defects, branch pulmonary artery stenosis, and tetralogy of Fallot. Up to 25% of individuals with Noonan syndrome have mild intellectual disability. Language impairments are more common in Noonan syndrome than in the general population.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
What health problems are seen in Noonan syndrome?
Symptoms of Noonan syndrome can include:
What gene change causes Noonan syndrome?
Many different genes have been associated with Noonan syndrome and new genes are continually discovered. Currently a genetic change can be found in approximately 90% of individuals with Noonan syndrome.
Approximately 88.5% of individuals with a clinical diagnosis of Noonan Syndrome are expected to have a mutation or change in one of six genes, PTPN11, SOS1, RAF1, RIT1, NRAS, CBL, or KRAS. Mutations in PTPN11 have been found in approximately 50% of affected individuals. Mutations in SOS1 are seen in about 10% of patients with Noonan syndrome and 20% of those who do not have a mutation in PTPN11. Mutations in RAF1 occur in as many as 17% of Noonan syndrome patients. Mutations in KRAS account for approximately 1-2% of individuals with Noonan syndrome. Mutations in NRAS account for 0.5% and mutations in CBL account for approximately 1% of individuals with Noonan syndrome. The overall frequency of RIT1 pathogenic variants in individuals with a diagnosis of Noonan syndrome has not been well established. Additional genes have also been reported in Noonan syndrome, but occur at a lower frequency.
Speak to a genetic counselor or a medical geneticist to learn more about genetics testing for Noonan syndrome.
What do you do after being diagnosed with Noonan syndrome?
At the time of diagnosis the following evaluations are recommended:
Consultation with a clinical geneticist and/or genetic counselor
Complete physical and neurologic examination
Plotting of growth parameters on Noonan syndrome growth charts
Cardiac evaluation with echocardiography and electrocardiography (ECG)
Ophthalmologic evaluation
Hearing evaluation
Coagulation screen to include CBC with differential, PT/PTT
Renal ultrasound examination and a urinalysis if urinary tract abnormalities are found
Clinical and radiographic evaluation of spine and rib cage
Brain and cervical spine MRI if neurologic symptoms are present
Multidisciplinary developmental evaluation
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
What are the other names for Noonan syndrome?
Other names for Noonan syndrome are:
Male Turner syndrome
Turner-like syndrome
Ullrich-Noonan syndrome
Pseudo-Turner syndrome
What are the bleeding problems in Noonan syndrome?
Most individuals with Noonan syndrome have a history of abnormal bleeding or bruising. Approximately one third of all individuals with Noonan syndrome have one or more coagulation defects. Problems with blood clotting may results in severe bleeding with surgery, mild bruising, or laboratory abnormalities with no clinical significance.
Speak to a genetic counselor or a medical geneticist to learn more about bleeding problems in Noonan syndrome.
Should other family members have testing for Noonan syndrome?
Noonan syndrome is inherited from a parent in 30%-75% of families. Once a child has been diagnosed with Noonan syndrome it is important for parents to get tested. The risk to siblings of an individual with Noonan syndrome depends on the genetic status of the parents. If a parent is affected, the risk to their other children is 50%.
When a genetic change is found to be de novo, not inherited from either parent, there is a residual risk for germline mosaicism in a future pregnancy. This term means that the gene change could be present in some of the mother’s eggs or some of the father’s sperm. The residual risk for germline mosaicism is approximately 1%.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
Is there newborn screening for Noonan syndrome?
Noonan syndrome is not tested for at birth unless there is a specific concern based on a baby’s features. These features may include heart defects and characteristic facial features.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
Is there is Saliva test for Noonan syndrome?
Testing for Noonan syndrome is usually performed through a blood test, but may also be available on a saliva sample. Once a gene change is found, then testing could be done in family members through saliva or blood.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
Is there clinical research happening for Noonan syndrome?
To learn more about clinical research happening for Noonan syndrome visit clinicaltrials.gov.
Support groups may also have information on current research.
Noonan syndrome Foundation
[link url="” target=”_blank”>www.teamnoonan.org
RASopathiesNET
[link url="” target=”_blank”>https://rasopathiesnet.org/
Speak to a genetic counselor to learn more about current research for Noonan syndrome.
Is puberty delayed in Noonan syndrome?
Male pubertal development and subsequent fertility may be normal, delayed, or inadequate. Deficient spermatogenesis may be related to cryptorchidism (undescended testes), which is noted in 60% to 80% of males.
Puberty may be delayed in females, but fertility is normal.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
Is Noonan syndrome genetic testing covered by my insurance company?
In the United States, most health insurance companies will cover most testing costs. Your doctor or genetic counselor might need to write a letter to explain why testing is needed. Many people are worried that the results of the genetic test will affect the chances of getting health insurance. The federal law known as Genetic Information Nondiscrimination Act (GINA) prohibits health insurers and employers from using your genetic information, which includes the following.
1. Employers cannot deny you a job because of the results of genetic testing
2. Health insurers cannot use genetic testing to deny you coverage or set your insurance rates
3. Employers and insurers cannot require you to have genetic testing.
In the United States, no federal legislation directly addresses the issue of genetic testing and life insurance. Although a few states have passed statewide laws restricting the use of genetic information in life, disability and long-term care insurance, GINA does not cover these types of insurance and it is recommended that you explore life insurance options before genetic testing.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing and insurance coverage for Noonan syndrome.
State by state information on genetic testing and life, disability, and long term care insurance can be found at the National Conference of State Legislatures website.
If my child didn’t get Noonan syndrome from a parent, why is it called a genetic disorder?
Noonan syndrome is called a genetic disorder because we know it is caused by a change or mistake in the body’s genetic instructions. However, just because it has a genetic cause, that does not mean it is hereditary, or inherited from a parent.
If I am unaffected, do my other children need tested for Noonan syndrome?
Noonan syndrome is inherited from a parent in 30%-75% of families. Once a child has been diagnosed with Noonan syndrome it is important for parents to get tested. The risk to siblings of an individual with Noonan syndrome depends on the genetic status of the parents. If a parent is affected, the risk to their other children is 50%.
When a genetic change is found to be de novo, not inherited from either parent, there is a residual risk for germline mosaicism in a future pregnancy. This term means that the gene change could be present in some of the mother’s eggs or some of the father’s sperm. The residual risk for germline mosaicism is approximately 1%.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
If genetic testing is negative, does this mean I don’t have Noonan syndrome or my child doesn’t?
If a diagnosis of Noonan syndrome is suspected but genetic testing does not find a gene change this does not mean that someone does not have Noonan syndrome. It means that genetic testing did not find a genetic cause; however genetic testing is not perfect. Approximately 10% of individuals with a clinical diagnosis of Noonan syndrome will not have an identifiable gene change. Additional genes for Noonan syndrome may be discovered in the future.
Speak to a genetic counselor or a medical geneticist if you are concerned about Noonan syndrome.
How to you get Noonan syndrome?
Many individuals with Noonan syndrome have a de novo (brand new) pathogenic variant. An affected parent is identified in 30%-75% of families.
Noonan syndrome is inherited in an autosomal dominant manner. This means that one copy of a gene change is enough to cause symptoms of the condition. Once an individual is identified with an autosomal dominant condition (such as Noonan syndrome) each of their future children has a 50% risk to inherit the same gene change.
Speak to a genetic counselor or a medical geneticist to learn more about the recurrence risk of Noonan syndrome.
How short are people with Noonan syndrome?
Length at birth is usually normal for babies with Noonan syndrome. Growth failure is often obvious during the first year of life. Final adult height approaches the lower limit of normal. One study suggests that 30% of individuals with Noonan syndrome fall within the normal adult height range, while more than 50% of females and nearly 40% of males have an adult height below the third percentile.
Speak to a genetic counselor or a medical geneticist to learn more about short stature in Noonan syndrome.
How many tests are there for Noonan syndrome?
There are several genetic tests for Noonan syndrome.
A multi-gene panel that includes multiple genes associated with Noonan syndrome is the test of choice for an individual suspected of having Noonan syndrome. The features of Noonan syndrome have significant overlap with cardiofaciocutaneous syndrome (CFC) and Costello syndrome, most available panels include the genes for these diagnoses, too.
Serial single-gene testing can be considered if panel testing is not feasible. Approximately 50% of individuals with Noonan syndrome will have a pathogenic mutation (change) in the PTPN11 gene. Single-gene testing starting with PTPN11 would be the next best first test. Appropriate serial single-gene testing if PTPN11 testing is non-diagnostic can be determined by the individual’s features.
More comprehensive genomic testing (if available) including whole-exome sequencing (WES) or whole-genome sequencing (WGS) may be considered if use of a multi-gene panel and/or serial single-gene testing fails to confirm a diagnosis in an individual with features of Noonan syndrome.
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
How many people have Noonan syndrome?
Noonan syndrome occurs in approximately 1 in 1,000 to 2,500 individuals.
How long to people with Noonan syndrome live?
Children with Noonan syndrome are expected to have a normal life span. It is important that children see the right doctors to make sure any necessary surgeries or treatments are done to avoid complications later in life.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
How do you treat Noonan syndrome?
Treatment for the symptoms of Noonan syndrome generally does not differ from treatment in the general population.
The treatment of heart defects is generally the same as in the general population.
Developmental delay and learning disabilities should be addressed by early intervention programs and individualized education strategies.
Consider endocrinology consultation for evaluation of short stature and discussion of growth hormone treatment.
Guidelines have been published for the Management of Noonan syndrome.
Speak to a genetic counselor or a medical geneticist to learn more about the treatment and management of Noonan syndrome.
How do I find other people with Noonan syndrome?
Your can find other individuals with Noonan syndrome by visiting support groups. Two great resources are below:
Noonan syndrome Foundation
[link url="” target=”_blank”>www.teamnoonan.org
RASopathiesNET
[link url="” target=”_blank”>https://rasopathiesnet.org/
Speak to a genetic counselor to learn more about support groups for Noonan syndrome.
How do I find clinical research on Noonan syndrome?
To learn more about clinical research happening for Noonan syndrome visit clinicaltrials.gov.
Speak to a genetic counselor to learn more about current research for Noonan syndrome.
Does Noonan syndrome affect boys and girls?
Noonan syndrome occurs in males and females equally.
Does my child with Noonan syndrome need special education?
Most children do well in a normal educational setting, but 25% have learning disabilities and 10% to 15% require special education. Intellectual abilities are mildly lowered in children with Noonan syndrome. IQ scores below 70 are seen in 6% to 23%
Articulation deficiency is also common in Noonan syndrome (72%) but usually responds well to speech therapy. Language delay may be related to hearing loss or articulation deficiencies. Children typically say their first words around 15 months and simple two-word phrases around age 31 to 32 months.
Does developmental delay occur in Noonan syndrome?
Early developmental milestones may be delayed in Noonan syndrome. Delays may occur because of joint hyperextensibility and hypotonia. The average age for sitting unsupported is around ten months and for walking is 21months. About 50% of school-aged children meet diagnostic criteria for a developmental coordination disorder and impaired manual dexterity is significantly correlated with verbal and nonverbal intellectual functioning.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
Do problems with feeding occur in Noonan syndrome?
Infants with Noonan syndrome frequently have feeding difficulties. This period poor weight gain may last for up to 18 months.
Speak to a genetic counselor or a medical geneticist to learn more about feeding problems in Noonan syndrome.
Did anything I do during my pregnancy cause Noonan syndrome?
There is nothing that you do to cause or prevent Noonan syndrome from happening. When an egg and a sperm meet to form a baby, there is genetic information from the mother and from the father that combine together. This has to happen in a very specific way and at the exact right time. Sometimes mistakes in the genetic information happen in this process. This change or mistake in the genetic information has been present from the very start of a baby’s life.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
Can you detect Noonan syndrome on a prenatal ultrasound?
Comprehensive ultrasound examination around 18 to 20 weeks’ gestation may be able to detect some features of Noonan syndrome. Prenatal features are nonspecific but may include polyhydramnios, hydronephrosis, pleural effusion, edema, heart defects, cystic hygroma, and increased nuchal translucency. The presence of these findings should suggest the diagnosis of Noonan syndrome. In pregnancies with normal chromosomes, the diagnosis of Noonan syndrome will be made in approximately 5%-15% of cases with nuchal edema detected in the first trimester and 10% of second-trimester pregnancies with a cystic hygroma. However, the absence of these features on ultrasound does not rule out the diagnosis of Noonan syndrome. Ultrasound is considered a screening test and is not diagnostic.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
Can I test my pregnancy for Noonan syndrome?
If you have had a previous child with Noonan syndrome or a family member has, and the genetic cause is known, testing can be done in a future pregnancy. Testing options include chorionic villus sampling (CVS) and amniocentesis. CVS involves removing a piece of the placenta for genetic testing. CVS can be performed around 10-12 weeks of gestation. With CVS there is a small risk for confined placental mosaicism. This means that a genetic change could be present in the placenta that is not present in the baby or that a genetic change could be present in the baby that is not present in the placenta. The risk for confined placental mosaicism is approximately 1%. Amniocentesis involves taking a sample of amniotic fluid found for genetic testing. This testing can be performed starting at 15 weeks of gestation. Because both CVS and amniocentesis are invasive, there is a small risk for miscarriage
Speak to a genetic counselor or a medical geneticist to learn more about prenatal testing for Noonan syndrome.
Are there support groups for Noonan syndrome?
There are several support groups for Noonan syndrome.
Noonan syndrome Foundation [link url="www.teamnoonan.org” target=”_blank”>www.teamnoonan.org
RASopathiesNET https://rasopathiesnet.org/
Are there learning delays in Noonan syndrome?
Most children do well in a normal educational setting, but 25% have learning disabilities and 10% to 15% require special education. Intellectual abilities are mildly lowered in children with Noonan syndrome. IQ scores below 70 are seen in 6% to 23%
Articulation deficiency is also common in Noonan syndrome (72%) but usually responds well to speech therapy. Language delay may be related to hearing loss or articulation deficiencies. Children typically say their first words around 15 months and simple two-word phrases around age 31 to 32 months.
Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
Are there heart defects in Noonan syndrome?
Congenital heart disease is seen in 50% and 80% of individuals with Noonan syndrome.
Pulmonary valve stenosis is the most common heart defect in Noonan syndrome, found in 20%-50% of individuals. This finding may be isolated or associated with other heart defects.
Hypertrophic cardiomyopathy is found in 20% to 30% of individuals with Noonan syndrome. The median age at diagnosis is five months and more than 50% of individuals with Noonan syndrome and hypertrophic cardiomyopathy are diagnosed by age six months.
Other structural defects frequently observed include atrial and ventricular septal defects, branch pulmonary artery stenosis, tetralogy of Fallot, and coarctation of the aorta.
An electrocardiographic (EKG or ECG) abnormality is documented in approximately 90% of individuals with Noonan syndrome and may be present without structural heart defects.
Speak to a genetic counselor or a medical geneticist to learn more about heart defects in Noonan syndrome.
Are there eye problems in Noonan syndrome?
Eye differences including strabismus (crossed eye), refractive errors (including nearsightedness, farsightedness, and astigmatism), amblyopia (laze eye), and nystagmus (involuntary eye movements) occur in up to 95% of individuals with Noonan syndrome.
Speak to a genetic counselor or a medical geneticist to learn more about eye problems in Noonan syndrome.
Are there experts in Noonan syndrome?
There is currently no center of excellence for Noonan syndrome.
It is important that children with Noonan syndrome have a consultation with a medical geneticist and/or genetic counselor to make a diagnosis and learn about experts in the medical community. Speak to a genetic counselor or a medical geneticist to learn more about Noonan syndrome.
Are genetic testing results for Noonan syndrome private?
Some people may feel concerned about maintaining the privacy of their genetic information. Your doctor isn’t allowed to tell anyone that you have had a genetic test or the results without your consent; however, your health insurance company can request your medical records if you give them permission. Consider discussing privacy concerns with your genetic counselor or geneticist.
Are different features associated with different genes for Noonan syndrome?
Pulmonary stenosis is more likely to be present in individuals who have mutations in PTPN11. Hypertrophic cardiomyopathy is less common inindividuals with PTPN11 gene changes.
Changes in PTPN11 have also been linked to short stature, pectus deformity (chest wall deformities), easy bruising, characteristic facial appearance, and cryptorchidism (undescended testes).
Approximately 80% of individuals with a mutation in the RAF1 gene are expected to develop hypertrophic cardiomyopathy.
Individuals with a mutation in CBL or PTPN11 may have an increased risk for developing juvenile myelomonocytic leukemia (JMML).
Speak to a genetic counselor or a medical geneticist to learn more about genetic testing for Noonan syndrome.
