One of the most common questions I’m asked—by both medical professionals and people outside the healthcare field—is: What is Noonan Syndrome?
Noonan Syndrome (NS) is a genetic condition classified as a RASopathy, a group of disorders caused by mutations in genes that are part of the RAS/MAPK pathway, which controls cell growth and development. These mutations can disrupt normal development in various parts of the body.
In most cases, Noonan Syndrome is caused by a spontaneous genetic change in the egg or sperm. This means that many children with NS are the first in their family to have the condition. However, NS can also be inherited in an autosomal dominant pattern—meaning that if a parent has the condition, there is a 50% chance of passing it on to their child.
Because NS is genetic and now part of my family’s medical history. This means that any children I may have will each carry a 50% chance of inheriting the condition, and it can be passed on through future generations as well.
In my own case, there is no known family history of NS. My parents have never been tested and are both healthy, with no known related conditions. My diagnosis came shortly after birth, but the specific gene was diagnosed through genetic testing, which revealed a mutation in the RIT1 gene—a less common type of Noonan Syndrome, accounting for fewer than 5% of diagnosed cases.
Although considered a rare disorder, Noonan Syndrome is one of the more commonly diagnosed rare genetic conditions. It affects approximately 1 in 2,500 births in the UK, highlighting its presence within the broader category of rare diseases.
There are many different mutations of NS which are listed below and their statistics.
- BRAF <2%
- KRAS <5%
- LZTR1 ~8%
- MAP2K1 <2%
- MRAS <1%
- NRAS <1%
- PTPN11 50%
- RAF1 5%
- RASA2 Unknown
- RIT1 5%
- RRAS2 <1%
- SOS1 10%
- SOS2 ~4%
As explained in previous post there are many medical and physical issues associated with NS.
- Eye anomalies
- Short stature
- Hypotonia
- Joint hyperextensibility
- Pectus anomaly effects majority of ns patients. Characteristic pectus deformity of the chest: pectus carinatum superiorly & pectus excavatum inferiorly
- Cryptorchidism in males
- Congenital heart disease – 25%-71% of affected persons have pulmonary valve stenosis, often with pulmonary valve dysplasia.
- Hearing loss
- Hypertrophic cardiomyopathy
- Learning disability
- Renal anomalies
- Abnormal bleeding or bruising
Growing Awareness of Noonan Syndrome: A Personal Reflection
I follow several social media pages dedicated to Noonan Syndrome (NS)—a condition that belongs to a group of genetic disorders known as RASopathies. One thing that stands out to me on these platforms is the number of young children featured, many of whom are living with complex medical needs due to NS.
This raises a question I often find myself asking:
Has Noonan Syndrome become more widely recognized around the world, or are more families simply choosing to share their stories in an effort to raise awareness?
Over the years, increased access to genetic testing has led to earlier diagnoses and greater visibility for conditions like NS. At the same time some social media has empowered families to share their journey—something that wasn’t possible even a decade ago. This public sharing plays a crucial role in raising awareness and reducing the isolation many families feel.
My Personal Experience
Seeing the struggles of others on these pages often make me think. Many individuals with NS face significant medical challenges—some spending extended periods in hospital, undergoing surgeries, or living with severe symptoms.
In comparison, I’ve been incredibly fortunate.
As a baby, I don’t remember the surgeries or the pain, but my parents do. The emotional toll of watching their child undergo procedures and spending long periods away from home has never left them. It’s something we still talk about today. While I may not carry those early memories, the experience shaped our family in profound ways.
A Global Condition
Another thing I’ve noticed on these pages is the large number of American families represented. This isn’t surprising when you consider that Noonan Syndrome was first identified by an American cardiologist, Dr. Jacqueline Noonan, in 1963.
While it may appear more widely known in the United States—perhaps due to the visibility of American families on social media—it’s important to note that awareness remains a global challenge.
Delayed or sometimes no diagnoses are still common, even in countries with advanced healthcare systems. In fact, much of the research we rely on today has come from U.S. institutions like the National Institutes of Health (NIH), which have contributed significantly to our understanding of the condition.
These platforms not only give us a voice—they give others the chance to understand.
As you may have noticed a lot of the links and information I have put into this page are American and this is why. This is why unexpected hospital trips or new locally diagnosed issues with me are so complex and long winded, sadly here in the UK it is not as well-known and not enough awareness.
RASopathy
The term RASopathy, was originally created to describe a phenotypically similar group of medical genetic syndromes caused by germline pathogenic variants in components of the RAS/mitogen-activated protein kinase (RAS/MAPK) pathway.
Collectively, the RASopathies represent one of the largest groups of multiple congenital anomaly syndromes known. Noonan syndrome (NS) or an NS spectrum can be caused by a mutation in numerous genes as stated above in the forms of NS.
Cardio-Facio-cutaneous syndrome (CFC) is caused by activating mutations in multiple genes, including BRAF, MAP2K1/MEK1, MAP2K2/MEK2, KRAS and possibly YWHAZ.
Other RASopathies, including neurofibromatosis type 1 (NF1), Noonan syndrome with multiple lentigines (NSML), Costello syndrome (CS), Legiius syndrome, SYNGAP1 and central conducting lymphatic anomalies (CCLA), are caused by alterations in one or two genes in the RAS pathway.
All causative pathogenic variants are part of the complex and well-studied RAS/MAPK signal transduction pathway, which is essential for development and is implicated in oncogenesis. What makes the RASopathies unique is the pathway-based, mechanistic approach to defining medical genetic syndromes as opposed to the isolated one gene–one syndrome approach.
I research.
