The Most Common Rare Syndrome You've Never Heard Of
I had never heard of Noonan Syndrome before having Abby. It wasn't until a couple of days after her birth, once we had been transferred to Cincinnati Children's, that the name first came into my awareness. Though the geneticists were baffled by Abby's particular assortment of complications, the cardiologists were focused on her hypertrophic cardiomyopathy and immediately knew what the underlying issue was: Noonan's. Though it took about two months to receive confirmation, the cardiologists were entirely correct: Abby has a gene mutation that causes what those in the Noonan's community refer to as "the most common rare syndrome you've never heard of."
Seriously, for never having heard of Noonan Syndrome, it is remarkably common, occurring in 1 of every 1,000-2,500 live births - really not all that more rare than Down Syndrome, which it seems most people are familiar with. The lack of knowledge surrounding Noonan Syndrome may be in part to its extreme variability. The effects of Noonan Syndrome can present themselves through certain physical attributes, but are also seen in the way many bodily systems are influenced. According to the Noonan Syndrome Foundation:
"People with NS may experience bleeding issues, congenital heart defects including hypertrophic cardiomyopathy and/or pulmonary valve stenosis, lymphatic abnormalities, small stature/growth issues, feeding and gastrointestinal issues, failure to thrive, hypertelorism, learning disorders, autism, unexplained chronic pain, chiari malformation, hypotonia, ptosis, skeletal malformations, laryngomalacia, tracheomalacia, opthamology issues, orthopaedic issues, oncology issues and much, much more."
As far as I can tell, that seems to pretty well encompass the entire body. Abby has the misfortune of suffering from quite a few of these maladies, which account for the SIX medical appointments that she has this week alone. We've joked (sort of) that the only department Abby hasn't consulted with at CCHMC is podiatry.
Though the extensive nature of Noonan Syndrome can be overwhelming, I am so thankful for her diagnosis: it has allowed us to be proactive in ways that we would not have known necessary without it. For instance, the bleeding disorders associated with Noonan's can present themselves at any point throughout a person's life. Before any surgical procedure, Abby will need to be tested to assess her blood's ability to clot so that we don't run into any life-threatening issues of blood-loss. It also prompted the hematology team to search for a particular type of leukemia (JMML) that frequently affects people with NS when they saw that her white blood cell count was chronically high. It turned out that she did not have JMML at that time, but it's certainly something we need to keep an eye out for. Though we don't think that the label of Noonan Syndrome (or any other issue, for that matter) needs to define Abby, we do think it's important to be informed and aware of how the complications may affect her.
The genetics behind Noonan Syndrome are somewhat complicated. Unlike conditions like Down Syndrome, people with Noonan Syndrome have a typical number of chromosomes. There is however a mutation that occurs of one of a few different genes (PTPN11, SOS1, RAF1, NRAS, KRAS, or BRAF) that results in the presence of Noonan's. It is not something that can be "cured" or "grown out of" - it is a part of their DNA and is integral to their genetic makeup. Noonan Syndrome can occur in a person via a couple of different routes. The syndrome is considered autosomal dominant, in that a person with Noonan Syndrome has a 50% chance of passing their particular Noonan-causing gene mutation to their offspring. It can also occur spontaneously, with no family history, and no apparent trigger. In Abby's case, the cause is the latter. Jameson and I had testing done to determine if either of us carry the KRAS gene mutation that Abby has, and it was determined that we do not. We have absolutely no idea what caused her particular case, it was simply something in the way the cosmos aligned at her conception that determined that she would have Noonan Syndrome. If we were to have more children, the likelihood that they would have Noonan's is the same as it was for Abby - totally unexpected, and extremely unlikely.
If, like me, you weren't familiar with Noonan Syndrome before Abby, I encourage you to continue learning about it. Considering how common it actually is, it's entirely possible that you know others with Noonan Syndrome as well. I discovered that I had a fellow mom friend with a child with Noonan's, but just hadn't realized it before! Check out the following link to explore Noonan's further:
Noonan Syndrome Foundation