Noonan syndrome
| Noonan syndrome | |
|---|---|
| Other names | Male Turner syndrome, Noonan–Ehmke syndrome, Turner-like syndrome, Ullrich–Noonan syndrome |
| A 12-year-old girl with Noonan syndrome, displaying typical webbed neck and double structural curve with rib deformity. | |
| Specialty | Medical genetics, pediatrics |
| Symptoms | Mildly unusual facial features, short height, congenital heart disease, bleeding problems, skeletal malformations |
| Complications | Leukemia |
| Usual onset | Present at birth |
| Types | Type 1 to 6 |
| Causes | Genetic mutation (autosomal dominant) |
| Diagnostic method | Suspected based on symptoms, confirmed with genetic testing |
| Differential diagnosis | Cardiofaciocutaneous syndrome, Turner syndrome, Costello syndrome, neurofibromatosis type 1 |
| Treatment | Based on the symptoms |
| Medication | Growth hormone |
| Prognosis | Depends on the severity of heart problems |
| Frequency | 1 in 1000 (1 in 2,000 severe disease) |
| Named after | Jacqueline Noonan |
Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored eyes, low-set ears, a short neck, and a small lower jaw. Heart problems may include pulmonary valve stenosis. The breast bone may either protrude or be sunken, while the spine may be abnormally curved. Intelligence is often normal. Complications of NS can include leukemia. Some of NS' symptoms are shared with Watson syndrome, a related genetic condition.
A number of genetic mutations can result in Noonan syndrome. The condition may be inherited as an autosomal dominant condition or occur as a new mutation. Noonan syndrome is a type of RASopathy, the underlying mechanism for which involves sustained activation of the RAS/MAPK cell signaling pathway. The diagnosis may be suspected based on symptoms, medical imaging, and blood tests. Confirmation may be achieved with genetic testing.
No cure for NS is known. Treatment is based on the symptoms and underlying problems, and extra support in school may be required. Growth hormone therapy during childhood can increase an affected person's final height. Long-term outcomes typically depend on the severity of heart problems.
An estimated 1 in 1,000 people are mildly affected by NS, while about 1 in 2,000 have a more severe form of the condition. Males appear to be affected more often than females. The condition was named after American pediatric cardiologist Jacqueline Noonan, who described her first case in 1963.