Noonan Syndrome

Noonan syndrome is a genetic condition. There are a number of different genes that cause Noonan syndrome. The majority for cases are inherited in an autosomal dominant way. There is variation in the signs and symptoms of Noonan syndrome, depending on the underlying cause.



  • Short stature
  • Broad forehead
  • Downward sloping eyes with ptosis
  • Hypertelorism (wide space between the eyes)
  • Prominent nasolabial folds
  • Low set ears
  • Webbed neck
  • Widely spaced nipples


Associated Conditions

  • Congenital heart disease, particularly pulmonary valve stenosis, hypertrophic cardiomyopathy and ASD
  • Cryptorchidism (undescended testes) can lead to infertility. Fertility is normal in women.
  • Learning disability
  • Bleeding disorders
  • Lymphoedema
  • Increased risk of leukaemia and neuroblastoma



There is no treatment for the underlying genetic defect. Management is supportive with involvement of the multidisciplinary team. The main complication is congenital heart disease and often patients will require corrective heart surgery.


Last updated January 2020