Noonan Syndrome Flashcards
What is Noonan Syndrome?
Noonan Syndrome is a genetic disorder affecting the RAS/MAPK signalling pathway. It is a cause of short stature. Its clinical presentation is similar to that of Turner’s Syndrome, but affects both sexes.
Reference: The Science of Paediatrics [1st Edition], p. 221; Nelson’s Paediatrics [20th Edition], p.622.
Image Source: Access Paediatrics
What is the underlying genetic defect in Noonan Syndrome?
Mutations of genes including:
PTPN11 (12q24.1)
SOS1
KRAS
RAF-1
It is inherited in an autosomal dominant pattern.
How does Noonan Syndrome present?
Signs of Noonan Syndrome include:
Short stature
Scoliosis
Webbed neck
Low hairline
Low set ears
Ptosis
Nystagmus
Blue/green eyes
Pectus excavatum
Cubitus valgus
Congenital Heart Defects
Noonan generally results in right heart defers (i.e. Pulmonary stenosis), whereas Turner’s manifests left-heart defects (Coarctation of the aorta). Other defects includ hypertrophic cardiomyopathy and ASD.
Think: Turn Left, BRight Noon
Cryptochidism
Delayed puberty
Mild educational difficulties
Coagulation defects
Affecting Factors VII, XI, XII
Think of a blood-red (coagulation) sun hanging low (height and ears) in the sky at noon (Noonan’s).
Reference: The Science of Paediatrics [1st Edition], p. 221; PasTest.
How is Noonan Syndrome managed?
Human Growth Hormone
Particularly if fall below 2nd centile for height
Reference: Nelson’s Paediatrics [20th Edition], p. 2737.
