Noonan syndrome

Question 1

How is Noonan Syndrome inherited?

Answer 1

Autosomal Dominant (PTPN 11 gene mutation)

Question 2

What is the classic phenotype of Noonan syndrome?

Answer 2

• Micrognathia
• Deep philtrum
• Wide spaced eyes
• Low set ears
• Pectus carinatum (protruding)
• Lymphedema
• Developmental delay
• Hemivertebrae

Question 3

What ultrasound findings are suspicious for Noonan syndrome?

Answer 3

-Cystic hygroma + Cardiomyopathy = Noonan (seen in 90%)

• Cystic hygroma
• Heart defect (cardiomyopathy and pulmonary stenosis)
• Polyhydramnios
• Micrognathia

Question 4

What is the most common cardiac defect with Noonan Syndrome?

Answer 4

Idiopathic cardiomyopathy (20-33%) with pulmonary stenosis (50%)

Question 5

What is the prognosis for a fetus diagnosed with Noonan syndrome?

Answer 5

• Failure to thrive
• Learning disability
• Mild intellectual impairment
• Delayed puberty