Autosomal Dominant condition
Ras-MAPK pathway Defect
Due to mutation in
PTPN11 protein-tyrosine phosphatase,non-receptor-type 11) gene on chromosome 12.
10–15% are caused by SOS1 (son of seven-less homologue 1 (Drosophila), on
chromosome and RAF1
NS is often associated with advanced paternal age
Karyotype is usually normal.
Male: Female - 4:1
Phenotypically looks like Turner
So if male and looks like Turner think of Noonan.
Pulmonary valve stenosis (Most common)
Branch pulmonary artery stenosis
Webbed or short neck
Pectus excavatum or carinatum
Wide carrying angle (cubitus valgus)
Short stature in 80%
Low set ears and posteriorly rotated