What is Noonan Syndrome?
Noonan syndrome is a disorder that involves unusual facial characteristics, short stature, heart defects present at birth, bleeding problems, developmental delays, and malformations of the bones of the rib cage. Noonan syndrome is caused by changes in one of several autosomal dominant genes. A person who has Noonan syndrome may have inherited an altered (mutated) gene from one of his or her parents, or the gene change may be a new change due to an error carried by the egg or sperm or occurring at conception. Alterations in three genes – PTPN11, SOS1 and KRAS – have been identified to date. Noonan syndrome is present in about 1 in 1,000 to 1 in 2,500 people.
