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 inherited in an autosomal dominant manner. Although many individuals with NS have a de novo mutation, an affected parent is recognized in 30%-75% of families. Treatment for individuals who have Noonan syndrome is based on their particular symptoms. Heart problems are treated in the same way as they are for individuals in the general population.
Growth hormone may be used to treat short stature associated with Noonan syndrome. Physiologic replacement for conditions of growth hormone deficiency. Recurrence risk for parents who do not appear to be affected or who have only some facial features of Noonan syndrome is 5%. Gonadal mosaicism may account for this increase over population risk. Affected individuals have a 50% chance of passing on the disorder with each pregnancy. Alterations in four genes - PTPN11, SOS1, RAF1 and KRAS - have been identified to date.