Noonan syndrome is a condition that is characterized by mildly unusual facial characteristics, short stature, heart defects, bleeding problems, skeletal malformations, and many other signs and symptoms. 15 studies were conducted in which growth hormone (GH) therapy was used in children with Noonan syndrome. Data show consistent increases in mean height standard deviation score (SDS), with first-year changes of up to 1.26 SDS. Among studies reporting adult or near-adult height, GH therapy over 5-7 years resulted in adult height SDS from -0.6 to -2.1, with up to 60% of subjects in some studies achieving adult height within 1 SDS of mid-parental height.
There is currently no single treatment for Noonan syndrome, but it's often possible to successfully manage many aspects of the disorder. Severe heart defects may need to be repaired with surgery, and growth hormone medication may be used to help prevent restricted growth. 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.