Cardiac Manifestations of Noonan Syndrome

Noonan syndrome NS, a RASopathy, is commonly seen in association with cardiovascular abnormalities, with structural defects and/or cardiomyopathy present in 80-90-% of cases. Though a wide spectrum of cardiac pathology has been reported, pulmonary stenosis is the most common structural abnormality and more likely to be seen in PTPN11 mutations. Hypertrophic cardiomyopathy is the second most common and is more often associated with RAF1 mutations. Cardiac disease tends to be more progressive in infants and children with NS and therefore close cardiology follow-up is indicated. In general, the earlier the presentation, the more severe the phenotype and worse the long term prognosis. As genotype phenotype associations are being better understood, the mechanisms for development of cardiomyopathy are also becoming elucidated, raising the possibility of medical therapies targeted at the involved pathway.