Individuals with Noonan syndrome (NS) have facial dysmorphology, which may include hypertelorism, downward slanting eyes, epicanthal folds, and low-set and posteriorly rotated ears. A variety of cardiac defects may be present, including pulmonary stenosis, patent ductus arteriosus, hypertrophic cardiomyopathy, and coarctation of the aorta. Other features include short stature, pterygium colli, short, webbed neck, deafness, motor delay, and bleeding diathesis. Lymphedema may be present prenatally. Noonan syndrome shares some clinical features with cardio-facio-cutaneous (CFC) and Costello syndrome. However, Noonan syndrome patients typically have milder cognitive deficits and fewer ectodermal problems.
Individuals with this specific phenotype exhibit features consistent with Noonan syndrome as well as growth hormone deficiency, cognitive deficits, distinctive hyperactive behavior, loose anagen hair, darkly pigmented skin with eczema or scaling, and a significant overrepresentation of mitral valve and septal cardiac defects.