Noonan syndrome is a clinically diverse autosomal dominant disorder characterized by short stature, mental retardation, sexual dysplasia (cryptorchidism), ocular, congenital cardiovascular anomalies, skeletal anomalies, bleeding tendencies, lymphatic duct dysplasia, thick neck or neck purpura, complex chest deformities, and unique facial features. The incidence of Noonan syndrome is estimated to be between 1 in 1,000 and 1 in 2,500 live births, and was previously known as male Turner syndrome, but many female patients have since been identified. Patients with Noonan syndrome have a higher rate of mental retardation compared to Turner syndrome.