This is a multisystem disorder manifest in skin, heart, skeletal, genital, neurologic and auditory systems. Generalized lentiginosis is characteristic but they may not be present until age 4 or 5 years following the appearance of caf√©-au-lait spots. Some patients have patchy scalp hair loss. The facies bears some resemblance to the Noonan syndrome but usually without the short, webbed neck. Sensorineural hearing loss is found in 20% of individuals. Cardiac conduction defects, pulmonic stenosis, and hypertrophic cardiomyopathy are often (85%) present. Cognitive defects are present in 30% of patients and some individuals have been described as mentally retarded. Juvenile behavior may be evident in the presence of normal intelligence. Hypospadias, cryptorchidism, and gonadal infantilism have been seen in some patients. The ears are often malformed (87%). Thoracic skeletal anomalies have been described in 75% of patients. Although somatic growth is described as slow, short stature is present in less than half of patients.
Rare patients without lentigines are said to resemble the Noonan syndrome (163950) in appearance.