METHODS Patients Eighty four white Italian patients were recruited. Informed consent and family history were obtained from all subjects and their parents. Patients were ascertained by clinical geneticists and paediatric cardiologists. Noonan syndrome was diagnosed on the basis of the cardinal features delineated by Allanson1—in particular short stature, congenital heart defects, broad or webbed neck, chest deformity, developmental delay of variable degree, cryptorchidism, and characteristic facies. For diagnosis of ML/LS, the presence of lentiginosis and café au lait spots was required, in combination with at least three of the cardinal features outlined by Voron et al. 16 Clinical assessment included family history, complete physical evaluation of dysmorphisms and malformations, anthropometric measurements, renal ultrasonography, and radiological studies. Standard karyotyping was normal in all patients.

Cardiac evaluation in all patients included preoperative chest x ray, ECG, and cross sectional and colour Doppler echocardiography. Pulmonary stenosis, pulmonary valve leaflet dysplasia, and hypertrophic cardiomyopathy were assessed using classical echocardiographic criteria. 2 Cardiac catheterisation with angiocardiography was undertaken in 51 patients as an aid to preoperative assessment, to attempt pulmonary valve dilatation, or to demonstrate left ventricular shape. The cardiac diagnoses were confirmed during cardiac surgery in 32 subjects.