[Noonan's syndrome and its cardiovascular dysplasia. Apropos of 64 cases].

The multiple malformation syndrome described by Jacqueline Noonan in 1963 is one of the most commonly encountered syndromes in pediatric cardiology. The series presented here comprises 64 cases, 20% of which were familial. The morphotype can easily be recognized, but the variations and changes with age imply a detailed analysis of a wide range of discriminatory features. Cardiovascular lesions are very common and very specific, diffuse but above all characterized by "atypical" pulmonary stenosis, with dysplastic valves and a cardiomyopathy of the left ventricle, which is very particular, but also encountered in other polymalformation syndromes. Aortic lesions and dysplasia of other valves are not infrequent. The genetic mechanism is as yet unknown; at present, only certain hypotheses can be proposed.