[Cardiovascular dysplasia in Noonan's syndrome. Apropos of 64 cases]

The multiple malformation syndrome with characteristic facies described by Jacqueline Noonan in 1963 is one of the most commonly encountered syndromes in paediatric cardiology. The series presented here comprises 64 cases, almost a quarter of which were familial (6 families). The morphotype (Turner phenotype with hypertelorism) can easily be recognized, but the variations, progressivity and resemblance to some similar syndromes imply a detailed analysis of a wide range of discriminant features. Short stature and webbed neck are less frequent than in Turner's syndrome, while mental debility and, mostly, cardiovascular lesions are much more frequent (the latter are present in 50-60% of the cases). The most typical cardiovascular lesion is pulmonary valve stenosis with dysplastic leaflets, or "atypical pulmonary stenosis syndrome", characterized by a curious electrical axis and above all, by left ventricular myocardiopathy with very peculiar deformations at ventriculography and 2D-echocardiography. In our series, myocardiopathy was even more frequent than dysplastic pulmonary valve stenosis (71.8% versus 64%). The dissemination of dysplastic lesions must be emphasized. They involve the aorta much more often than is usually reported (one-third of the cases); lesions of the lymphatic system are less frequent but may be severe. Occasionally, entirely different heart diseases, such as Fallot's tetralogy, are encountered. Owing to the relationship between its lesions and those of other multiple malformation syndromes, notably those of the phakomatosis group, and to the possibility of borderline cases with these syndromes, or even with other dystrophies, such as Williams-Beuren dystrophia, the cardiovascular dysplasia of Noonan's syndrome must be classified within the vast group of histodysplasias which are embryonic diseases of the "layers" or "neuro-ecto-mesodermoses" of unknown genetic mechanism.