[Williams-Beuren facies with mental retardation and tetralogy of Fallot]

The "elfin facies", described by Williams and Beuren, is usually associated, beside mental retardation, with a supravalvular aortic stenosis and, more broadly, with multiple arterial stenoses. Other types of cardiac defects were described in this context, but the case reported by the authors is the first one with a tetralogy of Fallot. The hypothesis of widerspread histodysplastic lesions is discussed: the process may be early enough to alter the morphogenesis of the cardiac conus and to produce, more lately, the classical stenotic lesions of the arterial wall.