Severely calcified valvular aortic stenosis firstly diagnosed in monozygotic male twins with suspected Williams-Beuren syndrome.

Williams-Beuren syndrome is a rare and usually sporadic genetic anomaly with an estimated frequency of 1:25,000, that also has cardiac defects due to the effect on the elastin locus of a deletion on the 7th chromosome. Identical twin boys presented with exercise-induced syncope. Echocardiographic examination revealed severe calcification at the aortic valves, mitral anterior leaflets, and mitral annuli in both cases. A basal interventricular septum was also involved in one case. Doppler evaluation demonstrated severe aortic stenosis with a peak gradient of 112 and 118 mmHg in both cases. Moderate mitral stenosis was also detected in one twin. We performed aortic mechanical valve replacement and dilated the aortic annulus with Nick's procedure and evaluated the diagnosis and therapy methods in light of the literature. As a result, we determined that these boys are the first monozygotic twins who were diagnosed during childhood.