 Elastin, which is part of the extracellular matrix, controls proliferation of vascular smooth muscle cells VSMCs and stabilizes arterial structure. Loss of elastin gene in WBS patients has been claimed to provide a biological basis for the abnormal elastic fibre properties leading to cardiovascular abnormalities like supravalvular aortic stenosis SVAS, hypertension, arteriosclerosis and stenosis in more than 50 of WBS children. 