Williams syndrome in an adult.

We report a case of a diagnosis of Williams syndrome in a 57-year-old male referred for cardiac surgery with a presumptive diagnosis of aortic valvular stenosis and ascending aortic aneurysm, supravalvular stenosis being first suspected during surgery. Williams syndrome was subsequently confirmed via genetics testing. In patients presenting with an ascending aortic aneurysm, developmental delay, and with poorly visualized coronary arteries during angiography, the diagnosis of supravalvular aortic stenosis or Williams syndrome should be considered.