A 4-year-old boy referred for a murmur has elfin facies, friendly extroverted behaviour, and a history of infantile hypercalcaemia. Echocardiography shows narrowing above the aortic valve with a Doppler gradient of 45 mmHg. Which structure is MOST likely responsible for his symptoms if untreated?

• A Diffuse narrowing of the ascending aorta at the sinotubular junction ✓
• B Discrete fibrous ring just below the aortic valve
• C Thickened bicuspid valve with fused commissure
• D Coarctation at the ductal insertion site

Explanation

Williams-Beuren syndrome (elastin gene deletion at 7q11.23) causes supravalvular aortic stenosis, an hourglass narrowing at the sinotubular junction above the valve, often with peripheral pulmonary artery stenosis. Subaortic membrane sits below the valve, bicuspid stenosis is at the valve level with an ejection click, and discrete coarctation is juxtaductal, so each distractor describes a different anatomical level of obstruction.

Reference: Nelson Textbook of Pediatrics, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.