A 3-year-old boy with a history of infantile hypercalcaemia has elfin facies, cheerful personality, and developmental delay. Examination reveals a harsh ejection systolic murmur at the right upper sternal border radiating to the neck. Echocardiography shows narrowing above the sinuses of Valsalva with a gradient of 60 mmHg. The MOST likely diagnosis is:

• A Coarctation of the aorta
• B Hypertrophic obstructive cardiomyopathy
• C Bicuspid aortic valve with valvar stenosis
• D Supravalvar aortic stenosis in Williams syndrome ✓

Explanation

Williams syndrome, caused by a microdeletion of the elastin gene (ELN) on chromosome 7q11.23, produces elfin facies, infantile hypercalcaemia, cognitive-behavioural phenotype, and peripheral pulmonary stenosis with supravalvar aortic stenosis. The narrowing sits above the sinuses of Valsalva rather than at the valve, distinguishing it from bicuspid aortic stenosis. Hypertrophic cardiomyopathy shows dynamic LV outflow obstruction with asymmetric septal hypertrophy, not supravalvar narrowing.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.