A child with Williams syndrome presents with short stature, elfin facies, gregarious personality, and hypercalcemia in infancy. On echocardiography, the most characteristic cardiac lesion expected is:

• A Ventricular septal defect
• B Pulmonary valve stenosis
• C Supravalvular aortic stenosis ✓
• D Atrioventricular septal defect

Explanation

Williams syndrome (microdeletion of chromosome 7q11.23 including the ELN gene encoding elastin) is characterized by supravalvular aortic stenosis (SVAS) in approximately 70% of cases, due to elastin haploinsufficiency causing arterial wall thickening. The elfin facies, cocktail party personality, intellectual disability and infantile hypercalcemia are hallmarks. AV septal defects are characteristic of Down syndrome; pulmonary stenosis occurs in Noonan and Alagille syndromes; VSDs are the most common CHD in general but not specific to Williams.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.