A 4-year-old boy with an 'elfin' face, friendly extroverted personality, and a history of infantile hypercalcemia has an ejection systolic murmur at the right upper sternal border radiating to the neck. The genetic defect underlying his cardiac lesion is:

• A Deletion of 22q11.2 affecting TBX1
• B Deletion of 5p15 (cri du chat region)
• C Mutation of the elastin gene at 7q11.23 ✓
• D Trisomy 21 affecting chromosome 21q

Explanation

Williams syndrome combines elfin facies, hypercalcemia, and supravalvular aortic stenosis, caused by a microdeletion at 7q11.23 that includes one copy of the elastin (ELN) gene. Elastin haploinsufficiency produces the arteriopathy. The 22q11.2 deletion causes truncus arteriosus and interrupted aortic arch in DiGeorge syndrome, which lacks the facial and metabolic features described here.

Reference: Park's Pediatric Cardiology for Practitioners, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.