A 5-year-old child is evaluated for mild intellectual disability. She is overly friendly and talks to strangers without hesitation. Physical examination reveals a short nose with a broad tip, long philtrum, full lips, and a hoarse voice. Cardiac auscultation reveals a systolic ejection murmur best heard at the right upper sternal border radiating to the neck. Which of the following genetic abnormalities is most likely responsible?

• A Microdeletion on chromosome 7q11.23 ✓
• B Trinucleotide repeat expansion on Xq27.3
• C Microdeletion on chromosome 15q11-q13
• D Microdeletion on chromosome 22q11.2

Explanation

Williams syndrome is caused by a microdeletion on chromosome 7q11.23. The classic presentation includes an overly friendly personality, intellectual disability, characteristic elfin facies (short nose, broad tip, long philtrum, full lips), and supravalvular aortic stenosis, which produces a systolic ejection murmur radiating to the neck. Option B causes Fragile X syndrome. Option C causes Prader-Willi or Angelman syndrome depending on the parent of origin. Option D causes DiGeorge syndrome.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.