Chromosomal abnormalities · USMLE Step 1

Microarray testing on a child with intellectual disability and elfin facies reveals a deletion on chromosome 7q11.23. Which condition is this?

  1. DiGeorge syndrome
  2. Prader-Willi syndrome
  3. Williams syndrome
  4. Angelman syndrome
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Correct answer: Williams syndrome

Williams syndrome results from a microdeletion on chromosome 7q11.23, affecting elastin. Elfin facies and cognitive deficits are characteristic. The other disorders involve different chromosomal loci.

Difficulty: Medium Question 6 of 20

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