A neonate has cleft palate, hypocalcemia (tetany), absent thymus, and truncus arteriosus on echocardiography. The chromosomal abnormality most likely to be detected on FISH analysis is:
- A Deletion of chromosome 22q11.2 ✓
- B Deletion of chromosome 5p
- C Trisomy 18
- D Deletion of chromosome 15q11–13
Correct answer: A. Deletion of chromosome 22q11.2
Explanation
DiGeorge syndrome / 22q11.2 deletion syndrome (velocardiofacial syndrome) classically presents with the CATCH-22 mnemonic: Cardiac defects (conotruncal: truncus arteriosus, ToF, interrupted aortic arch), Abnormal facies, T-cell deficit (absent thymus → immunodeficiency), Cleft palate, Hypocalcemia (absent parathyroids). FISH for 22q11.2 is diagnostic. Chromosome 5p deletion causes Cri-du-Chat. Trisomy 18 features rocker-bottom feet and overlapping fingers. 15q11–13 deletion causes Prader-Willi or Angelman syndrome.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.