A newborn presents with hypocalcemic seizures, a ventricular septal defect, and absent thymic shadow on imaging. Fluorescence in situ hybridization shows a microdeletion on chromosome 22q11.2. The embryological defect responsible for this syndrome involves failure of development of which pharyngeal pouches?

• A 1st and 2nd pharyngeal pouches
• B 2nd and 3rd pharyngeal pouches
• C 3rd and 4th pharyngeal pouches ✓
• D 4th and 6th pharyngeal pouches

Explanation

DiGeorge syndrome (22q11.2 deletion) results from abnormal development of the 3rd and 4th pharyngeal pouches, causing thymic (T-cell deficiency), parathyroid (hypocalcemia), and conotruncal cardiac anomalies. The 1st and 2nd pouches form middle ear and palatine tonsil structures. The 4th and 6th pouches contribute to laryngeal cartilages, not the DiGeorge triad.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.