A 6-year-old boy has chronic purulent rhinitis, recurrent otitis media, and bronchiectasis. Chest imaging shows dextrocardia with mirror-image reversal of thoracic and abdominal organs. The defect responsible for this combination is:

• A Mutation in the CFTR chloride channel
• B Alpha-1 antitrypsin deficiency
• C Defective dynein arm of ciliary microtubules ✓
• D Defect in the surfactant protein B gene

Explanation

Kartagener syndrome is the triad of sinusitis, bronchiectasis, and situs inversus caused by primary ciliary dyskinesia, classically due to absent or defective outer dynein arms of the 9 plus 2 axoneme. Immotile cilia impair mucociliary clearance and disrupt embryonic nodal cilia, producing situs inversus. CFTR mutation causes cystic fibrosis, which gives bronchiectasis but never situs inversus, making it the strongest distractor.

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.