A 22-year-old man is admitted with his third episode of spontaneous pneumothorax. CT chest shows bilateral apical bullae. He is a tall, thin male with arm span exceeding height. Which syndrome should be suspected and what mutation is classically responsible?
- A Marfan syndrome; FBN1 (fibrillin-1) mutation ✓
- B Birt-Hogg-Dubé syndrome; FLCN (folliculin) mutation
- C Alpha-1 antitrypsin deficiency; SERPINA1 mutation
- D Lymphangioleiomyomatosis; TSC1/TSC2 mutation
Explanation
Recurrent spontaneous pneumothorax in a tall, thin young man with arm span > height is classic for Marfan syndrome, caused by mutations in FBN1 (fibrillin-1) on chromosome 15. Fibrillin-1 deficiency leads to defective elastic tissue in the lung, predisposing to subpleural bleb formation and pneumothorax. Birt-Hogg-Dubé syndrome (FLCN mutation) also causes recurrent pneumothorax but is associated with fibrofolliculomas and renal tumors. Alpha-1 antitrypsin deficiency causes pan-acinar emphysema, not bullous disease in the apices of young patients. LAM (TSC mutations) predominantly affects women.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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