Which genetic disorder causes mucus plugs in the lungs and digestive tract?

• A. Pneumonia
• B. Pleural Effusion
• C. Hemothorax
• D. Cystic Fibrosis

Answer: (D)

This question tests recognition of a genetic disorder that produces thick, sticky mucus affecting both the lungs and the digestive tract. In cystic fibrosis, mutations in the CFTR gene disrupt chloride transport and reduce water movement on mucosal surfaces, so mucus becomes dehydrated and highly viscous. In the lungs, this thick mucus blocks small airways, traps bacteria, and leads to chronic infections and bronchiectasis. In the digestive system, thick mucus can obstruct pancreatic ducts, causing pancreatic insufficiency and malabsorption of fats and fat-soluble vitamins. This combination of mucus plugging in the lungs and GI/pancreatic involvement is characteristic of cystic fibrosis. Other options describe acute or non-genetic conditions (infection, fluid in the pleural space, or bleeding) that don’t explain a congenital mucus-transport defect. CF is inherited in an autosomal recessive pattern and is typically investigated with sweat testing and genetic analysis.