Which genetic disorder causes thick, sticky mucus that builds up in the lungs and digestive tract?

• A. Chronic Obstructive Pulmonary Disease
• B. Cystic Fibrosis
• C. Pneumothorax
• D. Pleural Effusion

Answer: (B)

Thick, sticky mucus in both the lungs and digestive tract points to cystic fibrosis, a genetic disorder caused by mutations in the CFTR chloride channel. When this channel doesn’t function properly, chloride (and water) movement across epithelial surfaces is reduced. The result is dehydrated, very thick mucus. In the airways, this mucus plugs small passages, impairs clearance of bacteria, and leads to recurrent lung infections and progressive airway damage. In the digestive system, blocked pancreatic ducts prevent digestive enzymes from reaching the gut, causing malabsorption and poor weight gain. Additional clues can include salty skin and a positive sweat test.

This pattern is distinct from the other conditions listed. COPD is typically due to smoking and aging with chronic airway obstruction rather than a congenital mucus problem affecting both lungs and the digestive tract. Pneumothorax is air in the pleural space causing lung collapse, not mucus buildup. Pleural effusion involves fluid accumulating in the pleural space, again not the thick mucus distribution seen in CF.