Cystic Fibrosis: Organs Involved
Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene. This defect impairs chloride ion transport across epithelial cell membranes, causing exocrine glands throughout the body to secrete abnormally thick, sticky mucus. The organs most affected are those lined by mucus-secreting epithelium — the lungs, pancreas, and liver — not the kidneys.
Analysis of Each Organ
- 1. Lungs: Thick mucus obstructs the bronchi and bronchioles, impairing mucociliary clearance. This leads to chronic respiratory infections, bronchiectasis, and progressive lung damage — the leading cause of morbidity and mortality in CF. Affected.
- 2. Liver: Thickened bile obstructs the intrahepatic bile ducts, which can lead to focal biliary cirrhosis and, in some patients, progress to multilobular cirrhosis and portal hypertension. Affected.
- 3. Pancreas: Viscous secretions block the pancreatic ducts, preventing digestive enzymes from reaching the duodenum. This causes exocrine pancreatic insufficiency (malabsorption, steatorrhea) and, over time, can damage the islets, leading to CF-related diabetes. Affected.
- 4. Kidney: The kidneys are not lined by the exocrine mucus-secreting epithelium primarily disrupted in CF and are not considered a classically affected organ in the disease. Not affected as part of the core CF pathology.
Why the Other Options Are Incorrect
- 1, 3 and 4 — incorrectly includes the kidney while omitting the liver, which is a well-documented site of CF pathology.
- 2, 3 and 4 — omits the lungs, the single most clinically significant organ affected in CF, and wrongly includes the kidney.
- 1, 2 and 4 — correctly includes lungs and liver but wrongly includes the kidney instead of the pancreas, which is a core affected organ.
Conclusion
Cystic fibrosis classically involves the Lungs (1), Liver (2), and Pancreas (3) due to defective CFTR-mediated mucus clearance in these exocrine organs. The kidney is not a primary target organ in this disease. Hence, the correct answer is 1, 2 and 3.
