Cystic fibrosis affects all system except –
**Core Concept**
Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene, leading to abnormal chloride transport across epithelial membranes. This results in thickened secretions in various organs, causing multiple systemic manifestations.
**Why the Correct Answer is Right**
The correct answer is related to the fact that cystic fibrosis primarily affects organs with exocrine secretions, such as the lungs, pancreas, liver, and intestines. The CFTR protein is a chloride channel that plays a crucial role in maintaining the balance of electrolytes and water in these secretory epithelia. In CF, the defective CFTR protein leads to dehydration of mucus, resulting in its thickening and plugging of airways, digestive tract, and other organs.
**Why Each Wrong Option is Incorrect**
**Option A:** Although the skin may exhibit manifestations of cystic fibrosis, such as thickened sweat, it is not an organ primarily affected by the disease. The correct answer is not about the skin.
**Option B:** The nervous system is not directly affected by cystic fibrosis, although patients may experience complications such as meconium ileus in the newborn period, which may require surgical intervention.
**Option C:** The cardiovascular system is not directly affected by cystic fibrosis, although patients may experience increased risk of pulmonary hypertension and heart failure due to chronic respiratory disease.
**Option D:** The musculoskeletal system is not directly affected by cystic fibrosis, although patients may experience muscle wasting and weakness due to malnutrition and chronic illness.
**Clinical Pearl / High-Yield Fact**
Remember the acronym "CF" as "Cystic Fibrosis" and also as "Chloride Fault," which represents the fundamental defect in chloride transport in this disease.
**Correct Answer: D. The musculoskeletal system.**