Question

Consider the following statements: Cystic fibrosis of the pancreas
1. Is an autosomal dominant disorder.
2. Is established by sweat sodium concentrations more than 80 mmol/L.
3. May produce neonatal small bowel obstruction.
4. Is associated with a dysfunction of all mucus secreting glands.
Which of these statements are correct?

• A. 2, 3 and 4
• B. 1, 3 and 4
• C. 1, 2 and 3
• D. 1, 2 and 4

Hint:

Remember cystic fibrosis is autosomal recessive, not dominant, even though its other features here are all true.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to check each of the four statements about cystic fibrosis of the pancreas and identify which combination is correct.

Step 2: Key Formula or Approach:
Cystic fibrosis is caused by a defect in the CFTR chloride channel gene, and this single defect explains its inheritance pattern, its effect on sweat glands, its effect on the bowel in newborns, and its effect on mucus glands throughout the body.

Step 3: Detailed Explanation:
Statement 1 is false, since cystic fibrosis is actually inherited as an autosomal recessive disorder, requiring two defective copies of the CFTR gene, not an autosomal dominant one.
Statement 2 is true, since the sweat chloride test, and the associated elevated sweat sodium level typically above 60 to 80 mmol/L depending on the lab's cutoff, is the classic diagnostic test for cystic fibrosis, reflecting the defective chloride channel's effect on sweat gland function.
Statement 3 is true, since cystic fibrosis can cause thick, inspissated meconium in the newborn bowel, leading to meconium ileus, a form of neonatal small bowel obstruction.
Statement 4 is true, since the underlying CFTR defect affects chloride transport in essentially all exocrine mucus secreting glands throughout the body, including the pancreas, lungs, intestine, and reproductive tract, causing thick, viscous secretions everywhere.

Step 4: Final Answer:
So statements 2, 3, and 4 are correct, while statement 1 is false, since cystic fibrosis is autosomal recessive, not dominant.