Question

Which type of mutation causes cystic fibrosis?

Answer 1

Most commonly by a 3‑base pair (in‑frame) deletion in the CFTR gene — the ΔF508 mutation that removes phenylalanine at position 508. This causes abnormal CFTR folding/processing (a class II loss‑of‑function mutation). CF is inherited autosomal recessively; other CFTR mutations (nonsense, missense, splice, etc.) can also cause the disease.