is cystic fibrosis a dominant or recessive disorder
Cystic fibrosis. Cystic fibrosis (CF) is caused by a recessive allele. You need to inherit two copies of the faulty allele to have CF. If you just have one copy of the faulty allele, you are a carrier but have no symptoms. If two carriers have a child between them, there is a one in four chance of that child having the disorder.