Cystic fibrosis is caused by a recessive gene. If C = normal and c = cystic fibrosis, how can a child with cystic fibrosis have two parents that do not have cystic fibrosis?

Question

Quizplus · Accepted Answer

Both parents must be carriers of the recessive cystic fibrosis gene (Cc) but do not express the disease themselves. When they have children, there is a 25% chance that both parents will pass on the recessive gene and the child will have cystic fibrosis (cc). The child must inherit one recessive gene from each parent, resulting in the genotype of cc.

Cystic Fibrosis Is Caused by a Recessive Gene