What is cystic fibrosis?

What is the risk of a child being born with cystic fibrosis?

• If a mother is a heterozygous carrier of the cystic fibrosis allele and her male partner is homozygous for healthy (non-cystic fibrosis) alleles. What are the chances that their first child will have the disease cystic fibrosis? Biology question for school trying to check my answer.

• Answer:

  since cystic fibrosis is a recessive disease, there is no chance that the child will have cystic fibrosis. Since the father is homozygous for the healthy allele, and the mother is only a carrier, there is a 1/2 chance the child will be a carrier and a 1/2 chance the child will be homozygous for the healthy allele. The only way the child could have cystic fibrosis is if both of the parents had at least one cystic fibrosis allele.