If Emily's parents decided to have another child, what would the genetic counselors have told them about their probability of having a second child with CF.

The counselors would explain in the simplest form possible their chances of having a second child with Cystic fibrosis (CF)

Explanation:

Since Emily's parents are CF carriers, the chances are:

25% (1 in 4) the child will have CF

50% (1 in 2) the child will be a carrier but will not have CF

25% (1 in 4) the child will not be a carrier of the gene and will not have CF

Also people with CF (Emily's parents) can also pass copies of their CF gene mutations to their children.

Put simply, If someone with CF has a child with a CF carrier, probability are:

50% (1 in 2) the child will be a carrier but will not have CF

50% (1 in 2) the child will have CF

Positive carrier test result for CF means that a person has one mutation of the CFTR gene.

Important to Note that:

A positive result is more than 99 percent accurate. And a negative carrier test result is not too accurate.