MRCP2-4414

A young couple, Mr and Mrs Y, seek your advice. Mrs Y is currently six weeks pregnant. Mr Y’s sister and her partner had a child with cystic fibrosis. After being screened, Mr Y was found to carry the DF508 mutation for cystic fibrosis. Mrs Y is hesitant to undergo testing. Given that the gene frequency for this mutation in the general population is 1/20, what is the likelihood of their child having cystic fibrosis?