Two normal individuals have a child who has cystic fibrosis,an autosomal recessive disease.What were the chances of this happening? (Draw a Punnett square to help you determine the answer. )

Question

Quizplus · Accepted Answer

Since cystic fibrosis is an autosomal recessive disease, both parents would have to be carriers of the recessive gene in order for their child to inherit the disease. Using a Punnett square, the chances of two carriers having a child with cystic fibrosis is 1 in 4, or a 25% chance (represented by the ratio 1:4). Therefore, the best choice is A) 1:4 chance.

Two Normal Individuals Have a Child Who Has Cystic Fibrosis,an