Cystic fibrosis is an autosomal recessive condition.If the parents of a boy with cystic fibrosis have two more children,what is the probability that both of these children will be unaffected?
A)1/16
B)3/16
C)4/16
D)9/16
E)16/16

Question

Quizplus · Accepted Answer

In an autosomal recessive condition like cystic fibrosis, both parents must be carriers (heterozygous) if they have an affected child. The chance of a child being unaffected (not having cystic fibrosis) is 3/4 (75%) for each pregnancy. Therefore, the probability that both children will be unaffected is (3/4) * (3/4) = 9/16.

Cystic Fibrosis Is an Autosomal Recessive Condition