Two parents heterozygous for cystic fibrosis have a child with the disease. The parents are expecting a second child. What is the probability that the second child will also have cystic fibrosis?
A) 100% probability
B) 75% probability
C) 50% probability
D) 25% probability
E) 0% probability

Question

Quizplus · Accepted Answer

Cystic fibrosis is an autosomal recessive disorder. When both parents are heterozygous (carriers), each child has a 25% chance of inheriting two recessive alleles and having the disease.

Two Parents Heterozygous for Cystic Fibrosis Have a Child with the Disease