Cystic fibrosis (CF)is a Mendelian disorder in the human population that is inherited as a recessive. Two normal parents have two children with CF. The probability of their next child being normal for this characteristic is which of the following?

Question

Quizplus · Accepted Answer

Since CF is inherited as a recessive trait, both parents must be carriers of the CF gene (heterozygous) and have a 25% chance of having a child with CF (homozygous recessive) with each pregnancy. The probability of having a normal child (homozygous dominant) is 25% or 1/4. Therefore, the answer is C) 1/4.

Cystic Fibrosis (CF)is a Mendelian Disorder in the Human Population