Cornelius and Janelle sought genetic counseling because of concern that they might have children with sickle-cell disease. The counselor determined they each have one recessive allele for sickle-cells and one dominant allele for healthy blood cells. The counselor would tell them that they have a
A) 100% chance of having a child with sickle-cell disease.
B) 25% chance of having a child with sickle-cell disease and a 50% chance of having a child with sickle-cell trait.
C) 25% chance of having a child with sickle-cell trait and a 50% chance of having a child with sickle-cell disease.
D) 75% chance of having a child with sickle-cell disease.

Question

Quizplus · Accepted Answer

Cornelius and Janelle each have one recessive allele for sickle-cell disease and one dominant allele for healthy blood cells. This means that there is a 25% chance of both parents passing on the recessive sickle-cell allele to their child, resulting in sickle-cell disease. There is also a 50% chance that the child will inherit one dominant healthy allele and one recessive sickle-cell allele, resulting in sickle-cell trait. Therefore, the correct answer is B, 25% chance of having a child with sickle-cell disease and a 50% chance of having a child with sickle-cell trait.

Cornelius and Janelle Sought Genetic Counseling Because of Concern That