Question

Sickle cell anemia is an inherited disease in which red blood cells become distorted and deprived of oxygen. A person with two sickle cell genes will have the​ disease, but a person with only one sickle cell gene will have a​ mild, non-fatal anemia called sickle cell trait. Using S to represent a healthy​ gene, and s the sickle cell​ gene, the table shows the four possibilities for the children of two Ss parents. Find the probability that these parents give birth to a child who has sickle cell anemia.

Answer 1

1/4 chance

Explanation:

Using the punnet square, you will find that there is a 1/4 chance the child will have no traits of sickle cell, 1/2 chance the child will have the sickle cell trait but no disease, and 1/4 chance the child will have sickle cell.

Answer 2

The probability that two parents with the genotype SS will give birth to a child with sickle cell anemia is 1/4 or 25%.

The probability that two parents with the genotype SS will give birth to a child with sickle cell anemia (genotype ss) can be determined using a Punnett square.

Since both parents have the genotype SS, their offspring will inherit one S allele from each parent.

When we cross the genotypes, we get the following possibilities:

1/4 chance of having a child with the genotype SS (healthy)

2/4 chance of having a child with the genotype Ss (carrier, but not affected by the disease)

1/4 chance of having a child with the genotype ss (sickle cell anemia)

Therefore, the probability that these parents give birth to a child with sickle cell anemia is 1/4 or 25%.