Sickle cell anemia is an inherited disease in humans which manifests itself in s

Question

Sickle cell anemia is an inherited disease in humans which manifests itself in severely inadequate supply of the oxygen throughout the body. The disease is caused by red blood cells containing only S-type hemoglobin. S-type hemoglobin is encoded by the Hbp allele of the hemoglobin- gene. Htps is recessive to the wild-type allele Hbm which encodes normal A-type hemoglobin and confers a healthy supply of oxygen in the body. Joshua is healthy, but his sister suffers from sickle cell anemia. Joshua's father also suffers from sickle cell anemia but his mother is healthy a. Determine and show the genotypes of Joshua, his mother, his father, and his sister If Joshua's parents have another child, what is the probability that this child will be affected by sickle cell anemia? b. If Joshua marries a healthy woman who is heterozygous for sickle cell anemia, what is the probability that their first child will suffer from the disease?

Explanation / Answer

This is case of sex linked(x-linked) dominant inheritance

In this case condition are

• affected males must come from affected mothers.

• affected female come from affected mother and fathers so all the daughters but none of the sons,of an affected father are affected.

A) joshua healthy,joshua mother healthy bt his sister are affected due to father affected. Bcoz of x-linked dominant case.

B) 50% or 1/2

Bcoz male probability 1/2 and female also 1/2

So affected all female so probability also 1/2

C) if jashua marry to a healthy women who is heterozygous for sickle cell anemia so mother affected chances is 1/2

So mother is heterozygous so chances is 1/4

And father chances is 1/2

So first child affected chances is 1/2*1/4= 1/8

So answer is 1/8

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