4. In areas of sub-Saharan Africa, equilibrium frequencies of the HbS allele rea

Question

4. In areas of sub-Saharan Africa, equilibrium frequencies of the HbS allele reach as
high as 0.2, this despite the fact that when homozygous, individuals suffer severe
anemia, and most die as young children.

a. Explain why this allele is maintained at such high frequency in this area.

b. Assuming the fitness of the HbS/HbS homozygotes is 0, what is the expected
relative fitness of the Hb+/Hb+ homozygotes at equilibrium?

c. What would you predict to be the equilibrium frequency of the HbS allele in the
United States? (assume a mutation rate of 1 x 10-7, and that heterozygotes have the
same fitness as the Hb+/Hb+ homozygotes).

d. HbS allele frequencies are not at this equilibrium in African American populations
in the United States, why?

Explanation / Answer

In areas of sub-Saharan Africa, equilibrium frequencies of the HbS allele reach as
high as 0.2, this despite the fact that when homozygous, individuals suffer severe
anemia, and most die as young children.
a. Explain why this allele is maintained at such high frequency in this area.

because of heterozygotic advantage of HbA/HbS IN MALARIA ENDEMIC AREA IN AFRICA ,IT IS maintained at such high frequency in this area.

b.Assuming the fitness of the HbS/HbS homozygotes is 0, what is the expected
relative fitness of the Hb+/Hb+ homozygotes at equilibrium?

Hb+/Hb+ homozygotes--------NORMAL FITNESS VALUE IS ONE

c. What would you predict to be the equilibrium frequency of the HbS allele in the
United States? (assume a mutation rate of 1 x 10-7, and that heterozygotes have the
same fitness as the Hb+/Hb+ homozygotes).

HbS allele--IS LESS

d.HbS allele frequencies are not at this equilibrium in African American populations
in the United States, why?

LACK OF ENDEMIC DISEASE LIKE MALARIA ,

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