In a village if the proportion of individuals who have sickl

In a village, if the proportion of individuals who have sickle-cell disease is 0.10, and the population is assumed to be at Hardy-Weinberg equilibrium, what is the expected frequency of the HbS allele? (Hint: What is the genotype of people with sickle-cell disease, and how is that genotype represented in the Hardy-Weinberg equation?)

Solution

Answer:

Let the dominant allele be HbA and the recessive allele be HbS. For sickle cell disease to occur, the genotype should be HbS.

So, HbA/HbA (p²) = Normal, HbA/HbS (2pq) = Heterozygous, HbS/HbS (q²) = sickle cell disease

q² = 0.1

q = 0.316. This is the frequency of the HbS allele in the population.