Galactosemia is inherited as a homozygous recessive trait (i. e., gg). You have sampled a population in which 36% of people have galactosemia.

a. What is the frequency of the g allele?

b. What is the frequency of the G allele?

c. What is the frequency of the GG and Gg genotypes?

a. The frequency of the g allele = 0.6

b. The frequency of the G allele = 0.4

c. The frequency of the GG genotype = 0.16 or 16%

The frequency of Gg genotype = 0.48 or 48%

Explanation:

According to the given information, the disorder is homozygous recessive trait. The frequency of the homozygous recessive genotype (gg) in the population (q^2) = 36% or 0.36

Therefore, the frequency of the recessive allele "g" (q) = square root of 0.36 = 0.6

Since p + q = 1

Therefore p = 1-q = 1-0.6 = 0.4

The frequency of the dominant allele "G" (p) = 0.4

The frequency of the homozygous dominant genotype GG = p^2 = 0.4 x 0.4 = 0.16 or 16%

The frequency of heterozygous dominant genotype Gg = 2pq = 2 x 0.6 x 0.4 = 0.48 = 48%