Question

If 15% of the population carries at least one copy of the recessive allele: What is the predicted frequency of individuals in the population that express the dominant phenotype? What is the predicted frequency of individuals in the population that express the recessive phenotype?

Answer 1

According to Hardy-Weinberg equations:

p + q = 1

p² + 2pq + q² = 1

where p - frequency of the dominant allele, q - frequency of the recessive allele, p² - frequency of homozygous dominant genotype, 2pq - frequency of heterozygous genotype, q² - frequency of recessive genotype.

As 15% of the population carries a copy of the recessive allele (q=0.15), 100% - 15% = 85% of the population carries a copy of the dominant allele (p=0.85).

As a result, the predicted frequency of individuals in the population that express the dominant phenotype equals p² + 2pq = 0.85² + 2 × 0.85 × 0.15 = 0.9775 = 0.98

The predicted frequency of individuals in the population that express the recessive phenotype equals q² = 0.15² = 0.0225 = 0.02.

Answer: 0.98 and 0.02