1. What is the Recessive Allele Frequency Equation?

The recessive allele frequency equation estimates the frequency of a recessive allele in a population based on the incidence of the trait in females. This is particularly useful in X-linked recessive disorders where males are hemizygous for the X chromosome.

2. How Does the Calculator Work?

The calculator uses the recessive allele frequency equation:

Where:

• \( F \) — Frequency of recessive allele (dimensionless)
• \( I_f \) — Incidence of the trait in females (dimensionless)

Explanation: The equation assumes Hardy-Weinberg equilibrium and that the trait is X-linked recessive. The square root of the female incidence gives the allele frequency.

3. Importance of Allele Frequency Calculation

Details: Calculating allele frequencies is fundamental in population genetics, helping to understand disease prevalence, genetic counseling, and evolutionary biology.

4. Using the Calculator

Tips: Enter the incidence of the trait in females as a decimal between 0 and 1 (e.g., 0.0025 for 0.25% incidence).

5. Frequently Asked Questions (FAQ)

Q1: Why is this specific to females?
A: For X-linked recessive traits, females need two copies of the allele to express the trait, while males only need one. This makes female incidence particularly informative.

Q2: What assumptions does this calculation make?
A: It assumes Hardy-Weinberg equilibrium - random mating, no selection, no mutation, no migration, and large population size.

Q3: How does this differ from autosomal recessive calculations?
A: For autosomal recessive traits, the frequency would be the square root of the total incidence (not sex-specific).

Q4: What are typical values for recessive allele frequencies?
A: Most deleterious recessive alleles have frequencies below 0.01 in populations, though this varies by specific condition and population.

Q5: Can this be used for carrier frequency estimation?
A: For X-linked traits, female carrier frequency is approximately 2F(1-F) under Hardy-Weinberg assumptions.