1. What is Inverse Allele Frequency?

The Inverse Allele Frequency (IF) is a simple mathematical transformation of allele frequency (F) that represents how rare an allele is in a population. It's calculated as the reciprocal of the allele frequency.

2. How Does the Calculator Work?

The calculator uses the inverse frequency formula:

Where:

• \( IF \) — Inverse frequency (dimensionless)
• \( F \) — Allele frequency (dimensionless, between 0 and 1)

Explanation: The inverse frequency gives higher values for rarer alleles. For example, an allele with frequency 0.01 (1%) has an inverse frequency of 100.

3. Importance of Inverse Frequency Calculation

Details: Inverse frequency is used in genetic studies to weight rare variants differently from common variants, particularly in association studies and polygenic risk score calculations.

4. Using the Calculator

Tips: Enter the allele frequency as a value between 0 and 1 (e.g., 0.01 for 1%). The frequency must be greater than 0 and less than or equal to 1.

5. Frequently Asked Questions (FAQ)

Q1: What does a high inverse frequency mean?
A: A high inverse frequency indicates a rare allele in the population. For example, IF=100 means the allele occurs in 1 in 100 individuals.

Q2: How is inverse frequency used in genetics?
A: It's often used to weight variants in genetic association studies, giving more weight to rare variants that might have larger effect sizes.

Q3: What's the range of possible inverse frequencies?
A: The minimum is 1 (for F=1, a fixed allele). There's no theoretical maximum, but practical values rarely exceed 10,000 (F=0.0001).

Q4: Can inverse frequency be calculated for allele frequencies of 0?
A: No, division by zero is undefined. The allele frequency must be greater than 0.

Q5: Is inverse frequency the same as odds?
A: No, inverse frequency is simply 1/F, while odds would be (1-F)/F for a binary allele.