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Fold Change Equation:
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The conversion from log2 fold change (LFC) to fold change (FC) is a mathematical transformation commonly used in genomics and bioinformatics to express gene expression differences in a more intuitive linear scale rather than logarithmic scale.
The calculator uses the simple exponential equation:
Where:
Explanation: This conversion reverses the logarithmic transformation, returning the data to its original linear scale where values represent actual multiplicative changes.
Details: Converting log2 fold change back to fold change is essential for interpreting gene expression results in biological contexts, where fold changes of 2x, 3x, etc., are more meaningful than logarithmic values.
Tips: Enter the log2 fold change value. The calculator will compute and display the corresponding fold change value. Positive LFC values indicate up-regulation, negative values indicate down-regulation.
Q1: Why use log2 transformation in the first place?
A: Log2 transformation helps normalize data distribution, reduces the impact of extreme values, and makes fold changes symmetric around zero.
Q2: What does a fold change of 2 mean?
A: A fold change of 2 means the gene expression has doubled (2x increase), while a fold change of 0.5 means it has halved (2x decrease).
Q3: How do negative log2 values convert to fold change?
A: Negative log2 values convert to fold changes between 0 and 1. For example, LFC = -1 converts to FC = 0.5 (50% of original expression).
Q4: What's considered a significant fold change?
A: Typically, fold changes ≥2 (up-regulation) or ≤0.5 (down-regulation) are considered biologically significant, though this depends on the specific experiment and statistical thresholds.
Q5: Can this conversion be used for other logarithmic bases?
A: This specific formula is for log2. For other bases (e.g., natural log), different exponential formulas would be needed.