CpG Islands Finder

Identify CpG islands in DNA sequences using sliding window analysis. Find potential gene regulatory regions and promoter elements.

Analysis Parameters
Window Size 200 bp
Minimum Obs/Exp Ratio 0.60
Minimum GC Content 50%
Minimum Island Length 200 bp
Step Size 1 bp
Gap Tolerance 50 bp
CpG Islands Map

Sequence Overview

Blue-green blocks represent CpG islands along the sequence

Island #StartEndLengthObs/ExpGC%CpG Count

What are CpG Islands?

CpG islands are DNA regions with high frequency of CpG dinucleotides. They're often found near gene promoters and are important for gene regulation through DNA methylation patterns.

How to Use This Tool

Analyze CpG islands in 4 steps:

  1. Paste your DNA sequence
  2. Adjust analysis parameters
  3. View islands on sequence map
  4. Download detailed results

When to Use

This tool is essential for:

  • Gene promoter analysis
  • Methylation site prediction
  • Regulatory region identification
  • Epigenetic research planning

Example Input

Sample DNA sequence with CpG islands:

CGCGCGCGCGCGCGATCGATCGCGCGCGCGCG...

Try the Example button for a real promoter sequence

Example Output

Detailed island characteristics:

Island 1: 150-350 bp
Length: 201 bp
Obs/Exp: 0.75
GC%: 65%

FAQ

Q: What does Obs/Exp ratio mean?
A: Observed vs Expected CpG frequency. Values >0.6 indicate CpG enrichment.

Q: Why is GC content important?
A: CpG islands typically have high GC content (>50%) due to CpG enrichment.