IUPAC Ambiguity Code Expander

Expand degenerate nucleotide codes (R, Y, N, W, S, K, M, B, D, H, V) into all possible sequence combinations for primer analysis

What is IUPAC Ambiguity Code Expander?

The IUPAC Ambiguity Code Expander is a bioinformatics tool that converts degenerate DNA/RNA sequences containing IUPAC ambiguity codes into all possible non-degenerate sequence combinations. IUPAC codes like R (A or G), Y (C or T), and N (any nucleotide) represent multiple possible bases at a single position, commonly used in primer design and motif searching.

How to Use This IUPAC Expander

Quick guide to expand your sequences:

  1. Paste your DNA/RNA sequence containing IUPAC codes (R, Y, N, W, S, K, M, B, D, H, V)
  2. View all possible sequence combinations instantly
  3. Review statistics about combinations and ambiguous positions
  4. Download or copy expanded sequences for further analysis

When to Use

This tool is essential when you need to:

  • Analyze degenerate primers and their binding specificity
  • Enumerate all possible sequences from ambiguous motifs
  • Validate primer design with wobble positions
  • Generate all variants of a consensus sequence
  • Study binding site permutations for regulatory elements

IUPAC Codes Reference

Standard ambiguity codes:

R = A or G (puRine)
Y = C or T (pYrimidine)
S = G or C (Strong)
W = A or T (Weak)
K = G or T (Keto)
M = A or C (aMino)
B = C, G, or T (not A)
D = A, G, or T (not C)
H = A, C, or T (not G)
V = A, C, or G (not T)
N = A, C, G, or T (any)

Example Input and Output

Input with IUPAC codes:

ATGCRN

Output (8 sequences):

ATGCAA
ATGCAC
ATGCAG
ATGCAT
ATGCGA
ATGCGC
ATGCGG
ATGCGT

FAQ

Q: How many sequences will be generated?
A: The number depends on ambiguity codes. For example, "ATN" generates 4 sequences (N=4 options), while "ATRYN" generates 8 (R=2, Y=2, N=4: 2×2×4=16, but simplified to unique combinations).

Q: What's the maximum number of combinations?
A: For practical purposes, the tool limits output to 10,000 sequences. Be cautious with multiple N's (N×N×N grows exponentially).

Q: Can I use lowercase sequences?
A: Yes, the tool automatically converts sequences to uppercase.