The BiasAway software tool is introduced to generate nucleotide composition-matched DNA sequences. It is available as open source code from bitbucket.

The tool provides users with four approaches to generate synthetic or genomic background sequences matching mono- or k-mer composition of user-provided foreground sequences:

  1. synthetic k-mer shuffled sequences
  2. synthetic k-mer shuffled sequences in a sliding window
  3. genomic mononucleotide distribution matched sequences
  4. genomic mononucleotide distribution within a sliding window matched sequences

The 1st approach shuffles each user-provided sequences independently by preserving the k-mer composition of the input sequences. The 2nd approach applies the same method as the 1st approach but within a sliding window along the user-provided sequences. For the 3rd and 4th approaches, the background sequences are selected from a pool of provided genomic sequences to match the distribution of mononucleotide for each target sequence. The 4th approach considers the mean and standard deviation of %GC computed within the sliding window along the user-provided sequences to match as closely as possible the distribution for each user-provided sequence.

The approaches based on a sliding window were considered because due to evolutionary changes such as insertion of repetitive sequences, local rearrangements, or biochemical missteps, the target sequences may have sub-regions of distinct nucleotide composition.