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STRmix™ EMPOWERING FORENSIC SCIENCE

How

How does FaSTR™ DNA work?

DNA analysis is a process of identifying alleles. The alleles appear as peaks in an electropherogram (EPG) and are identified from their locations within the EPG. The locations are determined using internal size standards and ‘ladders’.

FaSTR™ DNA

Contains the size-standard and ladder data for commonly-available testing kits. Additional kits and size standards can easily be added by importing panel, bin, and size standard information, or by manual entry.

Based on an adaptation of the methods implemented in OSIRIS[1], FaSTR™ DNA applies a set of fully configurable rules to identify and label alleles and reject artefacts within the EPGs of test samples.

The Analysis Process

EPGs are produced by genetic analysers in the form of .fsa, .hid or .promega data files. FaSTR™ DNA analyses EPG data in steps by:

  1. Dynamic baselining of the EPG data.
  2. Detection and assignment of size-standard peaks for the accurate sizing of peaks in the allelic ladder and test sample.
  3. Size alignment of peaks detected in the allelic ladder with peaks detected in the test sample to apply allele calls.
  4. Optionally applying a set of analysis rules to distinguish artefactual from allelic peaks.
  5. Optionally carrying out NoC estimation.
  6. Optionally carrying out sample to sample or sample to database comparison checks.
  7. Carrying out full concordance testing on positive and negative controls, including quality marker checks.
  8. Exporting the results as configurable outputs.
  9. Carrying out a project review to compare two analysed projects and resolve conflicts to create a final reviewed project.

 [1]  R.M. Goor, L. Forman Neall, D. Hoffman, S.T. Sherry, Mathematical approach to analysis of multiplex DNA profiles, Bull Math Biol 73(8) (2011) 1909-1931

Outputs

FaSTR™ DNA displays the results of its analysis (the ‘DNA profile’), as a labelled EPG and as a table of loci and peak designations.  With FaSTR™ DNA you can:

  • Easily print EPGs and include snapshots of areas of interest.
  • Easily print a report of changes made to peaks during analysis.
  • Export analysed data to STRmix™, the supplied CODIS tool or a data table.
  • Save the analysis as a ‘project’ for future reference.

Configuration parameters

The analysis settings can be general or specific to each STR kit type and locus. FaSTR™ DNA contains easily customisable default kits and methods. You can also create (and save) customised sets of parameters appropriate to different types of DNA samples (e.g. single-source samples and crime-scene samples).