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STR Data Analysis and Interpretation for Forensic Analysts

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Image of peaks and bands
National Institute of Justice (NIJ) (see reuse policy).

Data produced in the separation and characterization of amplified DNA is displayed as:

  • Peaks (capillary electrophoresis)
  • Bands (slab gel electrophoresis)

The DNA fragments are sized, which includes an indirect assessment of quantity present (peak area/height or band density), and genotypes are assigned. The conversion of sized DNA fragments to genotypes is the standardization between all forensic DNA laboratories for comparing data and is essential for laboratories utilizing CODIS to compare profiles. 

The steps for converting fluorescent data/peaks into allele calls are shown below with the corresponding software noted to the right of the specific steps.01

Diagram of steps for converting fluorescent data/peaks into allele calls
National Institute of Justice (NIJ) (see reuse policy).

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