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Getting more from less: Information yield increases from STR data when using TrueAllele® Technology

M. Legler, T. Nafziger, "Getting more from less: Information yield increases from STR data when using TrueAllele® Technology", Promega's Thirty Fourth International Symposium on Human Identification, Denver, CO, 20-Sep-2023.


Poster

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Abstract

As those in the criminal justice field become more aware of DNA evidence, crime labs are receiving an increased number of low level and touch samples. These types of samples prove challenging to interpret using manual methods. Toward this end, many DNA labs have started to use technology, such as probabilistic genotyping (PG) software, to assist in data interpretation. What impact does using a PG interpretation tool have for a typical lab?

The DNA lab of the Greenville County DPS Forensics Division started using the GlobalFiler™ STR kit in 2017. As they processed cases, they recorded, by case, the success rate when samples produced an interpretable result relevant to the case. During the period from 2017 to 2020, they had an initial quantitation threshold of 60 picograms (pg). The success rates of touch/ownership samples from guns/knives, clothing, cars, cartridge cases (fired and unfired), and other miscellaneous items were tracked.

The lab began to explore PG solutions in 2020 and chose to use TrueAllele® Technology. They internally validated TrueAllele for up to four unknown contributors, and began using this PG technology in casework in August 2020.

After the introduction of TrueAllele, the lab observed increases in success rates across sample types:

  • Guns/knives: 154% increase
  • Clothing: 87.9% increase
  • Cars: 437% increase
  • Cartridge cases (fired and unfired): 223% increase
  • Other miscellaneous items: 106% increase

In the nearly 3 years since deploying PG DNA interpretation, the Greenville lab continued to measure the success rate for sample amplification and interpretation. Using PG for low-level and complex mixture interpretation resulted in changes to the quantitation threshold and probative result recovery rates. This talk will summarize the Greenville DNA lab's journey and discuss their success and future plans.


Links


  • Promega's Thirty Fourth International Symposium on Human Identification - Site
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