An inter-laboratory study of DNA-based identity, parentage and species testing in animal forensic genetics

Abstract

The probative value of animal forensic genetic evidence relies on laboratory accuracy and reliability. Inter-laboratory comparisons allow laboratories to evaluate their performance on specific tests and analyses and to continue to monitor their output. The International Society for Animal Genetics (ISAG) administered animal forensic comparison tests (AFCTs) in 2016 and 2018 to assess the limitations and capabilities of laboratories offering forensic identification, parentage and species determination services. The AFCTs revealed that analyses of low DNA template concentrations (≤300 pg/µL) constitute a significant challenge that has prevented many laboratories from reporting correct identification and parentage results. Moreover, a lack of familiarity with species testing protocols, interpretation guidelines and representative databases prevented over a quarter of the participating laboratories from submitting correct species determination results. Several laboratories showed improvement in their genotyping accuracy over time. However, the use of forensically validated standards, such as a standard forensic short tandem repeat (STR) kit, preferably with an allelic ladder, and stricter guidelines for STR typing, may have prevented some common issues from occurring, such as genotyping inaccuracies, missing data, elevated stutter products and loading errors. The AFCTs underscore the importance of conducting routine forensic comparison tests to allow laboratories to compare results from each other. Laboratories should keep improving their scientific and technical capabilities and continuously evaluate their personnel’s proficiency in critical techniques such as low copy number (LCN) analysis and species testing. Although this is the first time that the ISAG has conducted comparison tests for forensic testing, findings from these AFCTs may serve as the foundation for continuous improvements of the overall quality of animal forensic genetic testing.

Key points

• Comparison tests allow laboratories to evaluate their analyses for accuracy and reliability.

• Two forensic identification, parentage and species determination comparison tests were performed.

• The study showed that the LCN DNA analysis represented a significant challenge to most laboratories.

• Lacking familiarity with species tests curbed most laboratories from reporting accurately.

• A reliance on forensically validated testing standards may have prevented some of the common errors.

Keywords:

• Forensic sciences
• forensic genetics
• comparison test
• forensic DNA analysis
• individual identification
• parentage test
• species test

Acknowledgements

We are grateful to Christopher C. Adams of Thermo Fisher Scientific for providing the Canine Genotypes™ Panels 1.1 and 2.1 Kit. We thank the members of ISAG’s Animal Forensic Genetics Standing Committee for supporting and facilitating the 2016 and 2018 AFCTs.

Authors’ contributions

All authors carried out the genetic studies, conceived of the study, and participated in its design; Sreetharan Kanthaswamy, Luis Cancela and Guillermo Giovambattista performed the statistical analysis; Sreetharan Kanthaswamy and Guillermo Giovambattista drafted the manuscript; and all authors contributed to the final text and approved it.

Compliance with ethical standards

All applicable international, national and/or institutional guidelines for the care and use of animals were followed.

Disclosure statement

No potential conflict of interest was reported by the authors.