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Probabilistic Genotyping of Evidentiary DNA Typing Results – An Online Workshop Series
Module 4: Validation of Probabilistic Genotyping Systems for Casework Usage

Original webinar took place on Wednesday, May 29th, 2019 from 12:00:00 PM ET – 4:00:00 PM ET
Duration: 4 hour(s)

The Scientific Working Group on DNA Analysis Methods (SWGDAM) and other bodies have published guidelines that specify empirical studies to be performed to assess reliability, identify limitations and develop suitable usage conditions for probabilistic genotyping systems. In this installment of the web series Probabilistic Genotyping of Evidentiary DNA Typing Results, we discuss the intent of each validation requirement and provide examples of their execution, as well as resulting data and how they can be used to develop standard operating procedures within the forensic DNA testing laboratory.


Tamyra Moretti – Federal Bureau of Investigation, Quantico, Virginia
Sarah Noël – Laboratoire de Sciences Judiciaires et de Médecine Légale, Montreal, Canada
Duncan Taylor – Forensic Science South Australia, Adelaide, Australia

Detailed Learning Objectives:

· Appraise developmental validation studies and construct an internal validation plan based on the SWGDAM Guidelines for the Validation of Probabilistic Genotyping Systems
· Evaluate experimental data relating to hypothesis testing, precision, repeatability, sensitivity, specificity, various numbers of contributors, contributor proportions in DNA mixtures and total DNA template amounts
· Examine validation results generated by other laboratories and learn how to relate the findings into the development of reliable standard operating procedures, with an understanding of the limitations of a probabilistic genotyping system.

Recommended Reading:

Bright, J.-A. et al. Internal validation of STRmix™–A multi laboratory response to PCAST. Forensic Science International: Genetics 2018; 34, 11-24.

Moretti, T.R. et al. Internal validation of STRmix for the interpretation of single source and mixed DNA profiles. Forensic Science International: Genetics 2017; 29, 126-144.

Scientific Working Group on DNA Analysis Methods. SWGDAM Guidelines for the Validation of Probabilistic Genotyping Systems. Approved June 15, 2015. Available at https://docs.wixstatic.com/ugd/4344b0_22776006b67c4a32a5ffc04fe3b56515.pdf.

Noël, S., Noël, J., Granger, D., Lefebvre, J.-F., & Séguin, D. (2019). STRmixTM put to the test: 300 000 non-contributor profiles compared to four-contributor DNA mixtures and the impact of replicates. Forensic Science International. Genetics, 41, 24–31. https://doi.org/10.1016/j.fsigen.2019.03.017


Funding for this Forensic Technology Center of Excellence event has been provided by the National Institute of Justice.


Please read this short announcement and follow the registration instructions below.

RTI International and the National Institute of Justice’s Forensic Technology Center of Excellence are continually striving to bring you the optimum learning experience when delivering our online events and webinars. To better disseminate our content to the growing forensic community, we are pleased to announce that we are starting to host our events on a new virtual platform. This platform will provide a better user interface, putting more content, discussion, and knowledge at your fingertips.

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Step 1: Go to https://learning.forensicac.org/login/signup.php to create a new account.

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