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A sequence-based 74plex microhaplotype assay for analysis of forensic DNA mixtures
Fabio Oldoni1, Drew Bader1, Chiara Fantinato1
1The George Washington University, Department of Forensic Science, 2100 Foxhall Road, NW, Washington, DC, 20007, United States.
Forensic Science International. Genetics
|September 12, 2020
Summary
A new 74 microhaplotype assay effectively analyzes forensic DNA mixtures, detecting minor profiles down to a 20:1 ratio. This sequence-based method enhances mixture deconvolution compared to traditional STR analysis.
Area of Science:
- Forensic genetics
- Human genomics
Background:
- Microhaplotypes are increasingly utilized as forensic biomarkers.
- Current forensic DNA analysis faces challenges with complex mixtures.
Purpose of the Study:
- To develop and evaluate a sequence-based multiplex assay for 74 microhaplotypes (230 SNPs).
- To assess the assay's efficacy in deconvoluting forensic DNA mixtures.
Main Methods:
- Development of a 74-plex microhaplotype assay on the Ion Torrent S5™ system.
- Evaluation of typing performance using in-silico DNA mixtures (2-5 contributors).
- Comparison with fragment and sequence-based Short Tandem Repeat (STR) analysis.
Main Results:
- The assay is sensitive down to 0.05 ng input DNA.
- Microhaplotypes detected minor profiles at ratios as low as 20:1 (10 ng input) with minimal dropout at 1 ng.
- The microhaplotype panel outperformed CE-STRs in detecting minor alleles in imbalanced mixtures.
Conclusions:
- The developed microhaplotype panel is a powerful tool for forensic mixture analysis.
- This assay complements and improves upon existing STR-based methods for DNA mixture deconvolution.
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