Background

Accurate DNA profiling from compromised samples, such as those that are highly degraded or contain potent inhibitors, remains a significant challenge in forensic science and human identification. Conventional STR kits often fail to yield complete profiles when the DNA template is fragmented. To address this, we developed a novel, high-performance Mini-STR genotyping system.

Methods and Design

The kit targets 18 STR loci, encompassing all European Standard Set (ESS) requirements, and is fully compatible with existing laboratory genetic analyzers. The system is strategically designed with two multiplex panels (Panel A and Panel B) for simultaneous amplification. To maximize success with degraded DNA, the amplicon sizes are significantly reduced:

1. Panel A: All 9 loci feature maximum fragment sizes of less than 225 bp.
2. Panel B: 7 of the 9 loci are under 225 bp, with the remaining highly informative loci (SE33 and FGA) kept under 280 bp.The kit is provided in a lyophilized (freeze-dried) format, pre-dispensed in individually capped 8-strip tubes.

Results

Performance evaluations demonstrate exceptional sensitivity, achieving a 100% locus call rate with as little as 0.0625 ng of input DNA. Furthermore, the system exhibits superior tolerance to common environmental inhibitors, including humic acid and hematin. The lyophilized format allows for "full-volume" sample loading (up to the maximum capacity of the reaction), which significantly enhances the detection capability for ultra-trace samples.Conclusion: This combination of mini-STR design and advanced stabilization technology offers a robust, user-friendly solution for challenging forensic casework. By reducing the amplicon size and minimizing human-induced contamination via the pre-filled 8-strip design, this system provides a reliable tool for human identification from highly compromised biological evidence.

Keywords

Forensic Science; Mini-STR; DNA Degradation; Lyophilization; ESS Loci; Trace DNA

Authors

• Dongke Fu (NuHigh Biotechnologies Co.Ltd, China)
• Wanli Bi (NuHigh Biotechnologies Co.Ltd, China)