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Advancing Forensic DNA with Next-Gen Sequencing

by
Carey Davis
| Oct 22, 2012

multiplexing next-gen sequencingEating way too much delicious food, charming the exhibitors out of their best swag, making obligatory body fluid jokes, and of course listening to presentations from around the world, the 2012 International Symposium on Human Identification (ISHI) started just like any other forensic conference. The difference this time was that I had to actually present in front of this group, and on a topic I was not sure would be well-received: Next-Generation Sequencing (NGS).

Forensic DNA is a Class of its Own

Even though my heart would have won a speed race with a hummingbird, my curiosity of how the community felt about NGS overcame my fear of public speaking. I was pleasantly surprised to find that none of my nightmares came true, and that the forensic science community is quite intrigued by NGS and what it can do to change how we process human identification samples. Most of the people I had the chance to speak with are ready for the next big change to catapult forensic DNA further into a forensic class of its own. In fact, several other laboratories also have started to work with NGS companies to examine forensic markers, and presented their progress at this conference. With the launch of the newest capillary electrophoresis forensic DNA kits, we have hit the limit of this technology’s capabilities. While these kits provide more information than we thought possible 10 years ago, we know that NGS could radically change how much information we can glean from one sample. Instead of spending hours changing kits to capture different locations, all markers can be analyzed at once. As someone who has had to switch kits often, this sounds almost too good to be true. If I had not tried it myself, I am not sure I would have believed it.

Braving the Uncertainty of Multiplexing

I quickly found that those who did have concerns with this new technology had the same trepidations I had when I first tried NGS. As a forensic DNA analyst, mixing samples of any kind is a cry-worthy and in some cases fireable offense. The idea that more than one person can be analyzed at the same time was incredibly foreign and downright scary to me. After running several sample preparation methods from different companies and seeing how the index system works, I am much more comfortable with “mixing” the samples. As the samples are tagged with their own barcode or index, they share the same space but are easily distinguished from each other. With this strategy, even if cross contamination occurred after the barcoding process, we could still use all that data. I also had heard stories of sample preparation taking weeks of constant manual labor. This was quickly quashed when I did the sample preparation. While the sample preparation involves a few manipulations, it is not nearly as complicated as I thought it would be. Also, the technology is rapidly evolving, allowing smaller input amounts and faster preparation times with each iteration.

Anticipating Improvements

I understood the concerns I heard at this meeting, but some sounded eerily similar to those same apprehensions as when the community switched from slab gels to capillary electrophoresis. As technology improves, so should our techniques. While a commercial forensic DNA kit for NGS is not yet available, I think we will see one much sooner than most of us originally thought possible. I left this meeting with excitement about the future of the forensic DNA community, and it seemed many of my colleagues did as well.        

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