(Philadelphia, PA - May 2002) In the aftermath of the September 11 terrorist attacks, the National Justice Department sent out a plea for new technologies that could assist in the investigation at Ground Zero. How two Denver scientists stepped up to the challenge with a new approach to speed DNA identification at this and other disaster sites is the focus of an article by contributing writer, Kelli A. Miller, in the current edition of The Scientist, "Identifying Those Remembered" (June 10, 2002).
Phil Danielson, an assistant professor of molecular biology at the University of Denver, and his laboratory assistant Robby Shelton, a pre-med student, identified a technology that cuts down the DNA analysis time from days to minutes, reduces costs from $2,500 to $10 per sample and decreases the forensic sample needed by 99.5%.
In a pilot study, Danielson and Shelton demonstrated that WAVE profiling, one of the most...
The most common type of DNA profiling notes differences in the size of specific nuclear DNA regions known as Short Tandem Repeats (STRs). But at ground zero in New York, and at many mass disaster scenes, very little nuclear DNA evidence remains. That's when mitochondrial DNA (mtDNA) comes into play. Every cell in the human body contains thousands of copies of maternally inherited mtDNA. Since all maternal relatives have the same "mitotype," forensic scientists can identify victims from tiny samples by matching DNA obtained from relatives, even when no body is found. "We use mitochondrial DNA when there's almost nothing left. It's our last hope," admits Danielson.
Traditionally mitotyping is a laborious process that requires extensive post-electrophoretic sequence analysis. It works, but it takes 10 to 100 times longer than STR analysis in terms of time and materials.
Danielson's technology represents a radical departure from existing mitotyping. Armed with forensic samples provided by Greggory LaBerge, a forensic scientist at the Denver Police Department, and Transgenomic's WAVE Nucleic Acid Fragment Analysis System, LaBerge, Danielson, and Shelton designed a method that completely eliminates the need for direct DNA sequencing and the time-consuming interpretation of results. Their approach takes an instant snapshot of the entire mtDNA molecule in just one step. "We're taking molecular biology and combining it with forensics to do something that's going to have a major impact," explains Danielson.
"Right now, sequencing takes 85 minutes to run one sample and analysis and interpretation can take hours to days," says Shelton. "The WAVE instrument completes the analysis in as little as four minutes."
Police departments have been slow to adopt mitotyping; it's just too expensive. Now, Danielson's mtDNA method could dramatically cut costs. "Robby [Shelton] improved the sensitivity of some FBI methods by orders of magnitude, while cutting costs from $2,500 per sample to less than $10 per sample," explains Danielson. And they did so using samples much smaller than those required nowadays. Forensic labs usually request a hair shaft at least two centimeters (cm) in length; Danielson and Shelton obtained useable DNA mitotypes from as little as 0.01 cm of hair.
Danielson says the federal government's response to his research has been encouraging. His team is now waiting for the thumbs up to fully develop and forensically validate the use of DHPLC and WAVE profiling for criminal investigations and the identification of human remains from mass disasters like the 9-11 terrorist attacks. "Identifying the victims from the World Trade Center will likely take years," he says. "Hopefully in the middle of this, WAVE profiling will be approved to help dramatically speed things up."
Kelli A. Miller (science@mindspring.com) is an Atlanta, Ga.-based science and medical writer.
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