Fast track DNA fingerprints

As forensic experts struggle to identify the victims of the terrorist attacks in New York and Bali, researchers in Australia announced at a science forum last week that they have refined and tested a DNA fingerprint procedure that will leave conventional techniques in the dust.According to team leader Ian Findlay of the Australian Genome Research Facility (AGRF), located at the University of Queensland in Brisbane, the new system is nearly twice as fast as conventional DNA fingerprint technology. Moreover, profiles are derived from DNA contained in a single cell — existing procedures require at least 500 cells.Findlay claims his team can crank out 1,000 samples a day — most laboratories manage a few dozen — and each to a specificity of ten billion to one. "That's better than the population of the planet and probably everyone who's ever been on the planet," said Findlay, a medical geneticist.If the technology meets expectations, "there is no doubt it will be a very powerful tool for forensic science," said forensic biologist Alastair Ross, director of the National Institute of Forensic Science in Melbourne.At the forum, held October 29 at the University of Technology, Sydney, Findlay predicted the system will extend the range of forensic sources beyond blood, semen and other body products. Paper, clothing, glass, and plastics could provide evidence.Once DNA fingerprints are gleaned from these sources, they can be compared to databases containing millions of profiles. That's possible because the system is based on short tandem repeats (STR). In contrast, databases do not exist for profiles derived with the rival single nucleotide polymorphism (SNP) technology.According to Findlay, ideal applications include document fraud and money laundering. "It may now be possible to not only determine the authenticity of documents and track their movements, but also to identify every person who has touched them. Even if the perpetrators wear gloves, there still could be skin cells on the outside of the gloves," he said.Although the reported results are impressive, Ross agrees with Robert Goetz — a crime scene forensic biologist with the New South Wales Public Health Division of Analytical Laboratories — that the technology must be used with caution. Goetz notes that investigators must ensure they have the "right" sample. "If I looked at your T-shirt, how many cells don't belong to you?" he asked. Both Ross and Goetz concede, however, that a good single-cell procedure may reduce the problem of contaminated samples. As Findlay explains, extraneous DNA appears as "extra peaks" for one or more of the 16 markers used, and tainted samples are "tossed out."In addition to forensic applications, Findlay's team is testing the technology with in vitro fertilization (IVF) procedures, the application for which Findlay originally designed single-cell analysis. For instance, they are screening pre-implantation embryos for genetic defects and confirming paternity. "You have to make sure you return the right embryo," noted Findlay, pointing to recent cases in which UK couples may have received the wrong embryo during IVF.The group has also conducted pre-natal genetic screening, using fetal cells obtained from a pap smear taken from the mother.Details of the technique are slim because Findlay and collaborators at the AGRF and Queensland Health's John Tonge Centre in Brisbane have applied for patents on the procedure and its IVF applications.Regardless, the technology builds on work that Findlay and colleagues published in 1997. There they reported a system for determining STR fingerprints, from a single cell, with a specificity of roughly 50 million to one.Although Findlay acknowledges that the system needs independent validation, he's bullish about its potential: "It's such a breakthrough we're waiting for the rest of the world to catch up."

Fast track DNA fingerprints

Australian researchers claim to have refined a technique that will revolutionize forensics.

Interested in reading more?

Become a Member of