Why is Low Copy Number DNA testing controversial?
DNA profiling
There has been a recent case in Northern Ireland whereby an Omagh bombing suspect was cleared of all murder charges as the integrity of the forensic test which made up the bulk of the prosecution case was called into question.
The test in question is Low Copy Number DNA profiling or LCN DNA profiling. LCN testing allows genetic profiles of offenders to be created from very small tissue samples that have only been detectable with new techniques available since 1999. These can be as tiny as a millionth the size of a grain of salt which can amount to as little as a few cells of skin or sweat left in a fingerprint.
The Forensic Science Service (FSS) in the UK say they have used LCN DNA about 21,000 times and generated profiles from items such as matchsticks, weapon handles and grabbed clothing, some dating back to unsolved crimes. To do this, the minute samples, maybe comprising 1-2 strands of DNA, are magnified almost fifty times by PCR techniques and this is where critics say errors can creep in - if the DNA is damaged in any way, the replicated DNA will also include the damaged areas and therefore, may not truly reflect the original DNA. The worst case scenario is that it reflects an innocent person’s DNA.
Traditional or so-called “gold standard” DNA profiles are created using larger samples of genetic material and are not under scrutiny.
As a result Police Forces in the UK and Northern Ireland have suspended use of this test. In addition, other Police Forces around the world are reviewing cases where LCN DNA profiling resulted in the successful prosecution of suspects. Included in this are several high profile international cases including the murder of Swedish Foreign Minister Anna Lindh by Mijailo Mijailovic and in Australia, the murder of a backpacker Peter Falconio by Bradley Murdoch.
Elaine Warburton
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POSTED IN: DNA profiling, Forensics, Genealogy and DNA, General Genetics and Health, Genetic Future, Genetic Testing
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