Low copy number

Low Copy Number (LCN) is a DNA profiling technique developed by the Forensic Science Service (FSS) and in use in some countries since 1999.

In the United Kingdom the technique was briefly suspended from use between 21 December 2007 and 14 January 2008 while the Crown Prosecution Service conducted a review into its use - this suspension has now been lifted. [ [http://www.cps.gov.uk/news/pressreleases/101_08.html CPS Press Release : Review of the use of Low Copy Number DNA analysis in current cases: CPS statement ] ]

LCN is an extension of Second Generation Multiplex Plus (SGM Plus) profiling technique. It is a more sensitive technique because it involves a greater amount of copying from a smaller amount of starting material, meaning that a profile can be attained from only a few cells, which may be as small as a millionth the size of a grain of salt, and amount to a just few cells of skin or sweat left from a fingerprint. [ [http://news.bbc.co.uk/1/hi/uk/7156051.stm DNA test halted after Omagh case] , BBC ]


LCN evidence has allowed convictions to be made in several cold cases. For example, Mark Henson was convicted of rape in 2005, 10 years after the crime was committed, from re-analysis of a microscope slide. In 1981, evidence was deliberately kept after the rape and murder of 14 year old Marion Crofts. In 1999, a DNA profile was attained from this using LCN. This was continually checked against the UK National DNA Database for the next two years, until a match was eventually found for Tony Jasinskyj after he was arrested for another crime. He was eventually given a life sentence in 2002. [ [http://www.forensic.gov.uk/forensic_t/inside/news/list_press_release.php?case=15&y=2002 Marion Crofts] , FSS]

So far the technique is only used in three countries: the UK, the Netherlands and New Zealand.


The technique came under attack from the Judge during the trail of Sean Hoey - who was eventually cleared of involvement in the Omagh Bombing. One of the criticisms the judge leveled at LCN was that although the FSS had internally validated and published scientific papers on the technique, there was an alleged lack of external validation by the wider scientific community. [ [http://business.timesonline.co.uk/tol/business/law/article3083217.ece Judgment in full: the Queen v Sean Hoey - Times Online ] ] Following the Judge's ruling, the use of the technique was suspended in the UK, pending a review by the Crown Prosecution Service. This review was completed and the suspension lifted on the 14 January 2008. [ [http://www.cps.gov.uk/news/pressreleases/101_08.html CPS Press Release : Review of the use of Low Copy Number DNA analysis in current cases: CPS statement ] ] In its press release the CPS stated:-

"From this, the CPS has not seen anything to suggest that any current problems exist with LCN. Accordingly we conclude that LCN DNA analysis provided by the FSS should remain available as potentially admissible evidence. Of course, the strength and weight such evidence is given in any individual case remains a matter to be considered, presented, and tested in the light of all the other evidence."



* [http://www.forensic.gov.uk/forensic_t/inside/news/documents/DNA_Low_Copy_Number_000.doc Science Behind the Technique] , FSS
* [http://www.guardian.co.uk/uk/2008/jan/16/ukcrime.forensicscience Case closed] , "The Guardian", January 16 2008
* [http://www.bioforensics.com/statements/Krane_Hoey_statement.pdf Statement of Dan E. Krane in the case of R. v. Sean Hoey] , October 24 2006

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