Low copy number
Encyclopedia
Low Copy Number is a DNA profiling technique developed by the Forensic Science Service
(FSS) and in use in some countries since 1999.
In the United Kingdom use of the technique was suspended 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.
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 obtained 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.
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.
So far the technique is only used in several countries:the UK, the Netherlands
and New Zealand
.
. 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. 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 January 14, 2008 with the CPS stating that it had not seen anything to suggest that any current problems exist with LCN".
The increased sensitivity of LCN also increases the risks posed by contamination of samples in the laboratory. Since LCN aims to amplify levels of DNA as low as 100 picograms, even breathing on a sample may contaminate it substantially enough to render the final profile unusable. Contamination is particularly problematic before the sample has undergone amplification because both the suspect's and the contaminator's DNA will be amplified, resulting in a mixed profile. Moreover, the small amounts of DNA that LCN aims to amplify also increase the probability of PCR artefacts appearing on profiles such as stochastic effects.
Forensic Science Service
The Forensic Science Service is a government-owned company in the United Kingdom which provides forensic science services to the police forces and government agencies of England and Wales, as well as other countries.-History:...
(FSS) and in use in some countries since 1999.
In the United Kingdom use of the technique was suspended between 21 December 2007 and 14 January 2008 while the Crown Prosecution Service
Crown Prosecution Service
The Crown Prosecution Service, or CPS, is a non-ministerial department of the Government of the United Kingdom responsible for public prosecutions of people charged with criminal offences in England and Wales. Its role is similar to that of the longer-established Crown Office in Scotland, and the...
conducted a review into its use - this suspension has now been lifted.
LCN is an extension of Second Generation Multiplex Plus
Second Generation Multiplex Plus
Second Generation Multiplex Plus , is a DNA profiling system developed by Applied Biosystems. It is an updated version of Second Generation Multiplex...
(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 obtained 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.
Advantages
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 obtained from this using LCN. This was continually checked against the UK National DNA DatabaseUK National DNA Database
The United Kingdom National DNA Database is a national DNA Database that was set up in 1995. As of the end of 2005, it carried the profiles of around 3.1 million people...
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.
So far the technique is only used in several countries:the UK, the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
.
Criticism
It has been used in more than 21,000 serious crime cases in the UK and internationally, particularly in "cold" cases. A FSS spokesman said: "LCN DNA analysis is only carried out by the most-experienced DNA scientists, who have undergone special additional training and testing in this area of casework." However, the technique came under attack from the Judge during the trial of Sean Hoey - who was eventually cleared of involvement in the Omagh BombingOmagh bombing
The Omagh bombing was a car bomb attack carried out by the Real Irish Republican Army , a splinter group of former Provisional Irish Republican Army members opposed to the Good Friday Agreement, on Saturday 15 August 1998, in Omagh, County Tyrone, Northern Ireland. Twenty-nine people died as a...
. 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. Following the Judge's ruling, the use of the technique was suspended in the UK, pending a review by the Crown Prosecution Service
Crown Prosecution Service
The Crown Prosecution Service, or CPS, is a non-ministerial department of the Government of the United Kingdom responsible for public prosecutions of people charged with criminal offences in England and Wales. Its role is similar to that of the longer-established Crown Office in Scotland, and the...
. This review was completed and the suspension lifted on the January 14, 2008 with the CPS stating that it had not seen anything to suggest that any current problems exist with LCN".
The increased sensitivity of LCN also increases the risks posed by contamination of samples in the laboratory. Since LCN aims to amplify levels of DNA as low as 100 picograms, even breathing on a sample may contaminate it substantially enough to render the final profile unusable. Contamination is particularly problematic before the sample has undergone amplification because both the suspect's and the contaminator's DNA will be amplified, resulting in a mixed profile. Moreover, the small amounts of DNA that LCN aims to amplify also increase the probability of PCR artefacts appearing on profiles such as stochastic effects.