Sunday, September 12, 2004

DNA Fingerprinting not Foolproof ?

BRITAIN: A leading scientist says the growing number of profiles in police databases means more information is necessary to prevent accidental matches "If the DNA profile is partial because the sample is degraded, then accidental matches often occur. However, it is important to remember that the national DNA database is an intelligence database." Sir Alec Jeffreys, a geneticist at Leicester UniversityThe genetic profiles held by police for criminal investigations are not sophisticated enough to prevent false identifications, according to the father of DNA fingerprinting.Sir Alec Jeffreys, a geneticist at Leicester University, England, said police DNA databases should hold more information to lessen the chances of a false positive.He was speaking at a briefing to mark the 20th anniversary of his pioneering of DNA fingerprinting.Genetic profiles stored by police normally record the details of 10 specific parts of the long chain of molecules that make up a person's DNA. The chances of two unrelated people having the same details for all these 10 markers -- and hence the chance of a false identification -- is said to be about one in a billion. This method has traditionally been regarded as highly efficient at identifying suspects from DNA traces left at crime scenes.However, Jeffreys said the increasing number of records being held on the UK police database -- currently about 2.5 million -- meant that having only 10 markers per person was no longer foolproof.He suggested 15 or 16 markers to reduce the chances of two people having the same profile to one in more than a trillion. American law-enforcement authorities are already considering changing the profiles in their DNA databases along these lines.In Britain, DNA evidence has been used in countless criminal investigations and the police regard it as an invaluable tool. Peter Gill, of the UK's Forensic Science Service, which administers the British DNA database for the police, said his agency was "confident that the 10 markers currently used are sufficient.""The chance of an accidental match is fairly small, yet we never discount the possibility, and all our reporting officers are aware of this," he said."If the DNA profile is partial because the sample is degraded, then accidental matches often occur. However, it is important to remember that the national DNA database is an intelligence database," Gill said."This means that before a decision to prosecute can be given, all of the evidence in the case must be carefully considered. DNA is never reported in isolation. The jury makes its decision based on all of the evidence presented," he said.Jeffreys also gave a warning against keeping DNA records of people who had been wrongly suspected of crimes -- something UK police have been legally allowed to do since 2001.In certain parts of the country, this could lead to an over-representation of certain ethnic groups and could lead to resentment, he said. The solution was either to delete records of those who had been cleared of any offence or simply to extend DNA profiling to everyone in Britain.He also expressed reservations about the idea of extracting anything more than simple identification data from DNA. "Police store not only the DNA profile but also the physical DNA," Jeffreys said. "If they have that, there is the long-term risk that people could access health information in the future. Police have absolutely no right to that information."He sought to calm civil liberty fears that police might reach the stage of producing Photofits based solely on DNA information, saying science would be a limiting factor.There are few robust tests for identifying physical characteristics from someone's DNA -- such as hair and eye color and broad ethnic origin -- although research in the area is continuing.


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