LCN DNA: proof beyond reasonable doubt? — a response
2008; Nature Portfolio; Volume: 9; Issue: 9 Linguagem: Inglês
10.1038/nrg2362-c1
ISSN1471-0064
Autores Tópico(s)Genomics and Phylogenetic Studies
ResumoIn the article by McCartney (LCN DNA: proof beyond reasonable doubt?Nature Rev. Genet.9, 325 ( 2008)) 1 , it is argued that the Omagh trial had exposed serious flaws in the DNA evidence.However, much of the evidence was not reported by the media, neither did it feature in the judgement itself.The scientist's role is to dispassionately advise the court on the meaning of evidence.Consequently, failure to convict does not translate into failure of science.This correspondence is an attempt to place the verdict into context.Forensic samples are often less than pristine -they might be degraded, or the DNA might be present as low-template DNA (LT-DNA).This results in partial profiles, with 'missing' alleles.If a sample is a mixture of two or more contributors then additional alleles are present.The sample might concurrently be a mixture and LT-DNA.It follows that a well represented (matching) profile can be interpreted without difficulty, regardless of the method used, whereas mixtures and LT-DNA are interpreted using different principles 2,3 .To improve sensitivity of the test, different 'enhancement' methods might be used by laboratories to increase the signal.Increased PCR cycle number is one such method, but LT-DNA can be analysed without using any specific enhancement method 4 ; in practice, all forensic laboratories encounter and report such profiles.A misleading impression has been given that all of the DNA profiles in the Omagh case were poor quality.However, some
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