[IP] DNA may tell police the surname of the criminal

[Dave Farber]

-------- Original Message --------
Subject: DNA may tell police the surname of the criminal
Date: Wed, 22 Feb 2006 13:09:16 +0000
From: Brian Randell <Brian.Randell at newcastle.ac.uk>
To: dave at farber.net

Hi Dave:

>From today's (UK) Guardian:


>How DNA may tell police the surname of the criminal
>
>Alok Jha
>Wednesday February 22, 2006
>The Guardian
>
>Police will soon be able to predict the surnames of criminals whose
>DNA is found at crime scenes, according to research published
>yesterday. The technique would only work in finding men, however, as
>it is based on identifying similarities in the Y chromosome, which
>is passed from father to son.
>
>The technique relies on research carried out by University of
>Leicester scientists into how Y chromosomes have spread through the
>British population. They analysed these chromosomes in 150 pairs of
>men with the same surname and found that, in a quarter of cases, the
>pair had matching Y chromosomes.
>
>When the most common names were excluded from the list - Smith,
>Jones, Williams and Taylor, for example - the chance that two men
>with the same surname shared a Y chromosome jumped to 50%. The
>research appears in the latest edition of Current Biology.
>
>Mark Jobling, a geneticist at the University of Leicester who led
>the work, said the police would need a relatively small collection
>of male DNA - around 40,000 people - to allow useful matches to be
>made. "That sounds big but the national DNA database is nearly 100
>times bigger," he said. By matching the Y chromosome details of
>unidentified DNA at a crime scene with the database, police would
>get a list of potential surname matches.
>
>"That would allow you to prioritise suspects in your investigation,"
>said Dr Jobling. "If you have a lot of suspects - say a whole town
>or something - you can say we have 50 names, are these names
>represented here, if so let's go and interview these people."
>
>Y chromosomes are passed from father to son mostly unaltered. Once
>in a while, they will acquire random mutations as they pass through
>the generations. Some parts of the chromosome are known to mutate
>less rapidly than others and, by mapping these differences,
>scientists can create a tree showing the relationships between
>different Y chromosomes.
>
>"If men fall in different branches of the tree, there's no way they
>can be related to a recent male ancestor," said Dr Jobling. "If they
>lie within the same branch, there is a chance they are, but it
>doesn't prove it.
>
>"When we do that simple test, we find that a highly statistically
>significant excess of pairs share a branch of the tree, much more
>than we expect by chance."
>
>It is a surprising result, since there are plenty of reasons why
>people might have the same surname but be unrelated: many names were
>founded by more than one man, for example. There is also the issue
>of illegitimacy. The researchers predicted that more than 1% of
>children were illegitimate in each generation. Over many
>generations, this could have built up a significant error.
>
>"Those two elements would act as a strong force to break any links,"
>said Dr Jobling. "It was a surprise that by choosing just pairs we
>got a clear signal of sharing ancestors."


http://www.guardian.co.uk/crime/article/0,,1715022,00.html




--
School of Computing Science, University of Newcastle, Newcastle upon Tyne,
NE1 7RU, UK
EMAIL = Brian.Randell at ncl.ac.uk   PHONE = +44 191 222 7923
FAX = +44 191 222 8232  URL = http://www.cs.ncl.ac.uk/~brian.randell/

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