Examination of Witnesses (Questions 154-159)
Professor Peter Hutton, Professor Graeme Laurie and
Dr Helen Wallace
30 JANUARY 2008
Q154 Chairman: Could I welcome you,
Professor Hutton, Professor Laurie and Dr Wallace. It is extremely
good of you to come and give evidence. We are not being televised
but we are being recorded, so I would ask you, if I may, to state
your names and organisations for the record, and thereafter to
make a short opening statement if you so wish.
Professor Hutton: My name is Professor
Peter Hutton; I am here as the Chairman of the National DNA Ethics
Group, which was set up as a non-departmental public body on 25
July last year. My full time employment is as a Professor of Anaesthesia
and Honorary Consultant at the University Hospital, Birmingham,
and Birmingham Medical School.
Professor Laurie: Good morning; I am
Professor Graeme Laurie from the University of Edinburgh Law School.
I am also here as a representative of the Nuffield Council on
Bioethics. I was recently a member of the Working Group on ethical
issues related to bioinformation, and the terms of reference of
that Council are to identify and define ethical questions raised
in respect of biomedicine and bioethics and to report publicly
on those issues.
Dr Wallace: My name is Dr Helen Wallace.
I am the Director of GeneWatch UK, which is a small, not for profit
organisation set up about ten years ago. Our aim is to ensure
that genetics is used in the public interest and to stimulate
public debate about the applications of genetic technology.
Q155 Chairman: Would anybody like
to make a brief opening statement or shall we go straight to questioning?
Professor Hutton: I am happy to go to
the questions.
Q156 Chairman: Could I ask, to begin
with, if you could give us a brief explanation of the nature of
DNA samples and profiles and how they are collected? And to what
extent is the technology advancing?
Professor Hutton: The DNA which is present
in almost every cell of our body is identical on every occasion,
although its activity differs from cell to cell. Of the DNA which
is present in the cell only five per cent of that DNA is actually
used to make body cells and components; the remaining 95 per cent
of the DNA is what is termed scientifically as redundant DNA,
that is, it has no known purpose in producing the cells of the
body. It has other purposes about which people speculate, such
as providing structural integrity to the molecule. When a forensic
DNA test is done it is the redundant part of the DNA which is
tested, not the section which is responsible for the production
of cells. When we are conceived, we inherit 50 per cent of our
DNA from our mother and 50 per cent from our father. The gene
which, for instance, produces a normal compound such as insulin
is probably the same in each parent. However, the redundant components
of DNA differ greatly from person to person and that it is why
it is that section which is used to differentiate identity. The
tests which are done are done by applying substances called primers
which stick to particular components of the DNA. Depending upon
where they stick and the amount that they stick to determines
your DNA profile, and that emerges either on a paper printout
or on an electronic screen as a series of numbers and peaks, and
for any one individual 50 per cent of those numbers and peaks
will be determined by their mother and 50 per cent by their father.
That is also true of a sibling but it is a different 50 per cent
from each parent. In that way siblings are similar but inherently
different to each other. The tests which are used in Britain are
based on a system called SGM Plus, which stands for Second Generation
Multiplex—that is the name of the machine—and Plus
because it is a more advanced test. This tests the redundant DNA
at ten positions and also identifies the sex chromosomes, and,
in comparing DNA if you test the ten positions together with the
sex chromosome the chance of a match at random is one in a billion.
I think perhaps, my Lord, if I stop there people could ask questions.
Q157 Chairman: Thank you very much
indeed. Could I ask what estimate you would make about the reliability
of DNA samples and profiles in the context of law enforcement?
Dr Wallace: Perhaps I could answer that?
I think it is clearly highly reliable; if you have a complete
DNA profile from the individual and a complete DNA profile from
the crime scene the match probability is roughly one in a billion.
Q158 Chairman: Could you say that
again?
Dr Wallace: The probability of a match
with an unrelated individual, if you have two full profiles, is
around about one in a billion. However, there are quite a number
of steps along the process where problems can arise. First, you
will notice that I said an unrelated individual—there is
of course a potential that relatives become the subject of an
investigation and may be wrongly implicated. Secondly, there is
a big issue about crime scene DNA but the crime scene itself is
obviously a messy place to collect DNA samples and many of those
samples do not give a complete DNA profile. So, for example, in
2005/2006 something like 50,000 of the match reports sent to the
police involved a list of potential suspects and that was largely
due to the fact that the crime scene DNA profiles were not complete.
So it is a misunderstanding to think that a single individual
is often implicated in the crime. The second point to emphasise
also is that at a crime scene many people may have been present
who are not necessarily the perpetrators, so you may also have
a match with someone who has been at the crime scene earlier in
the day, for example.
Professor Laurie: May I just add that
one of the significant technological developments that struck
the Working Group was the ability to obtain DNA from smaller and
smaller samples, known colloquially as low copy number, and this
has been heavily criticised in the recent Omagh bombing trial
and is currently being investigated by Sir Brian Caddy at the
request of the interim Forensic Regulator. One of the concerns
is the lack of scientific and international agreement about the
reliability of this in terms of what it can actually say for matches
in criminal trials and we understand that it has been reported
that only three countries routinely rely on this sort of evidence—the
United Kingdom, the Netherlands and New Zealand. Such a review
was welcomed by the group because one of the main concerns of
the Working Group was public trust and confidence in the quality
of the forensic service provision.
Q159 Baroness Quin: In the account
of the ethical issues of the organisation in which you are involved
it does say in paragraph three that in particular there are dangers
of deliberate or accidental contamination, misinterpretation of
mixed samples and mistaken interpretation of the partial profile.
Are there examples that you know of where this has happened and
where injustice has resulted?
Professor Laurie: It is important to
understand the context in which the report was actually drafted.
It was not really the business of the Council to try and look
for case studies; it was more to reassess the fundamental ethical
principles upon which our entire system is actually based. A lot
has to go wrong before there are actual specific incidences of
miscarriages of justice but what comes out of our report is that
the ethical principles we feel should inform the entire process
are those of liberty, privacy and autonomy and there can be many
intrusions on an individual's privacy before they actually get
to court and before that may lead to problems of miscarriage,
and it was really about getting the balance right between what
is in the interests of society and the prosecution and detection
of crime and citizens' interests of privacy and liberty.
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