News Analysis: Our DNA is unique, but that does not mean it belongs to usBy Charles Arthur, Technology Editor
22 May 2002
Steve Bing might not appreciate the irony, but the first use of DNA fingerprinting was also to solve a paternity case. Professor Sir Alec Jeffreys, who invented the process, was called upon to use it in April 1985, when a Ghanaian boy was stopped at Heathrow airport with an altered passport. He claimed citizenship through his mother, a British citizen. DNA samples were taken from him and from the British woman and her children living in this country. The samples matched: the boy was allowed to stay.
But, says Professor Jeffreys, of the genetics department at the University of Leicester, the whole sphere of the use of DNA is "a minefield" where ethical problems lie in wait all the time. And now it is all becoming much more urgent that we understand what protection is needed. "There's no technical obstacle at all in forecasting from someone's DNA what genetic diseases they will be prone to," the professor said. "And there have already been cases where DNA has been obtained by subterfuge."
Mr Bing claims that private detectives raided his dustbins for dental floss, to use as evidence in a paternity case in which he is claimed to be the father of a four-year-old child whose mother is divorcing an American billionaire.
However, DNA's best-known use is still in crime, where the police now collect thousands of samples every year and add the genetic identities of thousands of criminals to the National DNA database, which since 1995 has grown to hold 1.5 million samples.
But the debate launched yesterday by the Human Genetics Commission, the Government's think-tank, suggests there is a growing realisation that, unless important steps are taken, society will be overtaken by its technical ability to analyse DNA without having a legal framework in place to protect the privacy of that information.
Unless you are one of identical siblings twins, triplets and so on then your DNA is unique. At the same time, every cell in your body has the same DNA, or enough to make a full copy your "genome".
There are roughly three billion "base pairs" in every human genome. Reading out the sequence for every person would take years, as it did to sequence just 90 per cent of the full genome in the Human Genome Project, which announced its draft results in February 2001.
But DNA fingerprinting and paternity tests can be done much more quickly within an hour, if absolutely necessary in a police inquiry. If there is very little DNA (say, from flecks of saliva, or the root of a hair) then it is "amplified" in a chemical bath to produce millions more copies of the sample DNA.
Next, the copies are exposed to a "restriction enzyme"; this acts like chemical scissors, cutting the DNA only where particular combinations of the four base pairs occur. Because this differs for everyone, it produces a unique collection of snippets of DNA of different sizes. These can then be arranged on gel on a gradient where their movement will depend on their size. This produces the characteristic pattern of blobs that we know as the DNA fingerprint. It can be stored as a computer record, for rapid comparison, and the original sample (or its amplified version) can also be kept for long-term reconsideration.
While most people think of DNA fingerprinting being used to convict people, its first application by the police was to clear a suspect. In 1986 police hunting the killer of two women in Narborough, Leicestershire, sent samples from a self- confessed killer, and from the victims, to Professor Jeffreys. He showed that the DNA could not have come from the suspect, who was released. The killer, Colin Pitchfork, was found when everyone in the area was required to give a blood sample though he tried to avoid it and was caught.
The odds of two people giving matching DNA fingerprints are reckoned to be not far below one in a billion. But that has not stopped DNA evidence being challenged in the courts repeatedly. Professor Jeffreys says with a laugh: "Every aspect of DNA fingerprinting has been through the wringer. And it has survived."
In fact, he says, the rigour that must be used in collecting, storing and amplifying DNA samples where forensic science teams are aware that the slightest contamination with someone else's DNA from saliva or hair will create a false match has had the knock-on effect of improving the care that is applied to other scientific court work such as bullet-matching and fingerprinting.
DNA sequencing, and the idea that our fates are determined by our genome, was even picked up by Hollywood through the film Gattaca. This portrayed a future world where one's genome was chosen before birth for strength, intelligence and beauty depending on the finance one's parents had available. Instant DNA sequencing then created a world of haves and have-nots, where the genetic sequence in one's blood or saliva was the passkey or barrier.
That world is not so far off, some fear. Dr David King, of Human Genetics Alert, an independent watchdog, said yesterday that the regulations being proposed by the Human Genetics Advisory Commission which is putting its ideas forward to Parliament did not go far enough. "Instead of protecting the public, the HGAC seems scared of offending the medical research establishment," Dr King said. "After all the medical scandals, surely we deserve something better."
He thinks that the regulations need to start with a basic declaration of genetic rights, especially to privacy.
"There's a need for some law establishing the principle that genetic data is private, and that violating that privacy is an offence," Dr King said. "Presently, it's too easy for a researcher or medical worker to have access to a patient's named medical data without consent."
Insurers have a growing interest in being able to find out what diseases people will have or what they might die from; there is a voluntary ban by the industry on demanding genetic information but insurers can request that data which has already been acquired in other tests be revealed. Similarly, objections have been raised to the patenting of people's genes by companies. This happened, for example, in the creation of a particular line of cancer cells that are used all over the world for studying anti-cancer drugs. They came from a nun who died of breast cancer in 1970, but her cancerous cells are immortal, and were sold to the world by the Karmanos Cancer Institute. Similar rows have erupted over the liver cells of a patient at a different institution, who later found they were being sold without him receiving a penny.
"The [Government] report does not oppose the practice of patenting genes taken from patients' samples, despite widespread public concern about this," Dr King said. "Clear rules are desperately needed, but the Human Genetics Advisory Commission only remarks vaguely that 'a morally sensitive regime can and should be worked out'."
What is clear is that our genetic data, like any data about us, has value. But the Government, industry and the public disagree about what its price and value should be. Nothing in the HGAC's recommendations shows any sign that it will be sorted out soon.
Chemical clues - the dna profile
- DNA stands for deoxyribonucleic acid. The chemical, though not its structure, was isolated in 1869 by Friedrich Miescher, a Swiss scientist.
- The double helix structure of DNA was discovered in 1953 by James Watson and Francis Crick, helped by Rosalind Franklin and Maurice Wilkins, at the University of Cambridge.
- Teased out to its full length, a single human DNA molecule measures 1.7 metres (5ft 5ins).
- The outside of the helix consists of a sugar base; inside it, the three billion "steps" that make up the genome are combinations of the four "base pairs" the chemicals adenine, cytosine, guanine and thymine, or A, C, G and T. These form the alphabet which is made up into sequences forming "words" which tell the cell how to make genes. Humans have about 30,000 genes.
- DNA fingerprinting does not require the sequencing of a person's genome. A ''fingerprint'' can be produced from the DNA of a single cell.
- The DNA sample is "chopped up" into many smaller pieces by an enzyme to produce a collection of snippets which are unique for every person. Putting these snippets on to a gel with an electric field makes them move according to their size, producing the familiar spotted band of the DNA fingerprint.
- There is more than a 40 per cent chance of DNA found at a crime scene matching a name on the national DNA database. Samples can be taken from anyone charged, reported or cautioned. Last year it was used to solve some 14,800 crimes, compared with 8,600 the year before.
- Police can begin to build profiles of criminals from DNA found at crime scenes. So far they can tell if someone has red hair or blue eyes; other aspects are being worked on.
- British laboratories have made prototype paternity and other self-testing kits. They may be widely available in five years.
© 2002 Independent Digital (UK) Ltd