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Polymerase chain reaction

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DNA on trial

The development of PCR and the use of the amplified DNA to produce unique individual profiles has brought many exciting developments, not least in medicine (see Infection detection and Impact of PCR on medicine) and the detection of crime (see PCR in forensic science).

However there are some people who are less than happy about the impact of PCR and other DNA technology on the society. They see opportunities for abuse, both in terms of our health care and in terms of crime detection.

The UK National DNA Database is the result of much research into the use of DNA technology in the fight against crime. At the moment this database holds only the DNA profiles of people who have been involved in the criminal justice system in some way. If a person is not convicted of a crime, their DNA is removed from the database. There is increasing pressure to have a DNA database of everyone, available to the police and for medical emergencies such as the need for organ or bone marrow transplants. Many people feel strongly about this idea, whether they are for it or against it.

Here are some snippets of information about DNA. Some are scientific fact. Some are speculation. Can you decide which are which?

DNA and evidence

Everyone talks as if DNA evidence is absolutely reliable, but it isn’t. The DNA profiles usually prepared only use part of our DNA. Most of the time this level of DNA fingerprinting is accurate enough to identify an individual – but things can go wrong.

Raymond Easton suffers from Parkinson’s disease and by the year 2000 he was so disabled that he could hardly manage to dress himself without help. In spite of this he was charged with a burglary which had taken place 200 miles away from his home! The error arose because three years earlier Raymond had been involved in a family dispute. He had been cautioned and a DNA sample was taken. By an amazing coincidence, Raymond’s DNA matched that found at the scene of the burglary. Fortunately DNA testing offered a way out of the situation it had created. Once a fuller DNA analysis was made, differences between Raymond’s DNA and that of the burglar became clear and the charges against him were dropped.

If different types of DNA analysis are done, the chances of there being a match range from 1 in 34 million to 1 in a billion.

DNA and transplants

Every 27 minutes, someone somewhere in the world receives an organ transplant. But every 2 hours 24 minutes someone dies waiting for a donor organ to turn up. When donor organs become available, it is vitally important that they are transplanted into someone who needs them as quickly as possible. What is more the tissue types of the donor and recipient must match as closely as possible. DNA profiles of donor and recipient can help to decide whether their tissues match.

If a central DNA database held the DNA profile of everyone (instead of being restricted to people convicted of criminal activities) then more people would be likely to receive successful organ transplants. What's more, organs could be used internationally far more easily.

DNA and life insurance

The various Human Genome projects, including the 1000 Genomes Project and the 100,000 Genomes Project, rely heavily on PCR to generate the DNA used in the analysis. Information from these projects is resulting in an ever-increasing understanding of the role of our genetics on our likelihood of developing many different illnesses, including heart disease, cancer, sight problems and diabetes.

There are concerns about who should have access to this sort of information. In most cases our genes don’t predict that we will definitely suffer from a disease, simply that we may be more likely to get it.

If insurance companies have access to people's DNA profiles they might refuse to give some people life insurance, or demand huge premiums.

DNA and terrorism

Since September 11th 2001 global terrorism has been seen as a real and massive threat to peace and security. The rise of Daesh (IS) and the terrible acts carried out in their name around the world has only heightened awareness of the threat of terrorism in every country.

If everyone's DNA profile was stored in an international DNA data bank, it could make it harder for terrorists to assume false identities and hide their origins. If terrorist attacks did occur, it would make tracing the terrorists much easier in order to bring them to justice.


Different people have very different views on the National DNA Database – here are two that you might hear:

I don’t want my DNA on some National DNA Database – how do I know the police won’t frame me for a crime I didn’t commit?

I don’t have a problem with the National DNA database. If you’ve got nothing to hide, you’ve got nothing to fear, have you? What’s more, it might help you get better medical treatment!

Currently, several countries have set up their own national DNA databases. Use the material here to produce two lists - one showing the arguments FOR a national DNA database open to the police in every country, the other giving arguments AGAINST such a database.

Then write a paragraph setting out whether or not you believe there should be a DNA database, explaining your reasons.