DNA fingerprinting

In 1984, Professor Sir Alec Jeffreys discovered that certain parts of your DNA (not the genes but other bits called VNTRs) are very variable within the population. However, these VNTRs are similar among related individuals. He used this to make DNA profiles (genetic fingerprints) of people. DNA fingerprinting is a way of comparing DNA samples to see if they come from the same person, from two different people or from related people. It works by screening for certain DNA sequences which are found in some individuals but not others.

Uses of DNA fingerprinting In forensic science – DNA (from hair, skin flakes, blood, semen, etc.) taken from a crime scene is compared with a DNA sample taken from a suspect. It has led to many criminal convictions for rape and murder and has also shown if a person is innocent of a crime, sometimes after being wrongly convicted. In 1986, Colin Pitchfork was the first criminal convicted in the UK using DNA fingerprinting.

Martin Shields/Science Photo Library DNA fingerprint results from a rape investigation. Suspect 1’s DNA matches that of the sperm found in the victim.

Uses of DNA fingerprinting In paternity and maternity tests – to check if a man or woman and a child are father/mother and son/daughter. In a landmark court case, Alec Jeffreys produced DNA profiles to prove to immigration officials that a girl was indeed the daughter of a mother living in the UK. To establish family relationships – for example, the remains of some bones found in Russia were shown to be those of the Russian royal family executed in 1917.