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OAS Supplement, Science & Technology

DNA Fingerprinting

A Sample DNA

DNA fingerprinting is a method used to identify an individual from a sample of DNA by looking at unique patterns in their DNA. DNA fingerprinting is a technique of detecting specific sequences of deoxyribonucleic acid (DNA) for a unique individual. It uses the polymerase chain reaction to amplify the specific sequences of DNA and to make its clones. It is used to establish lineages and also for identifying criminals.

DNA fingerprinting was invented in 1984 by Professor Sir Alec Jeffreys after he realised you could detect variations in human DNA, in the form of these minisatellites. In this technique, DNA is isolated from a tiny segment of any type of tissues—semen, hair, blood or skin. It is washed and cut into fragments by restricting enzymes that cleave the DNA molecule at specific locations. The fragments are then sorted by size. Some segments are repeated at regular intervals. The repeated segments are then tagged with radioactive probes that allow the fragments to be visualized as patterns of bands on photographic paper. The resultant image will have regular patterns of bands. The image is then matched with DNA collected from the suspect.

DNA is the genetic material carried neatly packed in the chromosomes within the nucleus of the each cell. It is known that certain regions on DNA are made up of tandem repeats of short sequences, known as mini-satellites. It is found that variation in the pattern of repetitive sequences of mini-satellites is very high, which makes the possible number of permutations so large that it is highly unlikely that the same combination could be repeated in the DNA of another person.


Since it was invented in 1984, DNA fingerprinting most often has been used in court cases and legal matters. It can:
1. Physically connect a piece of evidence to a person or rule out someone as a suspect.
2. Show who your parents, siblings, and other relatives may be.
3. Identify a dead body that’s too old or damaged to be recognizable.

DNA fingerprinting is extremely accurate. Most countries now keep DNA records on file in much the same way police keep copies of actual fingerprints. It also has medical uses. It can:
1. Match tissues of organ donors with those of people who need transplants.
2. Identify diseases that are passed down through your family.
3. Help find cures for those diseases, called hereditary conditions.

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