British geneticist Sir Alec Jeffreys developed the DNA fingerprinting technique (DNA fingerprinting) in 1984.This technique is a method of identifying individuals using DNA repeat sequences that differ from one individual to another. Jefferies’ findings are based on the fact that the short repeat sequences (so-called mini satellite sequences) in individual DNA have different patterns for each individual.
1. How DNA fingerprinting works
The technology developed by Jefferies focuses on repetitive sequences (repeated portions of short DNA sequences) in non-coding regions (regions that do not directly contain genetic information).Since the number and arrangement of these repetitive sequences differ from person to person, comparison of these repetitive sequences enables individual identification.
Specific Processes
- DNA sample extraction: DNA is extracted from blood, hair, skin, etc.
- Restriction Enzyme Cleavage: DNA is cleaved using restriction enzymes that recognize specific DNA sequences.
- Electrophoresis: The cut DNA fragments are subjected to gel electrophoresis and separated by size.
- Southern blotting: DNA fragments are transferred to a membrane and a radioactive probe is used to detect specific repeat sequences.
- Pattern comparison: The pattern of DNA fragments thus obtained differs from individual to individual like a barcode, and this pattern is called the DNA fingerprint. By comparing these patterns, we can identify individuals and parent-child relationships.
2. Application
Jefferies’ technology has revolutionized many areas.
1. Forensics
DNA fingerprinting plays a pivotal role in criminal investigations. In 1986, Jefferies’ technology attracted considerable attention when it became the first in the world to successfully identify a murderer by DNA fingerprinting.
2. Paternity test
DNA fingerprinting is also used to confirm parent-child relationships. By comparing DNA patterns passed down from parent to child, parent-child relationships can be confirmed with a high degree of accuracy.
3. Immigration Application
In the late 1980s, DNA fingerprinting was also used in immigration applications in the United Kingdom. The technique was used as conclusive evidence in cases where proof of kinship was at issue.
4. Biodiversity Research
DNA fingerprinting has also been applied to the study of genetic diversity in animals and plants. Genetic differences within the same species are examined and used in conservation and breeding programs.
3. Comparison with modern technology
The DNA fingerprinting technique developed by Jefferies became the basis for subsequent simpler and more accurate DNA identification techniques such as STR (Short Tandem Repeat) analysis. Today, STR analysis is commonly used to quickly and reliably identify individuals by examining shorter repeat sequences (STRs) instead of mini satellite sequences.
Summary
The DNA fingerprinting technology developed by Alec Jeffries has revolutionized personal identification, paternity testing, and criminal investigation by exploiting the differences in DNA sequences between individuals. This technology has become an indispensable foundation in modern forensic science and genetics, contributing significantly to scientific progress.
Supervisor of the article
Dr. Hiroshi Oka
Graduated from Keio University, Faculty of Medicine
Doctor of Medicine
Medical Doctor
