ALEC JEFFREYS

Alec Jeffreys was born in January 1950 in Oxford, United Kingdom. Jeffreys is clearly a man with science in his genes: “I think I was born to be a scientist, as I was already fascinated by the subject at the age of five.” His path was further determined some three years later, when his father gave him a microscope and a large chemistry set.

His interest in experimental chemistry and biology continued to grow and he went on to study biochemistry at Merton College, Oxford, then undertook his PhD on the mitochondria of cultured mammalian cells at the Genetics Laboratory, also at Oxford. Thereafter he moved to the University of Amsterdam, where he worked as a research fellow on mammalian genes. In 1977 Jeffreys moved back to the UK to lecture in the Department of Genetics at the University of Leicester, where he invented DNA fingerprinting in 1984.

Today Jeffreys is Professor of Genetics at the University of Leicester and continues to work at the genetics laboratory. When not working, he enjoys surfboarding (not often in Leicester) and philately. He is a Distinguished Supporter of the British Humanist Association and likes to boast that he is one of the top Twister players on staff at Leicester University!

“I have to confess that I simply haven’t grown up. I think deep inside I’m still stuck at age 14 with my chemistry set; it’s just curiosity that keeps me going! The ability to keep experimenting and discovering things about the universe in which we live is a great privilege – as well as a fantastic hobby. So that’s why I love what I do.”

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DNA fingerprinting in wikipedia
How to create a DNA fingerprint?
DNA evidence in HowStuffWorks

Innovation

The “Eureka” moment

The birth of the DNA fingerprinting can be pinpointed exactly to the morning of September 10th, 1984. It was then that Jeffreys had a “eureka” moment" in his Leicester lab while examining an X-ray that formed part of a DNA experiment regarding genetic markers for inheritance patterns of illness.

But what the experiment showed, unexpectedly, were the similarities and differences in his technician's family's DNA. Jeffreys quickly realized the import of this discovery of a biological identification mechanism. “That moment changed my life,” he says. And it led to the development of techniques that would fundamentally change this important area of science.

How to make a DNA fingerprint?

The first step is to extract DNA from the cells in a sample of blood, saliva, semen or other appropriate fluid or tissue. The traditional way to fingerprint DNA is by doing what is called a Southern blot. The DNA being analyzed must be separated from other material, cut into a few different-sized pieces using restriction enzymes, which are proteins that can cut double-stranded DNA without damaging the bases. Different length minisatellite alleles give differently-sized DNA fragments and can therefore be sized and compared by measuring the lengths of these fragments.

After this the DNA fragments are transferred from the fragile gel to a strong sheet of nylon or nitrocellulose paper membrane. The gel is discarded and the DNA is ready to be analyzed using a radioactive probe in a hybridization reaction by DNA polymerase.

A piece of X-ray film is exposed to the membrane after radioactive probing and fragments that have bound to the probe appear as black bands when the X-ray film is developed.

By measuring how far the fragments have moved through the gel one can calculate their sizes and therefore obtain the lengths of the different alleles. If one is checking family relationships, for example, one can see if a child has alleles the same size as one of those of either parent.

DNA fingerprinting evolves

The original method of DNA fingerprinting was slow and required large quantities of quality DNA, while the new methods use smaller amounts of DNA and samples that may also be more degraded than those previously used.

DNA fingerprinting took a huge leap forward with the invention of the polymerase chain reaction. Both discriminating power and ability to recover information from very small initial samples was now possible by amplification of specific regions of DNA using a cycling of temperature and a thermostable polymerase enzyme along with fluorescently-labelled sequence-specific primers of DNA.

Recent innovations have included the creation of primers targeting polymorphic regions on the Y-chromosome, which allows resolution of multiple male profiles, or for cases in which a differential extraction is not possible. Y-chromosomes are paternally-inherited, so analysis can help in the identification of paternally-related males.

Applications

DNA fingerprinting was first put to use when Jeffreys was asked to help in a disputed immigration case to confirm the identity of a British boy whose family was originally from Ghana. The boy had gone back to Ghana and returned to the UK with a suspicious-looking passport and authorities suspected that it might not in fact be the same child that originally left. It was a tough case but Jeffreys was eventually able to prove, using this new science of his, that the boy was who he claimed to be.

DNA fingerprinting was first used as a police forensic test in 1986 in an apparent copycat rape and murder case. Jeffreys was brought in by the UK police to assist in identifying the culprit.

It has played a key role in many high publicity cases. In one early achievement it was used to confirm the identity for German prosecutors of the Nazi Dr. Josef Mengele, who had died in 1979, by comparing DNA obtained from a femur bone of his exhumed skeleton and DNA from his widow and son, in a similar way to paternity testing.

In another controversial case, DNA analysis was performed to determine if Thomas Jefferson had sired a son with one of his slaves. And mitochondrial DNA testing was used in determining that Anna Anderson was not the Russian princess Anastasia Romanov she had claimed to be.

The most recent ethnogeographic research uses DNA profiles to trace origins of population groups looking at geographic variations in human genome. And the method can also be applied to non-human species, for example in wildlife population genetics studies.

Before the DNA fingerprinting was commercialized in 1987 the laboratory of Prof Jeffreys was the only centre in the world conducting DNA fingerprinting. Now, however, DNA fingerprints are examined everywhere, even in portable laboratories, and the equipment for genetic fingerprinting is being made by dozens of companies around the world.

DNA fingerprinting has a vital role to play on contemporary society; genetic research continues, making DNA-related applications more common in many areas of life. This has raised also some ethical questions, particularly regarding the potential for genetic information to be used to limit freedoms and invade privacy.