Sir Alec John Jeffreys

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Sir Alec John Jeffreys


British Geneticist

Sir Alec John Jeffreys developed a ground-breaking new technique to identify different genetic patterns found in each individual person, except identical twins. He coined the term DNA fingerprinting, and his procedure revolutionized criminal investigations by enabling forensic scientists to identify suspects based on scant DNA evidence found in blood, tissue, and body fluids.

Jeffreys was born on January 9, 1950, in Oxford, England. When he was eight years old his father, Sidney Victor Jeffreys, a designer and engineer in the car industry, gave him a microscope and chemistry set. He became hooked on both biology and chemistry, and found the two subjects fit together in biochemistry. In 1975 Jeffreys received a Ph.D. in human genetics from the University of Oxford and went to Amsterdam to work on a project. While in Amsterdam, an interesting question occurred to him: If genes can be detected in DNA, can inherited differences among people be detected in their genes? When this was later found to be possible, a new area of molecular genetics research was opened up.

Finding how bits of human DNA are different came unexpectedly while working on another project concerning genes and the course of evolution. Jeffreys noted the same genetic sequences are repeated over and over, an occurrence he called "stuttered DNA." There are different numbers of stutters between people. These stutters or variable numbers of tandem repeats (VNTRs) he found could be cut with restriction enzymes and then separated into fragments by a process called polyacrylamide gel electrophoresis, or PAGE. The process uses agarose gel, a jelly-like material, in a device that creates an electrical field. The groups migrate according to size, creating a pattern that represents a distinct DNA fingerprint. The procedure is also called restriction fragment length polymorphism analysis (RFLP).

Jeffreys realized its potential for solving problems of identification. His first opportunity to use DNA fingerprinting occurred in March 1985, when he proved a boy was the son of a British citizen, allowing him to enter the country.

The first case of human DNA used in crime detection occurred the next year. A teenage girl was raped and strangled in a village near Jeffreys's laboratory in Leicester. Body fluids were recovered, but no suspect was found. Three years later it happened again. Another teenage girl was strangled in the same way as the first. A 19-year-old caterer confessed to the second murder but not to the first. However, the DNA evidence from both murders was the same. The man had falsely confessed to the murder of the second girl. The DNA evidence did eventually reveal the real killer when blood samples from 4582 village men were taken.

DNA evidence was first used in an American court to convict Tommy Lee Andrews of a Florida rape. The use of DNA evidence in criminal investigations soon spread worldwide.

In 1988 Kary Mullis (1944- ) discovered polymerase chain reaction (PCR), a technique that allows small amounts of DNA to be copied or amplified in test tubes. In 1990 Jeffreys used DNA analysis, with the help of PCR, to identify the skeletal remains of Joseph Mengele, the infamous Nazi doctor who performed barbaric experiments on Jewish prisoners at Auschwitz.

The technique developed by Jeffreys has been refined to identify small sequences called short tandem repeats (STRs). One of the most famous cases involving the use of DNA was the O.J. Simpson investigation in 1995. Jeffreys's work has provided an important tool for solving crimes.

Jeffreys teaches human genetics at the University of Leicester and has shifted his research focus to the study of DNA mutations from one generation to the next. He is especially interested in the effects of environment on DNA, including the genetic consequences of the Russian nuclear power plant accident in Chernobyl.

In 1994 Jeffreys was knighted by the Queen for his research in genetics and his contribution to the field of forensic DNA. He has received over 30 honors and prizes for his work.