The Wellcome Trust

DNA fingerprinting enters society

12/02/04 by GN

Part one of the DNA fingerprinting story examined its discovery. In part two, Sir Alec Jeffreys explains its first uses in immigration disputes and in criminology.

Immigration issues
When the first paper on DNA fingerprinting was published in spring 1985, it was covered in the press – and one report in the Guardian was read by Sheona York at the Hammersmith and Fulham Community Law Centre. Her clients, a Ghanaian family who were UK citizens living in London, were stuck in an immigration dispute. The youngest son had travelled back to Ghana, but on his return to the UK was detained due to an allegedly forged passport – the question being whether the boy coming back was in fact the son or was a substitute.

Standard DNA fingerprints in an immigration dispute


"We took the case on – and it was a tricky case," says Professor Jeffreys. "The woman had sisters back in Ghana, so the boy could have been a nephew, and we didn’t have the father for analysis. All we had were three fully accepted children – so we used these children to reconstruct the DNA fingerprint of the missing father. When you compared mum, dad, and the boy, the results were clear-cut – the boy was definitely the son."

The case against the son was dropped, and huge press coverage ensued. "It was a good news story of ‘science fighting bureaucracy and helping families’", says Professor Jeffreys. The University of Leicester switchboards were soon jammed with calls about immigration. "I didn’t realize the scale of the problem, thousands of families were trapped in exactly this sort of dispute," he adds. Indeed, DNA fingerprinting led to a change in the Immigration Act.

Innocent or guilty?
Although the principle of DNA fingerprinting seemed ideal for forensics, in practice the patterns would have been too complicated to explain in court. A slightly tweaked approach – termed DNA profiling – was the answer.

As Professor Jeffreys’s team uncovered more and more minisatellites in the human genome, they were finding some that were stupendously variable. DNA profiling therefore focused on just a few of these highly variable minisatellites, making the system more sensitive, more reproducible and amenable to computer databasing.

In 1986, the Enderby murder case, a case local to Leicester, saw the first use of DNA profiling in criminology. Two young girls had been raped and murdered, one in 1983 and one in 1986. After the second murder, a young man was arrested and gave a full confession. The police thought he must have committed the first murder as well, so they asked Professor Jeffreys to analyse forensic samples – semen from the first and second victims, samples from the victims, and blood from the prime suspect.

"The police were right – both girls had been raped by the same man," says ProfessorJeffreys. "But it wasn’t the man who had confessed. At first I thought there was something wrong with the technology, but we and the Home Office’s Forensic Science Service did additional testing and it was clear that it was not his semen. He had given a false confession and was released – so the first time DNA profiling was used in criminology, it was to prove innocence."

Armed with the DNA profile of the assailant, the police launched the world’s first DNA-based manhunt. Blood samples from more than 5000 men in the local community were collected. The murderer nearly got away with it – sending a proxy in to give a blood sample – but eventually he was apprehended and got two life sentences. "This man would have killed again, no doubt about it," says Professor Jeffreys. " DNA testing helped to save lives."

Within a year, DNA profiling was being used around the world. But the development of the technique was not finished. The arrival of the polymerase chain reaction enabled another huge leap in forensics: the development of national DNA databases.

In part three of the DNA fingerprinting story, Sir Alec Jeffreys discusses the introduction of PCR to DNA fingerprinting and the launch of the National DNA database, and argues for a DNA database for all citizens.

Further reading
Jeffreys A J, Wilson V and Thein S L (1985) Hypervariable 'minisatellite' regions in human DNA. Nature 314: 67-73.