Gene structure: It's life, Jim

It is a dramatic step into a brave new world. Longer than 50 years after Watson and Crick's breathtakingly important study on gene structure, a man is to become the first to receive a fully-decoded copy of his own DNA blueprint.

Appropriately perhaps, the man will be Nobel prize winner Jim Watson, now 79, who will go down in history, with Francis Crick, as one of the most famous double acts in science.

Project Jim, as it is known, will mark the start of a new era in human genetics when we are all able to order the full details of our genetic sequences as encoded in the two copies of DNA we received from our parents.

Until now, full gene sequencing has been the stuff of science fiction, as envisaged in the film Gattaca, starring Ethan Hawke and Uma Thurman. The film depicts a future driven by eugenics, when babies are genetically engineered and life expectations identified from their DNA at birth. A biometric database divides people into "valids "(the genetically engineered) and (natural-born) "in-valids".

In reality, Project Jim could herald a new era in medicine when doctors are able to scan our genomes for signs of genetic alterations that could predispose us to certain illnesses, such as heart disorder, and Alzheimer's disease.

An American company which has pioneered an ultra-fast way of sequencing the individual "letters" of the DNA alphabet has sequenced the correct order of the 3 billion letters of Watson's DNA - and repeated the effort six times to ensure there are no mistakes.

The company has done this for both copies of Watson's DNA - he inherited one from his mother and one from his father - because this would have to be done to search for mutations that could lead to illness. This made the decoding effort twice as onerous, with 6 billion DNA "base pairs" being fully sequenced in their correct order.

This week, the biotech firm 454 Life Sciences of Branford, Connecticut, is scheduled to finish the task. And at a ceremony at Baylor University in Houston, Texas, it will present Watson with his full DNA sequence in a digital format burned on to a single DVD.

"We are almost there. Because it's all been done through random sampling, it means you've got to do it many times to get it right," said Richard Gibbs, a DNA sequencer at Baylor College of Medicine, who took a lead role in the project.

"We're doing the quality assurance on his genome to make sure we have it right," Dr Gibbs said.

It took longer than 10 years and $4 bn (£2.2bn) to sequence the three billion letters of the human genome, which was a composite made from dozens of different individuals. This time, it took less than two years to sequence six billion base pairs of Watson's DNA at a cost of $2m.

The cost of sequencing DNA and the amount of time it takes have fallen dramatically and it will soon be possible to do it for the public. "This tells us it's getting there in terms of cost," Dr Gibbs said.

Some sceptics have suggested that Watson will in fact be the second person to have their genome sequenced because the first sequence belonged to Dr Craig Venter, the American scientist involved in the private effort to decode the human genome and who is said to have provided his own DNA for the effort.

But there are questions about just how much of Venter's DNA made up the full sequence decoded by the private effort he led.

"Venter certainly didn't provide all the data for the genome. We are really not sure how much of his DNA was used. We believe that Watson will be the first," Dr Gibbs said.

Meanwhile, though Dr Watson is happy to share his DNA on the public database, there are some things he does not want to know about himself. He does not want to know whether he is likely to get a debilitating condition for which there is no cure.

It is the sort of ethical issue that we may all soon have to face once the day of the cheap and cheerful genome sequence arrives .