Gene patents were an abhorrent concept to Professor Mike Stratton, head of the British team that discovered the second breast cancer gene BrCa2, until he realised it was the only way to retain some control of a sensitive clinical tool. The British patent was granted this month and applications are pending in the US and Europe. The patent has already been sub-licensed, but for the first time the licensing agreement includes a binding ethical code of conduct.

The story begins in 1991 when geneticists from Berkeley, California located a gene linked to familial breast cancer (BrCa1) on chromosome 17. This wasn't the only breast cancer gene as not all predisposed families had it. So, funded by the Cancer Research Campaign, Stratton and a team from the Institute of Cancer Research in London hunted for another gene. Believing their set of DNA samples would not be powerful enough to highlight a new gene, they agreed to share samples with European and US groups, including one from the University of Utah.

In 1994, Stratton then located a new gene, BrCa2, on chromosome 13 and was about to embark on the hard work of isolating it when the Utah University group isolated BrCa1 and decided to set up a company called Myriad Genetics to develop its commercial potential. "At this point we decided that we could not collaborate with Utah. One reason was that it is hard to look into the future and see what could happen if a company owned a gene as interesting as BrCa2. Also, we would be in collaboration with a commercial enterprise, but our main research base continued to be samples from patients, none of whom had been asked if we could give their sample to a commercial company."

So Stratton and co decided to go it alone and what was a collaboration became a competition. "We thought this was the end of our chances of being successful because Myriad Genetics was very experienced and heavily financed. But we did it and published in December 1995 with about three- quarters of the sequence. In March Myriad published, confirming our findings, and completing the remaining quarter of the sequence."

Then came the crux. To develop a useful diagnostic test for familial breast cancer, both genes would need to be involved. Myriad had already moved to take out a patent on BrCa1 and was proving an aggressive player.

"If we didn't take out a patent on BrCa2, they could have a monopoly on that too and have the power to prevent anyone else developing a test. We are wary of gene patents, but decided it was the only safe thing to do to retain any control of the use of our findings."

Defending a patent is expensive and Stratton's funders, the Cancer Research Campaign didn't feel they could use charitable money to this end. So this year the patent was sold to a US biotech company, Oncomed, in a contract festooned with protective provisos. Chief among them - any test developed with BrCa2 must only be made available to people referred by a clinician expert in the management of familial breast cancer and who gives full pre- and post-test counselling.

There must also be absolutely no lay advertising: "We don't want any drumming up of business to increase people's concern."

In addition, Oncomed must sub-license the patent to all other commercial organ- isations that want to develop a test or therapy, providing they agree to be bound by the ethical code. Finally, no not-for-profit organ-isation, including the NHS, can be charged for using BrCa2 in any way. "We did the work in the public sector, financed by charitable donations in state institutions. We did not want to find them paying again." There's little doubt Oncomed will profit from the licence, but so too will CRC. For the record, says Stratton, he has waived all personal royalties.

How effective this ethical approach is remains to be seen. But Stratton believes trying to return science to an unpatentable Garden of Eden is a non-starter. "In the Eighties when few genes had been patented, it might have been possible to stop it, and there would still have been the incentive to produce diag- nostics and therapeutics because genes are the primary resource of modern medicine. With some genes patented, companies are only going to work on those they can get the patent on because they believe they need that degree of security. If we stop now, new unpatented genes will simply be ignored.

"From here on in, any scientists working with anything remotely developable will have to consider the implications of patents."