This means that any future diagnostic test for breast cancer based on the gene research will be the property of a US biotechnology company - a prospect that worries some British researchers.
Less than 5 per cent of the 27,000 new cases of breast cancer in the UK each year are the result of inherited defects in the breast cancer gene, but the discovery is expected to help understand the other non-inherited cases.
Professor Mark Skolnick, of the University of Utah in Salt Lake City, won the race to find the breast cancer suseptibility gene - BRCA1 - ahead of about a dozen other scientific groups around the world, including at least two in Britain.
He has set up a company, Myriad Genetics, to develop a diagnostic test and to exploit the research commercially. A patent on the gene will protect the millions of dollars spent finding it and making a test, he said yesterday.
Professor Bruce Ponder, of Cambridge University, who was also trying to find the gene, said a number of researchers are concerned about Professor Skolnick's plans to patent the gene. 'Myriad Genetics could end up in a monopoly position. This could make the test more expensive than is necessary,' he said.
Professor Ponder said there are ethical concerns about a diagnostic test that is only relevant to some women and commercial pressures should not dictate when or how the test is introduced.
'We are uneasy about the principle of patenting genes. Finding a gene is just the final step in a pyramid of knowledge and the question is whether it is justifiable for one company to own the patent,' he said.
Professor Skolnick said it will take some time, perhaps a year, before a gene test is developed to help diagnose a breast cancer predisposition in women with a family history of the disease.
Myriad Genetics may charge a fee to scientists who use the patented research, he said. 'It's reasonable for some royalties to be paid.'
A second breast cancer gene was announced yesterday by scientists from the Institute of Cancer Research, in London. Like BRCA1, the second gene increases the risk of breast cancer in some women with a family history of the disease. It may take many years, however, before BRCA2 is finally isolated.