Although the pregnancy failed, the scientists now have five more couples whose embryos are are expected to undergo cancer tests later this year. But the development of such tests for in vitro embryos raises fresh concerns about the creation of ''designer babies" that will only be born if they possess an approved genetic constitution.
Joy Delhanty, professor of human genetics at University College London, who carried out the test, acknowledged the breakthrough might be seen by some critics as paving the way for designer babies. ''Theoretically it could open the door," she said. "But for practical purposes it's never going to be easy to do it.''
The ethics of testing embryos for genetic defects before they are placed in the womb - called pre-implantation genetic diagnosis (PGD) - is being scrutinised by government- appointed experts and will be the subject of a public debate in London this week organised by the Wellcome Trust, Britain's largest research charity.
Up to 50 children in Britain have already been born after undergoing PGD as embryos but all were in families at risk of genetic disorders that usually strike in early life.
The cancer test was for an inherited predisposition to bowel cancer, which normally only kills adults. Opponents of genetic screening argue that this raises the prospect of screening out individuals who may have a perfectly healthy youth but who are destined to die prematurely. Prof Delhanty said the decision about whether to allow embryo screening for late-onset diseases should not be made by scientists or politicians. ''My view is that it's up to the family concerned."
The mother of the first embryo tested inherited a gene for polyposis, a type of familial bowel cancer, and frequently incurable. She had undergone radical surgery and had also lost her mother and two sisters to the disease.
Scientists cultured the woman's embryos for three days in a laboratory dish until they reach the eight-cell stage. They then extracted two cells from each embryo to see which ones were free of the polyposis defect.
They found one embryo that did not carry the defective gene and implanted it into the mother. Although the pregnancy failed, the scientists report in their research paper: ''We have shown that, technically, it is possible to detect mutations in cancer-predisposing genes at the single-cell level with confidence.''
They add, however, that "the ethical issues concerning embryo selection for diseases that are late-onset and are not immediately life-threatening remain controversial."
Prof Delhanty has five other couples who are expected to undergo the testing for a range of other inherited cancers. ''They have applied for funding and if they get it we will go ahead.''
Prof Christine Gosden, a geneticist at Liverpool University and a member of the Human Fertilisation and Embryology Authority's ethics committee investigating PGD, said PGD is not going to be the first step on the road to creating designer babies. "We're not talking about designer babies, we're talking about ways of preventing children being born with genetic disorders."
Sperm widow pregnant
DIANE BLOOD, the woman who won the right to take her late husband's sperm abroad for fertility treatment after a High Court legal battle last year, is pregnant. She said she was "absolutely delighted" at the news, which follows a controversial three-year campaign to have a child by her dead husband, Stephen, who died of meningitis in 1995. Mrs Blood's father, Mike Mahon, confirmed the pregnancy is in its "early stages" and is the result of fertility treatment. Full story, page 5Reuse content