New tests to identify unhealthy embryos

A new generation of genetic tests that would allow parents to select healthy babies is being considered for licensing by Britain's fertility watchdog.

A new generation of genetic tests that would allow parents to select healthy babies is being considered for licensing by Britain's fertility watchdog.

The tests, likely to be offered to parents having fertility treatment, would allow doctors to detect embryos with conditions such as Down's syndrome and discard them before they were implanted in the mother. The new form of genetic screening would also enable parents to discard embryos that werelikely to miscarry, thus improving the success rate of IVF treatment.

The fertility watchdog will also consider licensing the selection of embryos that have the potential to save dangerously ill siblings because they contain genetically compatible material. This follows the case of Molly Nash, an American girl whose life was endangered by a rare genetic form of anaemia. She was given a transplant using cells from the umbilical cord of her baby brother, Adam. Her brother's embryo was checked to see if he carried the gene responsible for his sister's condition.

Doctors believe licensing such genetic tests in Britain would help to reduce the risk of miscarriage because embryos with an abnormal number of chromosomes are more prone to abort. It would also enable them to screen for fatal illnesses such as Edward's syndrome, which leads to severe mental and physical disability in newborns and an early death for most children.

Such testing is likely to provoke accusations that doctors are trying to create "perfect babies" or playing God. It will raise fears that embryos lacking a perfect chromosonal make-up will be discarded. Pro-life groups have condemned such tests as a step towards creating so-called designer babies.

"This will lead to a designer baby culture. Once one has overstepped this mark and uses genetic manipulation for one reason its going to be difficult to stop it for other reasons," said Paul Tully, general secretary of the Society for the Protection of Unborn Children. "Testing for Down's syndrome usually means a fatal outcome. This sort of testing assumes that people with some genetic anomaly have less right to live."

The new form of aneuploid pre-implantation screening, which has never been licensed for use in Britain, would involve checking to see if embryos' DNA have abnormalities in chromosomes. "Aneuploid testing" involves removing a cell from the embryo and checking if the full number of chromosomes are present.

The technique would reduce the failure rate of treatment for infertile couples because it would allow doctors to screen out embryos with abnormalities that cause miscarriages. Pre-implantation genetic diagnosis is used at clinics in Britain to check for hereditary diseases such as cystic fibrosis, which can be detected from genetic abnormalities.

But doctors have been licensed to examine only five chromosomes for abnormalities, including cystic fibrosis and Huntington's disease.