Screening embryos for 'problem' c...( Pre-implantation genetic diagnosis ...)

Pre-implantation genetic diagnosis of embryos is beginning to live up to the early expectations of fertility experts, bringing new hope to couples who had despaired of ever being parents or having a baby unaffected by a genetic abnormality, the European Society of Human Reproduction and Embryology annual conference heard today, Wednesday 28 June.

It was already being shown to cut dramatically the number of miscarriages in older mothers who had used the procedure and to reduce the number of babies born with an inherited chromosomal condition that results in severe handicap.

Dr Santiago Munn from the Saint Barnabas Medical Centre in New Jersey, USA, said that pre-implantation genetic diagnosis (PGD) for aneuploidy (a condition in which the cells of an embryo have the wrong number of chromosomes) and for translocations (where part or whole chromosomes move to a different position or become attached to another chromosome), is now available in most developed countries. However, large-scale PGD for those conditions was still confined to a total of only half a dozen centres in the Netherlands, USA, Italy, Belgium and the UK.

The risk of aneuploidy rises up to 70-fold as women get older. Many embryos don't implant and of those that do the result can be an early miscarriage or handicaps such as Down's Syndrome.

Around 9% of couples where the woman suffers repeated miscarriages involve translocations and any babies born are severely handicapped.

Women at high risk can be offered IVF. Doctors use molecular probes around day three of embryo development to recognise these conditions and ensure that only healthy embryos are transferred to the uterus.

"Of 65 translocation diagnoses we have carried out, the spontaneous abortion rate was only 15%, compared with 95% of the pregnancies conceived without screening," Dr Munn said.

"One in a hundred women over 35 may have aneuploidy and this rises to four in a hundred for wom
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Contact: Margaret Willson
m.willson@mwcommunications.org.uk
44-1536-772181
European Society for Human Reproduction and Embryology
27-Jun-2000