Embryo tests carry no extra health risk
Dr Jess Buxton
Progress Educational Trust
24 June 2007
Carrying out genetic tests on embryos has no effect on the health of the resulting babies, according to new findings reported at the annual meeting of the European Society of Human Genetics. The researchers, based at Brussels' Free University, followed up over 500 babies born following the use of preimplantation genetic diagnosis (PGD). They compared the children with those conceived using either standard IVF, or ICSI (intracytoplasmic sperm injection), during which a single sperm is injected directly into an egg.
PGD involves removing a single cell from a 3-5 day old embryo created using IVF or ICSI, to check for the presence of a gene mutation or chromosome abnormality responsible for a medical condition. Since all the cells that make up the embryo at this stage are 'totipotent' - able to develop into any body tissue - removing a single cell is believed to have no effect. Unaffected embryos, if any are identified, can then be transferred to the mother's womb to continue developing.
PGD has been used by couples who are at high risk of passing on serious genetic disorders to their children since the early 1990s. Since then, there have been calls to track children born after PGD to monitor their long-term health. In the latest study, the scientists studied 583 pregnancies, which resulted in 563 live births. Twenty were stillborn, and nine died shortly after birth. The team assessed the health of the children at the age of two months, and again at two years.
The researchers found that at 3.6 per cent, the rate of major birth defects in the PGD babies was no higher than that in the IVF or ICSI groups. However, team leader Professor Ingeborg Liebaers said that the perinatal death rate needed further investigation, as it was higher in the PGD group - particularly following multiple pregnancies. But overall she said the results were 'reassuring', adding 'it is good to know that a procedure that can offer patients hope of having a baby unaffected by serious disease is also safe in the longer term'.
Commenting on the findings, PGD pioneer and British Fertility spokesman Professor Alan Handyside said that he was 'very reassured and not at all surprised by these latest results'. However, he told BBC News Online that it would take several more decades to look at the longer term outcomes - the oldest PGD children are now 17. He said that the higher perinatal death rate was unexpected and should be investigated, as it could be a statistical anomaly.
© Copyright Progress Educational Trust
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.
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